Document:

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                                DOUBLETWIST, INC.

                                 2000 STOCK PLAN

          1. PURPOSES OF THE PLAN. The purposes of this 2000 Stock Plan are:

             -    to attract and retain the best available personnel for
                  positions of substantial responsibility,

             -    to provide additional incentive to Employees, Directors and
                  Consultants, and

             -    to promote the success of the Company's business.

             Options granted under the Plan may be Incentive Stock Options or
Nonstatutory Stock Options, as determined by the Administrator at the time of
grant. Stock Purchase Rights may also be granted under the Plan.

          2. DEFINITIONS. As used herein, the following definitions shall apply:

               (a) "ADMINISTRATOR" means the Board or any of its Committees as
shall be administering the Plan, in accordance with Section 4 of the Plan.

               (b) "APPLICABLE LAWS" means the requirements relating to the
administration of stock option plans under U. S. state corporate laws, U.S.
federal and state securities laws, the Code, any stock exchange or quotation
system on which the Common Stock is listed or quoted and the applicable laws of
any foreign country or jurisdiction where Options or Stock Purchase Rights are,
or will be, granted under the Plan.

               (c) "BOARD" means the Board of Directors of the Company.

               (d) "CHANGE OF CONTROL" means the occurrence of any of the
          following events:

                    (i)   Any "person" (as such term is used in Sections 13(d)
and 14(d) of the Exchange Act) becomes the "beneficial owner" (as defined in
Rule 13d-3 of the Exchange Act), directly or indirectly, of securities of the
Company representing fifty percent (50%) or more of the total voting power
represented by the Company's then outstanding voting securities; or

                    (ii)  The consummation of the sale or disposition by the
Company of all or substantially all of the Company's assets; or

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                    (iii) The consummation of a merger or consolidation of the
Company with any other corporation, other than a merger or consolidation which
would result in the voting securities of the Company outstanding immediately
prior thereto continuing to represent (either by remaining outstanding or by
being converted into voting securities of the surviving entity or its parent) at
least fifty percent (50%) of the total voting power represented by the voting
securities of the Company or such surviving entity or its parent outstanding
immediately after such merger or consolidation.

                    (iv)  A change in the composition of the Board, as a result
of which fewer than a majority of the Directors are Incumbent Directors.
"Incumbent Directors" shall mean Directors who either (A) are Directors of the
Company as of the date hereof, or (B) are elected, or nominated for election, to
the Board with the affirmative votes of at least a majority of those Directors
whose election or nomination was not in connection with any transaction
described in subsections (i), (ii) or (iii) or in connection with an actual or
threatened proxy contest relating to the election of directors of the Company.

               (e) "CODE" means the Internal Revenue Code of 1986, as amended.

               (f) "COMMITTEE" means a committee of Directors appointed by the
Board in accordance with Section 4 of the Plan.

               (g) "COMMON STOCK" means the common stock of the Company.

               (h) "COMPANY" means DoubleTwist, Inc., a California corporation.

               (i) "CONSULTANT" means any person, including an advisor, engaged
by the Company or a Parent or Subsidiary to render services to such entity.

               (j) "DIRECTOR" means a member of the Board.

               (k) "DISABILITY" means total and permanent disability as defined
in Section 22(e)(3) of the Code.

               (l) "EMPLOYEE" means any person, including Officers and
Directors, employed by the Company or any Parent or Subsidiary of the Company. A
Service Provider shall not cease to be an Employee in the case of (i) any leave
of absence approved by the Company or (ii) transfers between locations of the
Company or between the Company, its Parent, any Subsidiary, or any successor.
For purposes of Incentive Stock Options, no such leave may exceed ninety days,
unless reemployment upon expiration of such leave is guaranteed by statute or
contract. If reemployment upon expiration of a leave of absence approved by the
Company is not so guaranteed, on the 181st day of such leave any Incentive Stock
Option held by the Optionee shall cease to be treated as an Incentive Stock
Option and shall be treated for tax purposes as a Nonstatutory Stock Option.
Neither service as a Director nor payment of a director's fee by the Company
shall be sufficient to constitute "employment" by the Company.

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               (m) "EXCHANGE ACT" means the Securities Exchange Act of 1934, as
amended.

               (n) "FAIR MARKET VALUE" means, as of any date, the value of
Common Stock determined as follows:

                    (i)   If the Common Stock is listed on any established stock
exchange or a national market system, including without limitation the Nasdaq
National Market or The Nasdaq SmallCap Market of The Nasdaq Stock Market, its
Fair Market Value shall be the closing sales price for such stock (or the
closing bid, if no sales were reported) as quoted on such exchange or system for
the last market trading day prior to the time of determination, as reported in
THE WALL STREET JOURNAL or such other source as the Administrator deems
reliable;

                    (ii)  If the Common Stock is regularly quoted by a
recognized securities dealer but selling prices are not reported, the Fair
Market Value of a Share of Common Stock shall be the mean between the high bid
and low asked prices for the Common Stock on the last market trading day prior
to the day of determination, as reported in THE WALL STREET JOURNAL or such
other source as the Administrator deems reliable; or

                    (iii) In the absence of an established market for the Common
Stock, the Fair Market Value shall be determined in good faith by the
Administrator.

               (o) "INCENTIVE STOCK OPTION" means an Option intended to qualify
as an incentive stock option within the meaning of Section 422 of the Code and
the regulations promulgated thereunder.

               (p) "INSIDE DIRECTOR" means a Director who is an Employee.

               (q) "IPO EFFECTIVE DATE" means the date upon which the Securities
and Exchange Commission declares the initial public offering of the Company's
Common Stock as effective.

               (r) "NONSTATUTORY STOCK OPTION" means an Option not intended to
qualify as an Incentive Stock Option.

               (s) "NOTICE OF GRANT" means a written or electronic notice
evidencing certain times and conditions of an individual Option or Stock
Purchase Right grant. The Notice of Grant is part of the Option Agreement.

               (t) "OFFICER" means a person who is an officer of the Company
within the meaning of Section 16 of the Exchange Act and the rules and
regulations promulgated thereunder.

               (u) "OPTION" means a stock option granted pursuant to the Plan.

               (v) "OPTION AGREEMENT" means an agreement between the Company and
an Optionee evidencing the terms and conditions of an individual Option grant.
The Option Agreement is subject to the terms and conditions of the Plan.

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               (w) "OPTION EXCHANGE PROGRAM" means a program whereby outstanding
Options are surrendered in exchange for Options with a lower exercise price.

               (x) "OPTIONED STOCK" means the Common Stock subject to an Option
or Stock Purchase Right.

               (y) "OPTIONEE" means the holder of an outstanding Option or Stock
Purchase Right granted under the Plan.

               (z) "OUTSIDE DIRECTOR" means a Director who is not an Employee.

               (aa) "PLAN" means this 2000 Stock Option Plan, as amended and
restated.

               (bb) "RESTRICTED STOCK" means shares of Common Stock acquired
pursuant to a grant of Stock Purchase Rights under Section 11 of the Plan.

               (cc) "RESTRICTED STOCK PURCHASE AGREEMENT" means a written
agreement between the Company and the Optionee evidencing the terms and
restrictions applying to stock purchased under a Stock Purchase Right. The
Restricted Stock Purchase Agreement is subject to the terms and conditions of
the Plan and the Notice of Grant.

               (dd) "RULE 16b-3" means Rule 16b-3 of the Exchange Act or any
successor to Rule 16b-3, as in effect when discretion is being exercised with
respect to the Plan.

               (ee) "SECTION 16(b) " means Section 16(b) of the Exchange Act.

               (ff) "SERVICE PROVIDER" means an Employee, Director or
Consultant.

               (gg) "SHARE" means a share of the Common Stock, as adjusted in
accordance with Section 14 of the Plan.

               (hh) "STOCK PURCHASE RIGHT" means the right to purchase Common
Stock pursuant to Section 11 of the Plan, as evidenced by a Notice of Grant.

               (ii) "SUBSIDIARY" means a "subsidiary corporation", whether now
or hereafter existing, as defined in Section 424(f) of the Code.

