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EXHIBIT 10.13

                             GENOMETRIX INCORPORATED

                       NOTE AND WARRANT PURCHASE AGREEMENT

                                                    Dated as of January 24, 1996

Genometrix Incorporated
4800 Research Forest Drive
The Woodlands, TX  77381

Gentlemen:

     1.   SUBSCRIPTION. On the Closing Date (as defined herein), DONALD R.
KENDALL, JR. ("DRK") and DIANNE S. KENDALL ("DSK") as Joint Tenants with Right
of Survivorship, (collectively, the "Purchaser") hereby agrees to purchase from
Genometrix Incorporated (the "Company") a Convertible Note, in the form attached
hereto as EXHIBIT A (the "Convertible Note"), in the principal amount of
$10,000, at a purchase price equal to the principal amount thereof, to be issued
in the name of the Purchaser, and a warrant, in the form attached hereto as
EXHIBIT B (the "Warrant"), at a purchase price of $10.00 to be issued in the
name of the Purchaser. In addition, the Purchaser agrees to loan up to an
additional $20,000, pursuant to the terms and conditions set forth herein and
the form of Convertible Note attached hereto as EXHIBIT A, at any time and from
time to time during the period ending on the fifth anniversary of this
Agreement, at the option of the Company, in principal amounts of $5,000 or any
multiple thereof, upon five days prior written request from the Company to the
Purchaser. Each such additional loan shall occur on such date as the Company
shall designate in such request, subject to the provisions of Section 9. Upon
each additional loan, the Company shall deliver a Convertible Note in the
principal amount hereof in the form of Convertible Note attached hereto as
EXHIBIT A and a Warrant in the form of Warrant attached hereto as EXHIBIT B,
upon payment therefor of an amount equal to one one-thousandth (1/1000) of the
principal amount of the Convertible Note evidencing such additional loan. This
Note and Warrant Purchase Agreement is being entered into contemporaneously with
a Note and Warrant Purchase Agreement with Palmetto Partners, Ltd. in connection
with its purchase of a convertible note on substantially similar terms in the
principal amount of $90,000, and a warrant on substantially similar terms, and
their agreement to loan to the Company up to an additional $180,000 (the
"Palmetto Agreement"). Any such request must be contemporaneous with a request
under the Palmetto Agreement for $45,000 or a corresponding multiple thereof.

     2.   CLOSING DATE AND PAYMENT. The date for the purchase and sale of the
initial Convertible Note and the initial Warrant by the Company and the
Purchaser hereunder shall be as of January 24, 1996 (the "Closing Date"), the
date upon which the first advances hereunder were made. Subject to the terms and
conditions contained in this Agreement, the Purchaser shall deliver to the
Company by check or by wire transfer $10,000 in exchange for the Convertible


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Note and $10 in exchange for the Warrant.

     3.   REPRESENTATIONS AND WARRANTIES OF THE PURCHASER. The Purchaser hereby
represents and warrants, as of the date hereof as follows:

          (a)  Neither the sale of the Convertible Notes or of the Warrants nor
     the issuance of the shares of capital stock or other securities upon
     conversion or exercise thereof or upon conversion, if applicable, of such
     securities (collectively, such shares are referred to herein as the
     "Conversion Securities") has been nor will be registered under the
     Securities Act of 1933, as amended or any successor statute (the
     "Securities Act"), or any state securities laws. The Purchaser understands
     that the offering and sale of the Convertible Notes and Warrants is
     intended to be exempt from registration under the Securities Act, by virtue
     of Section 4(2) and/or Section 4(6) of the Securities Act and the
     provisions of Regulation D promulgated thereunder;

          (b)  DSK and DRK are acquiring the Convertible Notes and Warrants
     solely for their own account for investment and not with a view to resale
     or distribution and has no present intention of transferring the
     Convertible Notes or Warrants to any other person or entity;

          (c)  Each of DRK and DSK is an "accredited investor" as that term is
     defined in Rule 501 of Regulation D under the Securities Act;

          (d)  Each of DRK and DSK is a sophisticated investor and has such
     knowledge and experience in financial, tax, business matters, securities
     and investments including, without limitation, experience in investments by
     actual participation, so as to enable it to utilize the information made
     available to it in connection with the offering of the Convertible Notes
     and Warrants, to evaluate the merits and risks of an investment in the
     Convertible Notes and Warrants and to make an informed investment decision
     with respect thereto;

          (e)  This Agreement is a valid and legally binding agreement of DRK
     and DSK;

          (f)  Each of DRK and DSK has received all documents requested by him
     or her, as the case may be, and has reviewed them and believes himself or
     herself well-informed about the Company;