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          3. STOCK SUBJECT TO THE PLAN. Subject to the provisions of Section 14
of the Plan, the maximum aggregate number of Shares which may be optioned and
sold under the Plan is 1,000,000 Shares, plus any Shares available for future
issuance under the Pangea Systems, Inc. 1996 Equity Incentive Plan (the "1996
Plan") on the date the Securities and Exchange Commission declares the company's
registration statement effective and any Shares returned to the 1996 Stock Plan.

          The number of Shares reserved for issuance under the Plan shall
increase annually on the first day of the Company's fiscal year beginning in
2001 by an amount of Shares equal to the lesser of (i) 1,500,000 Shares, (ii) 5%
of the outstanding Shares on such date or (iii) an amount determined by the
Board. The Shares may be authorized, but unissued, or reacquired Common Stock.

               If an Option or Stock Purchase Right expires or becomes
unexercisable without having been exercised in full, or is surrendered pursuant
to an Option Exchange Program, the unpurchased Shares which were subject thereto
shall become available for future grant or sale under the Plan (unless the Plan
has terminated); provided, however, that Shares that have actually been issued
under the Plan, whether upon exercise of an Option or Right, shall not be
returned to the Plan and shall not become available for future distribution
under the Plan, except that if Shares of Restricted Stock are repurchased by the
Company at their original purchase price, such Shares shall become available for
future grant under the Plan.

          4. ADMINISTRATION OF THE PLAN.

               (a) PROCEDURE.

                    (i)   MULTIPLE ADMINISTRATIVE BODIES. The Plan may be
administered by different Committees with respect to different groups of Service
Providers.

                    (ii)  SECTION 162(m). To the extent that the Administrator
determines it to be desirable to qualify Options granted hereunder as
"performance-based compensation" within the meaning of Section 162(m) of the
Code, the Plan shall be administered by a Committee of two or more "outside
directors" within the meaning of Section 162(m) of the Code.

                    (iii) RULE 16b-3. To the extent desirable to qualify
transactions hereunder as exempt under Rule 16b-3, the transactions contemplated
hereunder shall be structured to satisfy the requirements for exemption under
Rule 16b-3.

                    (iv) OTHER ADMINISTRATION. Other than as provided above, the
Plan shall be administered by (A) the Board or (B) a Committee, which committee
shall be constituted to satisfy Applicable Laws.

               (b) POWERS OF THE ADMINISTRATOR. Subject to the provisions of the
Plan, and in the case of a Committee, subject to the specific duties delegated
by the Board to such Committee, the Administrator shall have the authority, in
its discretion:

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                    (i)    to determine the Fair Market Value;

                    (ii)   to select the Service Providers to whom Options and
Stock Purchase Rights may be granted hereunder;

                    (iii)  to determine the number of shares of Common Stock to
be covered by each Option and Stock Purchase Right granted hereunder;

                    (iv)   to approve forms of agreement for use under the Plan;

                    (v)    to determine the terms and conditions, not
inconsistent with the terms of the Plan, of any Option or Stock Purchase Right
granted hereunder. Such terms and conditions include, but are not limited to,
the exercise price, the time or times when Options or Stock Purchase Rights may
be exercised (which may be based on performance criteria), any vesting
acceleration or waiver of forfeiture restrictions, and any restriction or
limitation regarding any Option or Stock Purchase Right or the shares of Common
Stock relating thereto, based in each case on such factors as the Administrator,
in its sole discretion, shall determine;

                    (vi)   to reduce the exercise price of any Option or Stock
Purchase Right to the then current Fair Market Value if the Fair Market Value of
the Common Stock covered by such Option or Stock Purchase Right shall have
declined since the date the Option or Stock Purchase Right was granted;

                    (vii)  to institute an Option Exchange Program;

                    (viii) to construe and interpret the terms of the Plan and
awards granted pursuant to the Plan;

                    (ix)   to prescribe, amend and rescind rules and regulations
relating to the Plan, including rules and regulations relating to sub-plans
established for the purpose of qualifying for preferred tax treatment under
foreign tax laws;

                    (x)    to modify or amend each Option or Stock Purchase
Right (subject to Section 16(c) of the Plan), including the discretionary
authority to extend the post-termination exercisability period of Options longer
than is otherwise provided for in the Plan;

                    (xi)   to allow Optionees to satisfy withholding tax
obligations by electing to have the Company withhold from the Shares to be
issued upon exercise of an Option or Stock Purchase Right that number of Shares
having a Fair Market Value equal to the amount required to be withheld. The Fair
Market Value of the Shares to be withheld shall be determined on the date that
the amount of tax to be withheld is to be determined. All elections by an
Optionee to have Shares withheld for this purpose shall be made in such form and
under such conditions as the Administrator may deem necessary or advisable;

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                    (xii)  to authorize any person to execute on behalf of the
Company any instrument required to effect the grant of an Option or Stock
Purchase Right previously granted by the Administrator;

                    (xiii) to make all other determinations deemed necessary or
advisable for administering the Plan.

               (c) EFFECT OF ADMINISTRATOR'S DECISION. The Administrator's
decisions, determinations and interpretations shall be final and binding on all
Optionees and any other holders of Options or Stock Purchase Rights.

          5. ELIGIBILITY. Nonstatutory Stock Options and Stock Purchase Rights
may be granted to Service Providers. Incentive Stock Options may be granted only
to Employees.

          6. LIMITATIONS.

               (a) Each Option shall be designated in the Option Agreement as
either an Incentive Stock Option or a Nonstatutory Stock Option. However,
notwithstanding such designation, to the extent that the aggregate Fair Market
Value of the Shares with respect to which Incentive Stock Options are
exercisable for the first time by the Optionee during any calendar year (under
all plans of the Company and any Parent or Subsidiary) exceeds $100,000, such
Options shall be treated as Nonstatutory Stock Options. For purposes of this
Section 6(a), Incentive Stock Options shall be taken into account in the order
in which they were granted. The Fair Market Value of the Shares shall be
determined as of the time the Option with respect to such Shares is granted.

               (b) Neither the Plan nor any Option or Stock Purchase Right shall
confer upon an Optionee any right with respect to continuing the Optionee's
relationship as a Service Provider with the Company, nor shall they interfere in
any way with the Optionee's right or the Company's right to terminate such
relationship at any time, with or without Cause.

               (c) The following limitations shall apply to grants of Options:

                    (i)   No Service Provider shall be granted, in any fiscal
year of the Company, Options to purchase more than 1,500,000 Shares.

                    (ii)  In connection with his or her initial service, a
Service Provider may be granted Options to purchase up to an additional
3,000,000 Shares, which shall not count against the limit, set forth in
subsection (i) above.

                    (iii) The foregoing limitations shall be adjusted
proportionately in connection with any change in the Company's capitalization as
described in Section 14.

                    (iv)  If an Option is cancelled in the same fiscal year of
the Company in which it was granted (other than in connection with a transaction
described in Section 14), the cancelled Option will be counted against the
limits set forth in subsections (i) and (ii) above. For

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this purpose, if the exercise price of an Option is reduced, the transaction
will be treated as a cancellation of the Option and the grant of a new Option.

          7. TERM OF PLAN. Subject to Section 20 of the Plan, the Plan shall
become effective upon its adoption by the Board. It shall continue in effect for
a term of ten (10) years unless terminated earlier under Section 16 of the Plan.

          8. TERM OF OPTION. The term of each Option shall be stated in the
Option Agreement. In the case of an Incentive Stock Option, the term shall be
ten (10) years from the date of grant or such shorter term as may be provided in
the Option Agreement. Moreover, in the case of an Incentive Stock Option granted
to an Optionee who, at the time the Incentive Stock Option is granted, owns
stock representing more than ten percent (10%) of the total combined voting
power of all classes of stock of the Company or any Parent or Subsidiary, the
term of the Incentive Stock Option shall be five (5) years from the date of
grant or such shorter term as may be provided in the Option Agreement.

          9. OPTION EXERCISE PRICE AND CONSIDERATION.

               (a) EXERCISE PRICE. The per share exercise price for the Shares
to be issued pursuant to exercise of an Option shall be determined by the
Administrator, subject to the following:

                    (i)   In the case of an Incentive Stock Option

                          (A) granted to an Employee who, at the time the
Incentive Stock Option is granted, owns stock representing more than ten percent
(10%) of the voting power of all classes of stock of the Company or any Parent
or Subsidiary, the per Share exercise price shall be no less than 110% of the
Fair Market Value per Share on the date of grant.