          (g)  Each of DRK and DSK acknowledges that neither the Securities and
     Exchange Commission nor any state securities commission has approved the
     Convertible Notes or the Warrants or any of the Conversion Securities or
     passed upon or endorsed the merits of the offering;

          (h)  Each of DRK and DSK is aware that an investment in the
     Convertible


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     Notes involves a number of very significant risks and has read and
     considered the matters set forth under the caption "Risk Factors" attached
     hereto, and, in particular, acknowledges that the Company is in the
     development stage, has no products or services, and has not commenced
     significant operations other than research;

          (i)  Each of DRK and DSK must bear the economic risk of the investment
     indefinitely because none of the Convertible Notes, Warrants or Conversion
     Securities have been registered under applicable securities laws and
     therefore, none of the Convertible Notes, Warrants or Conversion Securities
     may be sold, hypothecated or otherwise disposed of unless subsequently
     registered under the Securities Act and applicable state securities laws or
     an exemption from registration is available. The Purchaser will not sell
     any of the Convertible Notes, Warrants or Conversion Securities without
     registration under applicable securities laws or exemptions therefrom.
     Legends shall be placed on the Convertible Notes, Warrants and Conversion
     Securities to the effect that they have not been registered under the
     Securities Act or applicable state securities laws and of the resulting
     limitations on transfer and that appropriate notations thereof will be made
     in the Company's books and stock transfer records;

          (j)  The aggregate purchase price of the Convertible Notes and
     Warrants does not exceed twenty percent (20%) of DRK's and DSK's joint net
     worth;

          (k)  Neither DSK nor DRK has taken any action which would give rise to
     any claim by any person for brokerage commission, finders' fees or the like
     relating to this Agreement or the transactions contemplated hereby;

          (l)  Each of DRK and DSK represents to the Company that the
     information contained herein is accurate and may be relied upon by the
     Company in determining the availability of an exemption from registration
     under Federal and state securities laws in connection with the offering of
     the Convertible Notes, Warrants and Conversion Securities; and

          (m)  Each of DRK and DSK acknowledges that any projections and
     estimates provided to the Purchaser are based on assumptions about the
     conditions and courses of action that the Company believes are reasonable,
     that projections and estimates based on a set of different conditions and
     courses of action could differ substantially from the accompanying
     projections and estimates, that unanticipated events and circumstances may
     occur subsequent to the date that the projections and estimates were
     completed, and that therefore the actual results achieved during the
     projection and estimation period will vary from the projections and
     estimates and the variations may be material.


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     4.   REPRESENTATIONS AND WARRANTIES OF THE COMPANY. The Company hereby
represents, warrants and agrees as follows:

          (a)  ORGANIZATION, STANDING AND QUALIFICATION OF THE COMPANY. The
     Company is a corporation duly organized, validly existing and in good
     standing under the laws of the State of Delaware. The Company has all
     requisite corporate power and authority to own and operate its properties
     and to carry on its business as now being conducted and as proposed to be
     conducted. The Company is duly qualified to do business as a foreign
     corporation and is in good standing in each jurisdiction in which failure
     to so qualify would materially and adversely affect the business,
     properties, operations or condition, financial or otherwise, of the
     Company. Except as set forth on SCHEDULE A, the Company does not own and
     has not ever owned (directly or indirectly) any equity or other similar
     ownership interest in any corporation, partnership, joint venture,
     association or other entity or organization. Copies of the Company's
     Certificate of Incorporation, Bylaws and resolutions adopted by the
     directors of the Company authorizing the transactions contemplated by this
     Agreement, as set forth in EXHIBIT C are true, correct and complete copies
     thereof, have not been amended or modified in any way, have not been
     rescinded and are in full force and effect on the date hereof.

          (b)  CORPORATE AUTHORITY; ENFORCEABILITY. The Company has full right,
     power and authority to issue and sell the Convertible Notes and Warrants as
     herein contemplated and the Company has full power and authority to enter
     into and perform its obligations under this Agreement, the Convertible
     Notes and the Warrants. The execution and delivery of this Agreement, the
     Convertible Notes and the Warrants by the Company and the consummation of
     the transactions contemplated herein and therein have been duly authorized
     and approved by all requisite corporate action. The execution, delivery and
     performance of this Agreement, the Convertible Notes and the Warrants by
     the Company have been duly authorized and each of the Agreement, the
     Convertible Notes and Warrants is a valid and legally binding agreement of
     the Company.

          (c)  CONFLICTS. Neither the authorization, execution and delivery of
     this Agreement, the Convertible Notes or the Warrants nor the consummation
     of the transactions herein and therein contemplated, will (i) conflict with
     or result in a breach of any of the terms of the Company's charter or
     Bylaws (ii) violate any judgment, order, injunction, decree or award of any
     court or governmental body against or binding on the Company or to which
     its property is subject, (iii) violate any law or regulation of any
     jurisdiction which is applicable to the Company, or (iv) violate, conflict
     with or result in the breach or termination of, or constitute a default
     under, the terms of any material agreement to which the Company is a party.

          (d)  CAPITALIZATION. The total authorized capital stock of the Company
     consists of 3,000 shares of Common Stock, $.01 par value per share (the
     "Common Stock") of which 95 shares are issued and outstanding. All of the
     outstanding shares of Common Stock have been duly authorized, validly
     issued and are fully paid and nonassessable. Except as


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     set forth on SCHEDULE A and pursuant to the Palmetto Agreement, there are
     no options, warrants or rights to purchase shares of Common Stock or other
     securities (as defined herein) of the Company authorized, issued or
     outstanding, nor is the Company obligated in any other manner to issue
     shares of its capital stock or other securities. Except as set forth on
     SCHEDULE A, the Company is under no obligation (contingent or otherwise) to
     purchase or otherwise acquire or retire any of its outstanding securities.
     Unless the context otherwise requires, as used herein, the term
     "securities" and "security" shall have the meaning given such term in the
     Securities Act.

          (e)  LITIGATION. There are no actions, suits or proceedings at law or
     in equity or by or before any governmental instrumentality or other agency
     or regulatory authority now pending, or, to the best knowledge of the
     Company, threatened against the Company which, if adversely determined,
     could materially and adversely affect the business, assets, operations or
     condition, financial or otherwise, of the Company.

          (f)  COMPLIANCE WITH LAWS. To the Company's knowledge, the Company is
     not in violation of any statute, law, rule or regulation, or in default
     with respect to any judgment, writ, injunction, decree, rule or regulation
     of any court or governmental agency or instrumentality, except for such
     violations or defaults which do not materially and adversely affect the
     business, assets, operations or condition, financial or otherwise, of the
     Company.

          (g)  GOVERNMENTAL CONSENTS. Subject to the accuracy of the
     representations and warranties of the Purchaser set forth herein, no
     registration or filing with, or consent or approval of or other action by,
     any Federal, state or other government agency under laws and regulations
     thereof as now in effect is or will be necessary for the valid execution,
     delivery and performance by the Company of this Agreement, the Convertible
     Notes or the Warrants and the issuance, sale and delivery of the
     Convertible Notes and Warrants, other than the filing of a Form D with the
     Securities and Exchange Commission and the filings required by state
     securities law (all of which filings have been made by the Company or will
     be made within the period of time required by such securities laws).

          (h)  CHARACTERISTICS OF SECURITIES. The stockholders of the Company
     have no preemptive rights or other purchase rights with respect to the sale
     of the Convertible Notes or Warrants or except as set forth on SCHEDULE A,
     the issuance or sale of any other securities of the Company previously
     issued or to be issued in the future.

          (i)  DIRECTORS AND OFFICERS; STOCKHOLDERS. A true and correct list of
     the directors and officers of the Company, all of whom have been duly and
     properly elected to the positions set forth opposite their respective
     names, is attached hereto as SCHEDULE B. A true and correct list of the
     record holders of all securities of the Company, setting forth their names,
     addresses and number and kind of securities held by each, is attached
     hereto as SCHEDULE C. Except as set forth on SCHEDULE A, to the knowledge
     of the Company, there exists no voting trust, voting agreement or other
     similar arrangement among any of


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     the beneficial holders of the Company's securities.

          (j)  OBLIGATIONS BETWEEN CERTAIN PERSONS AND THE COMPANY. Except as
     set forth in SCHEDULE A, the Company does not have any direct or indirect
     obligation or liability to any person listed in SCHEDULE B or C or to any
     affiliate (as defined herein) of any such person. As used herein, the term
     "affiliate" shall have the meaning given such term under the Securities
     Act.

          (k)  FINANCIAL POSITION.

               (i)  The Company has delivered to the Purchaser the financial
          statements (the "Financial Statements") which are annexed hereto as
          SCHEDULE D. The Financial Statements (A) present fairly the financial
          condition of the Company as of their respective dates and results of
          operations for the periods then ended, (B) are in accordance with the
          books and records of the Company and (C) were prepared in accordance
          with generally accepted accounting principles consistently applied
          except that footnote disclosures contemplated by generally accepted
          accounting principles are not provided.