                          (B) granted to any Employee other than an Employee
described in paragraph (A) immediately above, the per Share exercise price shall
be no less than 100% of the Fair Market Value per Share on the date of grant.

                    (ii)  In the case of a Nonstatutory Stock Option, the per
Share exercise price shall be determined by the Administrator. In the case of a
Nonstatutory Stock Option intended to qualify as "performance-based
compensation" within the meaning of Section 162(m) of the Code, the per Share
exercise price shall be no less than 100% of the Fair Market Value per Share on
the date of grant.

                    (iii) Notwithstanding the foregoing, Options may be granted
with a per Share exercise price of less than 100% of the Fair Market Value per
Share on the date of grant pursuant to a merger or other corporate transaction.

               (b) Waiting Period and Exercise Dates. At the time an Option is
granted, the Administrator shall fix the period within which the Option may be
exercised and shall determine any conditions that must be satisfied before the
Option may be exercised.

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               (c) FORM OF CONSIDERATION. The Administrator shall determine the
acceptable form of consideration for exercising an Option, including the method
of payment. In the case of an Incentive Stock Option, the Administrator shall
determine the acceptable form of consideration at the time of grant. Such
consideration may consist entirely of:

                    (i)    cash;

                    (ii)   check;

                    (iii)  promissory note;

                    (iv)   other Shares which (A) in the case of Shares acquired
upon exercise of an option, have been owned by the Optionee for more than six
months on the date of surrender, and (B) have a Fair Market Value on the date of
surrender equal to the aggregate exercise price of the Shares as to which said
Option shall be exercised;

                    (v)    consideration received by the Company under a
cashless exercise program implemented by the Company in connection with the
Plan;

                    (vi)   a reduction in the amount of any Company liability to
the Optionee, including any liability attributable to the Optionee's
participation in any Company-sponsored deferred compensation program or
arrangement;

                    (vii)  any combination of the foregoing methods of payment;
or

                    (viii) such other consideration and method of payment for
the issuance of Shares to the extent permitted by Applicable Laws.

          10. EXERCISE OF OPTION.

               (a) PROCEDURE FOR EXERCISE; RIGHTS AS A SHAREHOLDER. Any Option
granted hereunder shall be exercisable according to the terms of the Plan and at
such times and under such conditions as determined by the Administrator and set
forth in the Option Agreement. Unless the Administrator provides otherwise,
vesting of Options granted hereunder shall be tolled during any unpaid leave of
absence. An Option may not be exercised for a fraction of a Share.

                    An Option shall be deemed exercised when the Company
receives: (i) written or electronic notice of exercise (in accordance with the
Option Agreement) from the person entitled to exercise the Option, and (ii) full
payment for the Shares with respect to which the Option is exercised. Full
payment may consist of any consideration and method of payment authorized by the
Administrator and permitted by the Option Agreement and the Plan. Shares issued
upon exercise of an Option shall be issued in the name of the Optionee or, if
requested by the Optionee, in the name of the Optionee and his or her spouse.
Until the Shares are issued (as evidenced by the appropriate entry on the books
of the Company or of a duly authorized transfer agent of the Company), no right
to vote or receive dividends or any other rights as a shareholder shall exist
with respect to the

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Optioned Stock, notwithstanding the exercise of the Option. The Company shall
issue (or cause to be issued) such Shares promptly after the Option is
exercised. No adjustment will be made for a dividend or other right for which
the record date is prior to the date the Shares are issued, except as provided
in Section 14 of the Plan.

                    Exercising an Option in any manner shall decrease the number
of Shares thereafter available, both for purposes of the Plan and for sale under
the Option, by the number of Shares as to which the Option is exercised.

               (b) TERMINATION OF RELATIONSHIP AS A SERVICE PROVIDER. Subject to
Section 14, if an Optionee ceases to be a Service Provider (but not in the event
of an Optionee's change of status from Employee to Consultant (in which case an
Employee's Incentive Stock Option shall automatically convert to a Nonstatutory
Stock Option on the ninety-first (91st) day following such change of status) or
from Consultant to Employee), such Optionee may, but only within such period of
time as is specified in the Option Agreement (but in no event later than the
expiration date of the term of such Option as set forth in the Option
Agreement), exercise his or her Option to the extent that Optionee was entitled
to exercise it at the date of such termination. In the absence of a specified
time in the Option Agreement, the Option shall remain exercisable for three (3)
months following the Optionee's termination. If, on the date of termination, the
Optionee is not vested as to his or her entire Option, the Shares covered by the
unvested portion of the Option shall revert to the Plan. If, after termination,
the Optionee does not exercise his or her Option within the time specified by
the Administrator, the Option shall terminate, and the Shares covered by such
Option shall revert to the Plan.

               (c) DISABILITY OF OPTIONEE. If an Optionee ceases to be a Service
Provider as a result of the Optionee's Disability, the Optionee may, but only
within twelve (12) months from the date of such termination (and in no event
later than the expiration date of the term of such Option as set forth in the
Option Agreement), exercise his or her Option to the extent that the Option is
vested on the date of termination. If, on the date of termination, the Optionee
is not vested as to his or her entire Option, the Shares covered by the unvested
portion of the Option shall revert to the Plan. If, after termination, the
Optionee does not exercise his or her Option within the time specified herein,
the Option shall terminate, and the Shares covered by such Option shall revert
to the Plan.

               (d) DEATH OF OPTIONEE. If an Optionee dies while a Service
Provider, the Option may be exercised at any time within twelve (12) months
following the date of death (but in no event later than the expiration of the
term of such Option as set forth in the Notice of Grant), by the Optionee's
estate or by a person who acquires the right to exercise the Option by bequest
or inheritance, but only to the extent that the Option is vested on the date of
death. If, at the time of death, the Optionee is not vested as to his or her
entire Option, the Shares covered by the unvested portion of the Option shall
immediately revert to the Plan. The Option may be exercised by the executor or
administrator of the Optionee's estate or, if none, by the person(s) entitled to
exercise the Option under the Optionee's will or the laws of descent or
distribution. If the Option is not so exercised within the time specified
herein, the Option shall terminate, and the Shares covered by such Option shall
revert to the Plan.

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               (e) BUYOUT PROVISIONS. The Administrator may at any time offer to
buy out for a payment in cash or Shares an Option previously granted based on
such terms and conditions as the Administrator shall establish and communicate
to the Optionee at the time that such offer is made.

          11. STOCK PURCHASE RIGHTS.

               (a) RIGHTS TO PURCHASE. Stock Purchase Rights may be issued
either alone, in addition to, or in tandem with other awards granted under the
Plan and/or cash awards made outside of the Plan. After the Administrator
determines that it will offer Stock Purchase Rights under the Plan, it shall
advise the offeree in writing or electronically, by means of a Notice of Grant,
of the terms, conditions and restrictions related to the offer, including the
number of Shares that the offeree shall be entitled to purchase, the price to be
paid, and the time within which the offeree must accept such offer. The offer
shall be accepted by execution of a Restricted Stock Purchase Agreement in the
form determined by the Administrator.

               (b) REPURCHASE OPTION. Unless the Administrator determines
otherwise, the Restricted Stock Purchase Agreement shall grant the Company a
repurchase option exercisable upon the voluntary or involuntary termination of
the purchaser's service with the Company for any reason (including death or
Disability). The purchase price for Shares repurchased pursuant to the
Restricted Stock Purchase Agreement shall be the original price paid by the
purchaser and may be paid by cancellation of any indebtedness of the purchaser
to the Company. The repurchase option shall lapse at a rate determined by the
Administrator.

               (c) OTHER PROVISIONS. The Restricted Stock Purchase Agreement
shall contain such other terms, provisions and conditions not inconsistent with
the Plan as may be determined by the Administrator in its sole discretion.