               (ii) At the date of the most recent balance sheet (the "Balance
          Sheet") contained in the Financial Statements, (A) the Company had no
          liabilities of any nature (matured or unmatured, fixed or contingent)
          required by generally accepted accounting principles to be provided
          for in the Balance Sheet or described in the notes thereto which were
          not provided for in the Balance Sheet or described in the notes
          thereto and (B) all reserves established by the Company and set forth
          in the Balance Sheet were adequate for the purposes for which they
          were established.

               (iii) Except as set forth on SCHEDULE A and as contemplated by
          the Palmetto Agreement, since the date of the Balance Sheet:

                    (A)  the Company has not entered into any transaction which
               was not in the ordinary course of its business,

                    (B)  there has been no material adverse change in the
               condition (financial or otherwise) of the Company,

                    (C)  the Company has not declared or paid any dividend or
               made any distribution on its securities, redeemed, purchased or
               otherwise acquired any of its securities, granted any options to
               purchase any securities or issued any securities,

                    (D)  the Company has not increased the compensation of any
               of its officers or the rate of pay of its employees as a group,
               by more than five percent (5%) over the prior year's
               compensation,


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                    (E)  there has been no borrowing by the Company or agreement
               to borrow or change in the contingent obligations of the Company
               by way of guaranty, endorsement, indemnity, warranty or otherwise
               or grant of a mortgage or security interest in any properties of
               the Company,

                    (F)  there have been no loans made by the Company to its
               shareholders, employees, officers, directors or any affiliate
               thereof other than travel advances and office advances made in
               the ordinary course of business,

                    (G)  there has not been any payment of any obligation or
               liability other than current liabilities paid in the ordinary
               course of business,

                    (H)  there has been no sale, assignment or transfer of any
               tangible asset of the Company except in the ordinary course of
               business and no sale, assignment or transfer of any patent,
               trademark, trade secret or other intangible asset of the Company,

                    (I)  there has been no damage to, destruction of or loss of
               physical property (whether or not covered by insurance) which may
               have a material adverse effect on the business or operations of
               the Company,

                    (J)  the Company has not received notice that there has been
               a loss to, nor cancellation of a material order by, any customer
               of the Company, and

                    (K)  there has been no resignation or termination of
               employment of any officer or employee of the Company.

               (iv) The Company has good and marketable title to the properties
          and assets purported to be owned by it and such properties and assets
          are not subject to any liens, mortgages, pledges, encumbrances or
          charges of any kind except liens for current taxes and assessments not
          delinquent or those which are not material in scope or amount and do
          not materially interfere with the conduct of the Company's business.

          (l)  MATERIAL CONTRACTS. SCHEDULE E contains a true and complete list
     of all contracts, agreements, commitments or undertakings of any nature,
     written or oral, of the Company each of which involves future payments,
     performance of services or delivery of goods or materials to or by the
     Company of an aggregate amount or value in excess of $10,000 or which
     otherwise is material to the business or prospects of the Company (other
     than the Palmetto Agreement)


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     (collectively, the "Material Contracts"). All of the Material Contracts of
     the Company are in full force and effect and the Company has fully
     performed all of its obligations thereunder. To the Company's knowledge, no
     party to a Material Contract has made a claim to the effect that the
     Company has failed to perform an obligation thereunder. There is no known
     plan, intention or indication of any contracting party to a Material
     Contract to cause the termination, cancellation or modification of such
     Material Contract or to reduce or otherwise change its activity thereunder
     so as to adversely affect the benefits derived or expected to be derived
     therefrom by the Company. Except as more particularly described in Schedule
     E, the Company does not now have in effect any bonus, profit sharing,
     pension, deferred compensation or similar plan or agreement for the benefit
     of any of its employees. The Company is neither a party to, nor bound by,
     any contract, agreement, commitment or restriction which obligates the
     Company to perform services or to produce products unprofitably, provided,
     however, that no representation is made that the Company's performance of
     its obligations under the License Agreement and the Collaboration Agreement
     (each as defined on SCHEDULE E) will be profitable to the Company. All
     nonmaterial contracts of the Company do not in the aggregate represent a
     material portion of the liabilities of the Company.

          (m)  LICENSES, PATENTS, TRADEMARKS.

               (i)  SCHEDULE F contains a list of all licenses, patents,
          copyrights, trade names and trademarks (including applications
          therefor) owned by the Company. To the Company's knowledge, the
          Company owns, free and clear of all liens and encumbrances, all the
          licenses, patents, copyrights, trade names, trademarks, trade secrets
          and processes necessary for the conduct of its business as presently
          conducted and as presently proposed to be conducted and except as
          described in SCHEDULE F, has the unrestricted right to use the
          foregoing without the payment of any royalty. The Company has taken
          reasonable security measures to protect the secrecy, confidentiality
          and value of its trade secrets and other technical information. Each
          current and former employee and consultant of the Company who is or
          was involved in research, development or technological matters has
          executed an agreement pursuant to which each such employee and
          consultant has agreed that they have no ownership or other interest in
          any patents, inventions or other proprietary processes created by them
          in the course of their employment by or consultation to the Company.