               (d) RIGHTS AS A SHAREHOLDER. Once the Stock Purchase Right is
exercised, the purchaser shall have the rights equivalent to those of a
shareholder, and shall be a shareholder when his or her purchase is entered upon
the records of the duly authorized transfer agent of the Company. No adjustment
will be made for a dividend or other right for which the record date is prior to
the date the Stock Purchase Right is exercised, except as provided in Section 14
of the Plan.

          12. NON-TRANSFERABILITY OF OPTIONS AND STOCK PURCHASE RIGHTS. Unless
determined otherwise by the Administrator, an Option or Stock Purchase Right may
not be sold, pledged, assigned, hypothecated, transferred, or disposed of in any
manner other than by will or by the laws of descent or distribution and may be
exercised, during the lifetime of the Optionee, only by the Optionee. If the
Administrator makes an Option or Stock Purchase Right transferable, such Option
or Stock Purchase Right shall contain such additional terms and conditions as
the Administrator deems appropriate.

          13. FORMULA OPTION GRANTS TO OUTSIDE DIRECTORS. Outside Directors
shall be granted Options in accordance with the following provisions:

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               (a) All Options granted pursuant to this Section shall be
Nonstatutory Stock Options and, except as otherwise provided herein, shall be
subject to the other terms and conditions of the Plan.

               (b) Except as provided in subsection (d) below, each person who
is an Outside Director on the IPO Effective Date or who first becomes an Outside
Director after the IPO Effective Date, whether through election by the
stockholders of the Company or appointment by the Board to fill a vacancy shall
be automatically granted an Option to purchase up to 15,000 Shares (the "First
Option") on the later of the date he or she first becomes an Outside Director or
the IPO Effective Date; provided, however, that an Inside Director who ceases to
be an Inside Director but who remains a Director shall not receive a First
Option.

               (c) Except as provided in subsection (d) below, each Outside
Director shall be automatically granted an Option to purchase up to 5,000 Shares
(a "Subsequent Option") following each annual meeting of the stockholders of the
Company occurring after the end of the Company's fiscal year 2000, if
immediately after such meeting, he or she shall continue to serve on the Board
and shall have served on the Board for at least the preceding six (6) months.

               (d) Notwithstanding the provisions of subsections (b) and (c)
hereof, any exercise of an Option granted before the Company has obtained
stockholder approval of the Plan in accordance with Section 20 hereof shall be
conditioned upon obtaining such stockholder approval of the Plan in accordance
with Section 20 hereof.

               (e) The terms of each First Option granted pursuant to this
Section shall be as follows:

                    (i)   the term of the Option shall be ten (10) years.

                    (ii)  the exercise price per Share shall be 100% of the Fair
Market Value per Share on the date of grant of the Option.

                    (iii) the Shares subject to the First Option shall vest on
the effective date of the Company's initial public offering.

               (f) the terms of each Subsequent Option granted pursuant to this
Section shall be as follows:

                    (i)   the term of the Option shall be ten (10) years.

                    (ii)  the exercise price per Share shall be 100% of the Fair
Market Value per Share on the date of grant of the Option.

                    (iii) the Shares subject to each Subsequent Option shall
vest twelve months after the date of grant provided that the Outside Director
shall continue to serve on the Board on such date.

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          14. ADJUSTMENTS UPON CHANGES IN CAPITALIZATION, MERGER OR ASSET SALE.

               (a) CHANGES IN CAPITALIZATION. Subject to any required action by
the stockholders of the Company, the number of shares of Common Stock covered by
each outstanding Option or Stock Purchase Right, and the number of shares of
Common Stock which have been authorized for issuance under the Plan but as to
which no Options or Stock Purchase Rights have yet been granted or which have
been returned to the Plan upon cancellation or expiration of an Option or Stock
Purchase Right, as well as the price per share of Common Stock covered by each
such outstanding Option or Stock Purchase Right, shall be proportionately
adjusted for any increase or decrease in the number of issued shares of Common
Stock resulting from a stock split, reverse stock split, stock dividend,
combination or reclassification of the Common Stock, or any other increase or
decrease in the number of issued shares of Common Stock effected without receipt
of consideration by the Company. The conversion of any convertible securities of
the Company shall not be deemed to have been "effected without receipt of
consideration." Such adjustment shall be made by the Board, whose determination
in that respect shall be final, binding and conclusive. Except as expressly
provided herein, no issuance by the Company of shares of stock of any class, or
securities convertible into shares of stock of any class, shall affect, and no
adjustment by reason thereof shall be made with respect to, the number or price
of shares of Common Stock subject to an Option or Stock Purchase Right.

               (b) DISSOLUTION OR LIQUIDATION. In the event of the proposed
dissolution or liquidation of the Company, the Administrator shall notify each
Optionee as soon as practicable prior to the effective date of such proposed
transaction. The Administrator in its discretion may provide for an Optionee to
have the right to exercise his or her Option or Stock Purchase Right until
fifteen (15) days prior to such transaction as to all of the Optioned Stock
covered thereby, including Shares as to which the Option or Stock Purchase Right
would not otherwise be exercisable. In addition, the Administrator may provide
that any Company repurchase option applicable to any Shares purchased upon
exercise of an Option or Stock Purchase Right shall lapse as to all such Shares,
provided the proposed dissolution or liquidation takes place at the time and in
the manner contemplated. To the extent it has not been previously exercised, an
Option or Stock Purchase Right will terminate immediately prior to the
consummation of such proposed action.

               (c) MERGER OR ASSET SALE. Subject to Section 15 below, in the
event of a merger of the Company with or into another corporation, or the sale
of substantially all of the assets of the Company (a "Merger"), each outstanding
Option and Stock Purchase Right shall be assumed or an equivalent option or
right substituted by the successor corporation or a Parent or Subsidiary of the
successor corporation (the "Successor Corporation"). In the event that the
Successor Corporation refuses to assume or substitute for the Option or Stock
Purchase Right, the Optionee shall fully vest in and have the right to exercise
the Option or Stock Purchase Right as to all of the Optioned Stock, including
Shares as to which it would not otherwise be vested or exercisable. If an Option
or Stock Purchase Right becomes fully vested and exercisable in lieu of
assumption or substitution in the event of a Merger, the Administrator shall
notify the Optionee in writing or electronically that the Option or Stock
Purchase Right shall be fully vested and exercisable for a period of fifteen
(15) days from the date of such notice, and the Option or Stock Purchase Right
shall terminate upon the

                                      -13-

<PAGE>

expiration of such period. For the purposes of this Section 14(c), the Option or
Stock Purchase Right shall be considered assumed if, following the Merger, the
option or right confers the right to purchase or receive, for each Share of
Optioned Stock subject to the Option or Stock Purchase Right immediately prior
to the Merger, the consideration (whether stock, cash, or other securities or
property) received in the Merger by holders of Common Stock for each Share held
on the effective date of the transaction (and if holders were offered a choice
of consideration, the type of consideration chosen by the holders of a majority
of the outstanding Shares); provided, however, that if such consideration
received in the Merger is not solely common stock of the Successor Corporation
or its Parent, the Administrator may, with the consent of the Successor
Corporation, provide for the consideration to be received upon the exercise of
the Option or Stock Purchase Right, for each Share of Optioned Stock subject to
the Option or Stock Purchase Right, to be solely common stock of the Successor
Corporation or its Parent equal in fair market value to the per share
consideration received by holders of Common Stock in the Merger.

          15. CHANGE OF CONTROL. In the event of a Change of Control, each
outstanding Option held by an Outside Director shall vest and become exercisable
in full as to all of the Optioned Stock, including Shares as to which the
Outside Director would not otherwise be vested or exercisable. If an Option
becomes fully vested and exercisable as provided in this paragraph, the
Administrator shall notify the Optionee in writing or electronically that the
Option shall be fully vested and exercisable for a period of fifteen (15) days
from the date of such notice, and the Option shall terminate upon the expiration
of such period.

          16. DATE OF GRANT. The date of grant of an Option or Stock Purchase
Right shall be, for all purposes, the date on which the Administrator makes the
determination granting such Option or Stock Purchase Right, or such other later
date as is determined by the Administrator. Notice of the determination shall be
provided to each Optionee within a reasonable time after the date of such grant.

          17. AMENDMENT AND TERMINATION OF THE PLAN.

               (a) AMENDMENT AND TERMINATION. The Board may at any time amend,
alter, suspend or terminate the Plan.

               (b) SHAREHOLDER APPROVAL. The Company shall obtain shareholder
approval of any Plan amendment to the extent necessary and desirable to comply
with Applicable Laws.

               (c) EFFECT OF AMENDMENT OR TERMINATION. No amendment, alteration,
suspension or termination of the Plan shall impair the rights of any Optionee,
unless mutually agreed otherwise between the Optionee and the Administrator,
which agreement must be in writing and signed by the Optionee and the Company.
Termination of the Plan shall not affect the Administrator's ability to exercise
the powers granted to it hereunder with respect to Options granted under the
Plan prior to the date of such termination.

                                      -14-

<PAGE>

          18. CONDITIONS UPON ISSUANCE OF SHARES.

               (a) LEGAL COMPLIANCE. Shares shall not be issued pursuant to the
exercise of an Option or Stock Purchase Right unless the exercise of such Option
or Stock Purchase Right and the issuance and delivery of such Shares shall
comply with Applicable Laws and shall be further subject to the approval of
counsel for the Company with respect to such compliance.

               (b) INVESTMENT REPRESENTATIONS. As a condition to the exercise of
an Option or Stock Purchase Right, the Company may require the person exercising
such Option or Stock Purchase Right to represent and warrant at the time of any
such exercise that the Shares are being purchased only for investment and
without any present intention to sell or distribute such Shares if, in the
opinion of counsel for the Company, such a representation is required.

          19. INABILITY TO OBTAIN AUTHORITY. The inability of the Company to
obtain authority from any regulatory body having jurisdiction, which authority
is deemed by the Company's counsel to be necessary to the lawful issuance and
sale of any Shares hereunder, shall relieve the Company of any liability in
respect of the failure to issue or sell such Shares as to which such requisite
authority shall not have been obtained.

          20. RESERVATION OF SHARES. The Company, during the term of this Plan,
will at all times reserve and keep available such number of Shares as shall be
sufficient to satisfy the requirements of the Plan.

          21. SHAREHOLDER APPROVAL. The Plan shall be subject to approval by the
shareholders of the Company within twelve (12) months after the date the Plan is
adopted. Such shareholder approval shall be obtained in the manner and to the
degree required under Applicable Laws.

                                      -15-<PAGE>

                               DOUBLETWIST, INC.

                        2000 EMPLOYEE STOCK PURCHASE PLAN

         The following constitute the provisions of the 2000 Employee Stock
Purchase Plan of DoubleTwist, Inc.

         1.       PURPOSE. The purpose of the Plan is to provide employees of
the Company and its Designated Subsidiaries with an opportunity to purchase
Common Stock of the Company through accumulated payroll deductions. It is the
intention of the Company to have the Plan qualify as an "Employee Stock Purchase
Plan" under Section 423 of the Internal Revenue Code of 1986, as amended. The
provisions of the Plan, accordingly, shall be construed so as to extend and
limit participation in a manner consistent with the requirements of that section
of the Code.

         2.       DEFINITIONS.

                  (a)      "BOARD" shall mean the Board of Directors of the
Company or any committee thereof designated by the Board of Directors of the
Company in accordance with Section 14 of the Plan.

                  (b)      "CODE" shall mean the Internal Revenue Code of 1986,
as amended.

                  (c)      "COMMON STOCK" shall mean the common stock of the
Company.

                  (d)      "COMPANY" shall mean DoubleTwist, Inc. and any
Designated Subsidiary of the Company.

                  (e)      "COMPENSATION" shall mean all base straight time
gross earnings, commissions, but exclusive of payments for overtime, shift
premium, incentive compensation, bonuses and other compensation.

                  (f)      "DESIGNATED SUBSIDIARY" shall mean any Subsidiary
that has been designated by the Board from time to time in its sole discretion
as eligible to participate in the Plan.

                  (g)      "EMPLOYEE" shall mean any individual who is an
Employee of the Company for tax purposes whose customary employment with the
Company is at least twenty (20) hours per week and more than five (5) months in
any calendar year. For purposes of the Plan, the employment relationship shall
be treated as continuing intact while the individual is on sick leave or other
leave of absence approved by the Company. Where the period of leave exceeds 90
days and the individual's right to reemployment is not guaranteed either by
statute or by contract, the employment relationship shall be deemed to have
terminated on the 91st day of such leave.

                  (h)      "ENROLLMENT DATE" shall mean the first Trading Day of
each Offering Period.

                  (i)      "EXERCISE DATE" shall mean the last Trading Day of
each Purchase Period.

<PAGE>

                  (j)      "FAIR MARKET VALUE" shall mean, as of any date, the
value of Common Stock determined as follows:

                           (i)      If the Common Stock is listed on any
established stock exchange or a national market system, including without
limitation the Nasdaq National Market or The Nasdaq SmallCap Market of The
Nasdaq Stock Market, its Fair Market Value shall be the closing sales price for
such stock (or the closing bid, if no sales were reported) as quoted on such
exchange or system for the last market trading day prior to the date of
determination, as reported in THE WALL STREET JOURNAL or such other source as
the Board deems reliable;

                           (ii)     If the Common Stock is regularly quoted by a
recognized securities dealer but selling prices are not reported, its Fair
Market Value shall be the mean of the closing bid and asked prices for the
Common Stock prior to the date of determination, as reported in THE WALL STREET
JOURNAL or such other source as the Board deems reliable;

                           (iii)    In the absence of an established market for
the Common Stock, the Fair Market Value thereof shall be determined in good
faith by the Board; or

                           (iv)     For purposes of the Enrollment Date of the
first Offering Period under the Plan, the Fair Market Value shall be the initial
price to the public as set forth in the final prospectus included within the
registration statement in Form S-1 filed with the Securities and Exchange
Commission for the initial public offering of the Company's Common Stock (the
"Registration Statement").

                  (k)      "OFFERING PERIODS" shall mean the periods of
approximately twenty-four (24) months during which an option granted pursuant to
the Plan may be exercised, commencing on the first Trading Day on or after
January 1 and July 1 of each year and terminating on the last Trading Day in the
periods ending twenty-four months later; provided, however, that the first
Offering Period under the Plan shall commence with the first Trading Day on or
after the date on which the Securities and Exchange Commission declares the
Company's Registration Statement effective and ending on the last Trading Day on
or before June 30, 2002. The duration and timing of Offering Periods may be
changed pursuant to Section 4 of this Plan.

                  (l)      "PLAN" shall mean this 2000 Employee Stock Purchase
Plan.

                  (m)      "PURCHASE PERIOD" shall mean the approximately six
month period commencing after one Exercise Date and ending with the next
Exercise Date, except that the first Purchase Period of any Offering Period
shall commence on the Enrollment Date and end with the next Exercise Date.

                  (n)      "PURCHASE PRICE" shall mean 85% of the Fair Market
Value of a share of Common Stock on the Enrollment Date or on the Exercise Date,
whichever is lower; provided however, that the Purchase Price may be adjusted by
the Board pursuant to Section 20.

                  (o)      "RESERVES" shall mean the number of shares of Common
Stock covered by each option under the Plan which have not yet been exercised
and the number of shares of Common Stock which have been authorized for issuance
under the Plan but not yet placed under option.

                                      -2-
<PAGE>

                  (p)      "SUBSIDIARY" shall mean a corporation, domestic or
foreign, of which not less than 50% of the voting shares are held by the Company
or a Subsidiary, whether or not such corporation now exists or is hereafter
organized or acquired by the Company or a Subsidiary.

                  (q)      "TRADING DAY" shall mean a day on which national
stock exchanges and the Nasdaq System are open for trading.

         3.       ELIGIBILITY.

                  (a)      Any Employee who shall be employed by the Company on
a given Enrollment Date shall be eligible to participate in the Plan.

                  (b)      Any provisions of the Plan to the contrary
notwithstanding, no Employee shall be granted an option under the Plan (i) to
the extent that, immediately after the grant, such Employee (or any other person
whose stock would be attributed to such Employee pursuant to Section 424(d) of
the Code) would own capital stock of the Company and/or hold outstanding options
to purchase such stock possessing five percent (5%) or more of the total
combined voting power or value of all classes of the capital stock of the
Company or of any Subsidiary, or (ii) to the extent that his or her rights to
purchase stock under all employee stock purchase plans of the Company and its
subsidiaries accrues at a rate which exceeds Twenty-Five Thousand Dollars
($25,000) worth of stock (determined at the fair market value of the shares at
the time such option is granted) for each calendar year in which such option is
outstanding at any time.

         4.       OFFERING PERIODS. The Plan shall be implemented by
consecutive, overlapping Offering Periods with a new Offering Period commencing
on the first Trading Day on or after January 1 and July 1 each year, or on such
other date as the Board shall determine, and continuing thereafter until
terminated in accordance with Section 20 hereof; provided, however, that the
first Offering Period under the Plan shall commence with the first Trading Day
on or after the date on which the Securities and Exchange Commission declares
the Company's Registration Statement effective and ending on the last Trading
Day on or before June 30, 2002. The Board shall have the power to change the
duration of Offering Periods (including the commencement dates thereof) with
respect to future offerings without shareholder approval if such change is
announced at least five (5) days prior to the scheduled beginning of the first
Offering Period to be affected thereafter.

         5.       PARTICIPATION.

                  (a)      An eligible Employee may become a participant in the
Plan by completing a subscription agreement authorizing payroll deductions in
the form of Exhibit A to this Plan and filing it with the Company's payroll
office prior to the applicable Enrollment Date.

                  (b)      Payroll deductions for a participant shall commence
on the first payroll following the Enrollment Date and shall end on the last
payroll in the Offering Period to which such authorization is applicable, unless
sooner terminated by the participant as provided in Section 10 hereof.

                                      -3-
<PAGE>

         6.       PAYROLL DEDUCTIONS.

                  (a)      At the time a participant files his or her
subscription agreement, he or she shall elect to have payroll deductions made on
each pay day during the Offering Period in an amount not exceeding fifteen
percent (15%) of the Compensation which he or she receives on each pay day
during the Offering Period.

                  (b)      All payroll deductions made for a participant shall
be credited to his or her account under the Plan and shall be withheld in whole
percentages only. A participant may not make any additional payments into such
account.

                  (c)      A participant may discontinue his or her
participation in the Plan as provided in Section 10 hereof, or may increase or
decrease the rate of his or her payroll deductions during the Offering Period by
completing or filing with the Company a new subscription agreement authorizing a
change in payroll deduction rate. The Board may, in its discretion, limit the
number of participation rate changes during any Offering Period. The change in
rate shall be effective with the first full payroll period following five (5)
business days after the Company's receipt of the new subscription agreement
unless the Company elects to process a given change in participation more
quickly. A participant's subscription agreement shall remain in effect for
successive Offering Periods unless terminated as provided in Section 10 hereof.

                  (d)      Notwithstanding the foregoing, to the extent
necessary to comply with Section 423(b)(8) of the Code and Section 3(b) hereof,
a participant's payroll deductions may be decreased to zero percent (0%) at any
time during a Purchase Period. Payroll deductions shall recommence at the rate
provided in such participant's subscription agreement at the beginning of the
first Purchase Period which is scheduled to end in the following calendar year,
unless terminated by the participant as provided in Section 10 hereof.

                  (e)      At the time the option is exercised, in whole or in
part, or at the time some or all of the Company's Common Stock issued under the
Plan is disposed of, the participant must make adequate provision for the
Company's federal, state, or other tax withholding obligations, if any, which
arise upon the exercise of the option or the disposition of the Common Stock. At
any time, the Company may, but shall not be obligated to, withhold from the
participant's compensation the amount necessary for the Company to meet
applicable withholding obligations, including any withholding required to make
available to the Company any tax deductions or benefits attributable to sale or
early disposition of Common Stock by the Employee.

         7.       GRANT OF OPTION. On the Enrollment Date of each Offering
Period, each eligible Employee participating in such Offering Period shall be
granted an option to purchase on each Exercise Date during such Offering Period
(at the applicable Purchase Price) up to a number of shares of the Company's
Common Stock determined by dividing such Employee's payroll deductions
accumulated prior to such Exercise Date and retained in the Participant's
account as of the Exercise Date by the applicable Purchase Price; provided that
in no event shall an Employee be permitted to purchase during each Purchase
Period more than 10,000 shares of the Company's Common Stock (subject to any
adjustment pursuant to Section 19), and provided further that such purchase
shall be subject to the limitations set forth in Sections 3(b) and 12 hereof.
The Board may, for future Offering Periods, increase or decrease, in its
absolute discretion, the maximum number of shares of

                                      -4-
<PAGE>

the Company's Common Stock an Employee may purchase during each Purchase Period
of such Offering Period. Exercise of the option shall occur as provided in
Section 8 hereof, unless the participant has withdrawn pursuant to Section 10
hereof. The option shall expire on the last day of the Offering Period.

         8.       EXERCISE OF OPTION.

                  (a)      Unless a participant withdraws from the Plan as
provided in Section 10 hereof, his or her option for the purchase of shares
shall be exercised automatically on the Exercise Date, and the maximum number of
full shares subject to option shall be purchased for such participant at the
applicable Purchase Price with the accumulated payroll deductions in his or her
account. No fractional shares shall be purchased; any payroll deductions
accumulated in a participant's account which are not sufficient to purchase a
full share shall be retained in the participant's account for the subsequent
Purchase Period or Offering Period, subject to earlier withdrawal by the
participant as provided in Section 10 hereof. Any other monies left over in a
participant's account after the Exercise Date shall be returned to the
participant. During a participant's lifetime, a participant's option to purchase
shares hereunder is exercisable only by him or her.

                  (b)      If the Board determines that, on a given Exercise
Date, the number of shares with respect to which options are to be exercised may
exceed (i) the number of shares of Common Stock that were available for sale
under the Plan on the Enrollment Date of the applicable Offering Period, or (ii)
the number of shares available for sale under the Plan on such Exercise Date,
the Board may in its sole discretion (x) provide that the Company shall make a
pro rata allocation of the shares of Common Stock available for purchase on such
Enrollment Date or Exercise Date, as applicable, in as uniform a manner as shall
be practicable and as it shall determine in its sole discretion to be equitable
among all participants exercising options to purchase Common Stock on such
Exercise Date, and continue all Offering Periods then in effect, or (y) provide
that the Company shall make a pro rata allocation of the shares available for
purchase on such Enrollment Date or Exercise Date, as applicable, in as uniform
a manner as shall be practicable and as it shall determine in its sole
discretion to be equitable among all participants exercising options to purchase
Common Stock on such Exercise Date, and terminate any or all Offering Periods
then in effect pursuant to Section 20 hereof. The Company may make pro rata
allocation of the shares available on the Enrollment Date of any applicable
Offering Period pursuant to the preceding sentence, notwithstanding any
authorization of additional shares for issuance under the Plan by the Company's
shareholders subsequent to such Enrollment Date.

         9.       DELIVERY. As promptly as practicable after each Exercise Date
on which a purchase of shares occurs, the Company shall arrange the delivery to
each participant, as appropriate, of a certificate representing the shares
purchased upon exercise of his or her option.

         10.      WITHDRAWAL.

                  (a)      A participant may withdraw all but not less than all
the payroll deductions credited to his or her account and not yet used to
exercise his or her option under the Plan at any time by giving written notice
to the Company in the form of Exhibit B to this Plan. All of the participant's
payroll deductions credited to his or her account shall be paid to such
participant

                                      -5-
<PAGE>

promptly after receipt of notice of withdrawal and such participant's option for
the Offering Period shall be automatically terminated, and no further payroll
deductions for the purchase of shares shall be made for such Offering Period. If
a participant withdraws from an Offering Period, payroll deductions shall not
resume at the beginning of the succeeding Offering Period unless the participant
delivers to the Company a new subscription agreement.

                  (b)      A participant's withdrawal from an Offering Period
shall not have any effect upon his or her eligibility to participate in any
similar plan which may hereafter be adopted by the Company or in succeeding
Offering Periods which commence after the termination of the Offering Period
from which the participant withdraws.

         11.      TERMINATION OF EMPLOYMENT.

                  Upon a participant's ceasing to be an Employee, for any
reason, he or she shall be deemed to have elected to withdraw from the Plan and
the payroll deductions credited to such participant's account during the
Offering Period but not yet used to exercise the option shall be returned to
such participant or, in the case of his or her death, to the person or persons
entitled thereto under Section 15 hereof, and such participant's option shall be
automatically terminated. The preceding sentence notwithstanding, a participant
who receives payment in lieu of notice of termination of employment shall be
treated as continuing to be an Employee for the participant's customary number
of hours per week of employment during the period in which the participant is
subject to such payment in lieu of notice.

         12.      INTEREST. No interest shall accrue on the payroll deductions
of a participant in the Plan.

         13.      STOCK.

                  (a)      Subject to adjustment upon changes in capitalization
of the Company as provided in Section 19 hereof, the maximum number of shares of
the Company's Common Stock which shall be made available for sale under the Plan
shall be 400,000 shares plus an annual increase to be added on the first day of
the Company's fiscal year beginning in 2001, equal to the lesser of (i) 300,000
shares, (ii) 3% of the outstanding shares on such date or (iii) a lesser amount
determined by the Board.

                  (b)      The participant shall have no interest or voting
right in shares covered by his option until such option has been exercised.

                  (c)      Shares to be delivered to a participant under the
Plan shall be registered in the name of the participant or in the name of the
participant and his or her spouse.

         14.      ADMINISTRATION. The Plan shall be administered by the Board or
a committee of members of the Board appointed by the Board. The Board or its
committee shall have full and exclusive discretionary authority to construe,
interpret and apply the terms of the Plan, to determine eligibility and to
adjudicate all disputed claims filed under the Plan. Every finding, decision and
determination made by the Board or its committee shall, to the full extent
permitted by law, be final and binding upon all parties.

                                      -6-
<PAGE>

         15.      DESIGNATION OF BENEFICIARY.

                  (a)      A participant may file a written designation of a
beneficiary who is to receive any shares and cash, if any, from the
participant's account under the Plan in the event of such participant's death
subsequent to an Exercise Date on which the option is exercised but prior to
delivery to such participant of such shares and cash. In addition, a participant
may file a written designation of a beneficiary who is to receive any cash from
the participant's account under the Plan in the event of such participant's
death prior to exercise of the option. If a participant is married and the
designated beneficiary is not the spouse, spousal consent shall be required for
such designation to be effective.

                  (b)      Such designation of beneficiary may be changed by the
participant at any time by written notice. In the event of the death of a
participant and in the absence of a beneficiary validly designated under the
Plan who is living at the time of such participant's death, the Company shall
deliver such shares and/or cash to the executor or administrator of the estate
of the participant, or if no such executor or administrator has been appointed
(to the knowledge of the Company), the Company, in its discretion, may deliver
such shares and/or cash to the spouse or to any one or more dependents or
relatives of the participant, or if no spouse, dependent or relative is known to
the Company, then to such other person as the Company may designate.

         16.      TRANSFERABILITY. Neither payroll deductions credited to a
participant's account nor any rights with regard to the exercise of an option or
to receive shares under the Plan may be assigned, transferred, pledged or
otherwise disposed of in any way (other than by will, the laws of descent and
distribution or as provided in Section 15 hereof) by the participant. Any such
attempt at assignment, transfer, pledge or other disposition shall be without
effect, except that the Company may treat such act as an election to withdraw
funds from an Offering Period in accordance with Section 10 hereof.

         17.      USE OF FUNDS. All payroll deductions received or held by the
Company under the Plan may be used by the Company for any corporate purpose, and
the Company shall not be obligated to segregate such payroll deductions.

         18.      REPORTS. Individual accounts shall be maintained for each
participant in the Plan. Statements of account shall be given to participating
Employees at least annually, which statements shall set forth the amounts of
payroll deductions, the Purchase Price, the number of shares purchased and the
remaining cash balance, if any.

         19.      ADJUSTMENTS UPON CHANGES IN CAPITALIZATION, DISSOLUTION,
LIQUIDATION, MERGER OR ASSET SALE.

                  (a)      CHANGES IN CAPITALIZATION. Subject to any required
action by the shareholders of the Company, the Reserves, the maximum number of
shares each participant may purchase each Purchase Period (pursuant to Section
7), as well as the price per share and the number of shares of Common Stock
covered by each option under the Plan which has not yet been exercised shall be
proportionately adjusted for any increase or decrease in the number of issued
shares of Common Stock resulting from a stock split, reverse stock split, stock
dividend, combination or reclassification of the Common Stock, or any other
increase or decrease in the number of shares of Common Stock effected without
receipt of consideration by the Company; provided, however, that conversion of

                                      -7-
<PAGE>

any convertible securities of the Company shall not be deemed to have been
"effected without receipt of consideration." Such adjustment shall be made by
the Board, whose determination in that respect shall be final, binding and
conclusive. Except as expressly provided herein, no issuance by the Company of
shares of stock of any class, or securities convertible into shares of stock of
any class, shall affect, and no adjustment by reason thereof shall be made with
respect to, the number or price of shares of Common Stock subject to an option.

                  (b)      DISSOLUTION OR LIQUIDATION. In the event of the
proposed dissolution or liquidation of the Company, the Offering Period then in
progress shall be shortened by setting a new Exercise Date (the "New Exercise
Date"), and shall terminate immediately prior to the consummation of such
proposed dissolution or liquidation, unless provided otherwise by the Board. The
New Exercise Date shall be before the date of the Company's proposed dissolution
or liquidation. The Board shall notify each participant in writing, at least ten
(10) business days prior to the New Exercise Date, that the Exercise Date for
the participant's option has been changed to the New Exercise Date and that the
participant's option shall be exercised automatically on the New Exercise Date,
unless prior to such date the participant has withdrawn from the Offering Period
as provided in Section 10 hereof.

                  (c)      MERGER OR ASSET SALE. In the event of a proposed sale
of all or substantially all of the assets of the Company, or the merger of the
Company with or into another corporation, each outstanding option shall be
assumed or an equivalent option substituted by the successor corporation or a
Parent or Subsidiary of the successor corporation. In the event that the
successor corporation refuses to assume or substitute for the option, any
Purchase Periods then in progress shall be shortened by setting a new Exercise
Date (the "New Exercise Date") and any Offering Periods then in progress shall
end on the New Exercise Date. The New Exercise Date shall be before the date of
the Company's proposed sale or merger. The Board shall notify each participant
in writing, at least ten (10) business days prior to the New Exercise Date, that
the Exercise Date for the participant's option has been changed to the New
Exercise Date and that the participant's option shall be exercised automatically
on the New Exercise Date, unless prior to such date the participant has
withdrawn from the Offering Period as provided in Section 10 hereof.

         20.      AMENDMENT OR TERMINATION.

                  (a)      The Board of Directors of the Company may at any time
and for any reason terminate or amend the Plan. Except as provided in Section 19
hereof, no such termination can affect options previously granted, provided that
an Offering Period may be terminated by the Board of Directors on any Exercise
Date if the Board determines that the termination of the Offering Period or the
Plan is in the best interests of the Company and its shareholders. Except as
provided in Section 19 and this Section 20 hereof, no amendment may make any
change in any option theretofore granted which adversely affects the rights of
any participant. To the extent necessary to comply with Section 423 of the Code
(or any successor rule or provision or any other applicable law, regulation or
stock exchange rule), the Company shall obtain shareholder approval in such a
manner and to such a degree as required.

                  (b)      Without shareholder consent and without regard to
whether any participant rights may be considered to have been "adversely
affected," the Board (or its committee) shall be entitled to change the Offering
Periods, limit the frequency and/or number of changes in the amount

                                      -8-
<PAGE>

withheld during an Offering Period, establish the exchange ratio applicable to
amounts withheld in a currency other than U.S. dollars, permit payroll
withholding in excess of the amount designated by a participant in order to
adjust for delays or mistakes in the Company's processing of properly completed
withholding elections, establish reasonable waiting and adjustment periods
and/or accounting and crediting procedures to ensure that amounts applied toward
the purchase of Common Stock for each participant properly correspond with
amounts withheld from the participant's Compensation, and establish such other
limitations or procedures as the Board (or its committee) determines in its sole
discretion advisable which are consistent with the Plan.

                  (c)      In the event the Board determines that the ongoing
operation of the Plan may result in unfavorable financial accounting
consequences, the Board may, in its discretion and, to the extent necessary or
desirable, modify or amend the Plan to reduce or eliminate such accounting
consequence including, but not limited to:

                           (i) altering the Purchase Price for any Offering
Period including an Offering Period underway at the time of the change in
Purchase Price;

                           (ii) shortening any Offering Period so that Offering
Period ends on a new Exercise Date, including an Offering Period underway at the
time of the Board action; and

                           (iii) allocating shares.

                  Such modifications or amendments shall not require stockholder
approval or the consent of any Plan participants.

         21.      NOTICES. All notices or other communications by a participant
to the Company under or in connection with the Plan shall be deemed to have been
duly given when received in the form specified by the Company at the location,
or by the person, designated by the Company for the receipt thereof.

         22.      CONDITIONS UPON ISSUANCE OF SHARES. Shares shall not be issued
with respect to an option unless the exercise of such option and the issuance
and delivery of such shares pursuant thereto shall comply with all applicable
provisions of law, domestic or foreign, including, without limitation, the
Securities Act of 1933, as amended, the Securities Exchange Act of 1934, as
amended, the rules and regulations promulgated thereunder, and the requirements
of any stock exchange upon which the shares may then be listed, and shall be
further subject to the approval of counsel for the Company with respect to such
compliance.

                  As a condition to the exercise of an option, the Company may
require the person exercising such option to represent and warrant at the time
of any such exercise that the shares are being purchased only for investment and
without any present intention to sell or distribute such shares if, in the
opinion of counsel for the Company, such a representation is required by any of
the aforementioned applicable provisions of law.

         23.      TERM OF PLAN. The Plan shall become effective upon the earlier
to occur of its adoption by the Board of Directors or its approval by the
shareholders of the Company. It shall continue in effect for a term of ten (10)
years unless sooner terminated under Section 20 hereof.

                                      -9-
<PAGE>

         24.      AUTOMATIC TRANSFER TO LOW PRICE OFFERING PERIOD. To the extent
permitted by any applicable laws, regulations, or stock exchange rules if the
Fair Market Value of the Common Stock on any Exercise Date in an Offering Period
is lower than the Fair Market Value of the Common Stock on the Enrollment Date
of such Offering Period, then all participants in such Offering Period shall be
automatically withdrawn from such Offering Period immediately after the exercise
of their option on such Exercise Date and automatically re-enrolled in the
immediately following Offering Period as of the first day thereof.

                                      -10-
<PAGE>

                                    EXHIBIT A

                                DOUBLETWIST, INC.

                        2000 EMPLOYEE STOCK PURCHASE PLAN

                             SUBSCRIPTION AGREEMENT

_____ Original Application                          Enrollment Date:___________
_____ Change in Payroll Deduction Rate
_____ Change of Beneficiary(ies)

1.       ____________________ hereby elects to participate in the DoubleTwist,
         Inc. Employee Stock Purchase Plan (the "Employee Stock Purchase Plan")
         and subscribes to purchase shares of the Company's Common Stock in
         accordance with this Subscription Agreement and the Employee Stock
         Purchase Plan.

2.       I hereby authorize payroll deductions from each paycheck in the amount
         of ____% of my Compensation on each payday (from 0 to _____%) during
         the Offering Period in accordance with the Employee Stock Purchase
         Plan. (Please note that no fractional percentages are permitted.)

3.       I understand that said payroll deductions shall be accumulated for the
         purchase of shares of Common Stock at the applicable Purchase Price
         determined in accordance with the Employee Stock Purchase Plan. I
         understand that if I do not withdraw from an Offering Period, any
         accumulated payroll deductions will be used to automatically exercise
         my option.

4.       I have received a copy of the complete Employee Stock Purchase Plan. I
         understand that my participation in the Employee Stock Purchase Plan is
         in all respects subject to the terms of the Plan. I understand that my
         ability to exercise the option under this Subscription Agreement is
         subject to shareholder approval of the Employee Stock Purchase Plan.

5.       Shares purchased for me under the Employee Stock Purchase Plan should
         be issued in the name(s) of (Employee or Employee and Spouse only).

6.       I understand that if I dispose of any shares received by me pursuant to
         the Plan within 2 years after the Enrollment Date (the first day of the
         Offering Period during which I purchased such shares) or one year after
         the Exercise Date, I will be treated for federal income tax purposes as
         having received ordinary income at the time of such disposition in an
         amount equal to the excess of the fair market value of the shares at
         the time such shares were purchased by me over the price which I paid
         for the shares. I HEREBY AGREE TO NOTIFY THE COMPANY IN WRITING WITHIN
         30 DAYS AFTER THE DATE OF ANY DISPOSITION OF MY SHARES AND I WILL MAKE
         ADEQUATE PROVISION FOR FEDERAL, STATE OR OTHER TAX WITHHOLDING
         OBLIGATIONS, IF ANY, WHICH ARISE UPON THE

<PAGE>

         DISPOSITION OF THE COMMON STOCK. The Company may, but will not be
         obligated to, withhold from my compensation the amount necessary to
         meet any applicable withholding obligation including any withholding
         necessary to make available to the Company any tax deductions or
         benefits attributable to sale or early disposition of Common Stock by
         me. If I dispose of such shares at any time after the expiration of the
         2-year and 1-year holding periods, I understand that I will be treated
         for federal income tax purposes as having received income only at the
         time of such disposition, and that such income will be taxed as
         ordinary income only to the extent of an amount equal to the lesser of
         (1) the excess of the fair market value of the shares at the time of
         such disposition over the purchase price which I paid for the shares,
         or (2) 15% of the fair market value of the shares on the first day of
         the Offering Period. The remainder of the gain, if any, recognized on
         such disposition will be taxed as capital gain.

7.       I hereby agree to be bound by the terms of the Employee Stock Purchase
         Plan. The effectiveness of this Subscription Agreement is dependent
         upon my eligibility to participate in the Employee Stock Purchase Plan.

8.       In the event of my death, I hereby designate the following as my
         beneficiary(ies) to receive all payments and shares due me under the
         Employee Stock Purchase Plan:

         NAME:  (Please print)__________________________________________________
                                   (First)             (Middle)         (Last)

         _________________________             _________________________________
         Relationship
                                               _________________________________
                                               (Address)

                                      -2-
<PAGE>

         Employee's Social
         Security Number:                ------------------------------------

         Employee's Address:             ------------------------------------

                                         ------------------------------------

                                         ------------------------------------

I UNDERSTAND THAT THIS SUBSCRIPTION AGREEMENT SHALL REMAIN IN EFFECT THROUGHOUT
SUCCESSIVE OFFERING PERIODS UNLESS TERMINATED BY ME.

Dated:_________________________        ________________________________________
                                        Signature of Employee

                                        _______________________________________
                                        Spouse's Signature (If beneficiary
                                        other than spouse)

                                      -3-
<PAGE>

                                    EXHIBIT B

                                DOUBLETWIST, INC.

                        2000 EMPLOYEE STOCK PURCHASE PLAN

                              NOTICE OF WITHDRAWAL

         The undersigned participant in the Offering Period of the DoubleTwist,
Inc. Employee Stock Purchase Plan which began on ____________, ______ (the
"Enrollment Date") hereby notifies the Company that he or she hereby withdraws
from the Offering Period. He or she hereby directs the Company to pay to the
undersigned as promptly as practicable all the payroll deductions credited to
his or her account with respect to such Offering Period. The undersigned
understands and agrees that his or her option for such Offering Period will be
automatically terminated. The undersigned understands further that no further
payroll deductions will be made for the purchase of shares in the current
Offering Period and the undersigned shall be eligible to participate in
succeeding Offering Periods only by delivering to the Company a new Subscription
Agreement.

                                   Name and Address of Participant:

                                   --------------------------------

                                   --------------------------------

                                   --------------------------------

                                   Signature:

                                   --------------------------------

                                   Date:
                                        ---------------------------

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