               (ii) To the Company's knowledge, no person has asserted a claim
          that the Company has infringed any patent, trade secret, copyright,
          trade name or trademark. To the Company's knowledge, the Company does
          not, and will not under its proposed plan of business, operate to
          conflict with, infringe, override or interfere with the rights of any
          other person in any license, patent, trade name, trademark, trade
          secret or process or rights pertaining thereto.


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               (iii) All rights to processes, systems, patents and techniques
          used by the Company which were developed by any employee of or
          consultant to the Company in the course of providing services to the
          Company have been duly and validly assigned to the Company.

          (n)  EXISTENCE OF DEFAULTS. The Company is not in default of any of
     its material obligations, and no event has occurred and is continuing under
     the provisions of any instrument, document or agreement which, with the
     lapse of time or the giving of notice or both, would constitute a default
     thereunder.

          (o)  TAX RETURNS AND PAYMENTS. All tax returns and reports required to
     be filed with respect to the Company have been duly filed and all taxes
     shown to be due and payable on such returns and reports, and all tax
     assessments, have been paid or provision has been made therefor. The
     Company has paid all taxes which it is obligated to withhold from amounts
     owing to any employee. The Company does not know of any proposed assessment
     for additional taxes or of any basis therefor.

          (p)  FINDER OR BROKER. Neither the Company nor any person acting on
     behalf of the Company has negotiated with any finder, broker, intermediary
     or any similar person in connection with the transactions contemplated
     herein. The Company will indemnify the Purchaser and hold it harmless from
     any liability or expense arising from any claim for brokerage commissions,
     finder's fees or other similar compensation based upon any agreement,
     arrangement or understanding made by or on behalf of the Company.

          (q)  CONFLICTING INTEREST. Except as set forth on SCHEDULE A, no
     officer, director or stockholder of the Company has any interest in any
     corporation, partnership or other entity engaged in a business which is in
     competition with that of the Company or which is a supplier of products to
     the Company or has any contract with the Company.

          (r)  EMPLOYEES AND CONSULTANTS.

               (i)  To the knowledge of the Company, no employee or consultant
          of the Company is in violation of any term of any employment or
          consulting contract, patent disclosure agreement or any other contract
          or agreement relating to the right of any such employee or consultant
          to be employed or engaged by the Company because of the nature of the
          business conducted or to be conducted by the Company or for any other
          reason, and to the knowledge of the Company, the continued employment
          or engagement by the Company of its present employees or consultants
          will not result in any violations.

               (ii) The Company has eight (8) employees.

               (iii) The Company is not aware that any officer, director,
          executive


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          or key employee of the Company or any group of employees of the
          Company has any plan or intention of terminating employment or
          association with the Company.

          (s)  TRUTH AND COMPLETENESS OF REPRESENTATIONS AND WARRANTIES. Neither
     this Agreement nor any exhibit or schedule to this Agreement, or schedule
     or document furnished by the Company or its officers in connection with the
     transactions contemplated herein contains any untrue statement of any
     material fact or omits to state a material fact necessary in order to make
     the statements contained therein or herein, in light of the circumstances
     under which they were made, not misleading; and there is no fact specific
     to the Company which materially and adversely affects the business,
     prospects, affairs, operations or condition, financial or otherwise, of the
     Company which has not been disclosed to the Purchaser (other than
     information about the healthcare, pharmaceutical, biotechnology, computer
     or microelectronic industry in general or general economic conditions which
     information is generally available to the public) by the Company. The
     foregoing representation is not intended to include facts pertaining
     generally to the industries the Company intends to operate within, general
     economic, political or regulatory conditions or facts generally applicable
     to start-up companies. The projections and estimates provided to the
     Purchaser were prepared in good faith and with a good faith belief in the
     reasonableness of the assumptions on which the projections and estimates
     were based, but the Company makes no other representation or warranty with
     respect to such projections or estimates in any manner. The representations
     and warranties of the Company are complete and accurate in all material
     respects.

          As used in this Section 4, "knowledge," "know" or "known," when
     referring to the Company, shall refer to the knowledge of officers and
     directors of the Company, but shall not include inquiry of other persons or
     entities.

     5.   AFFIRMATIVE COVENANTS OF THE COMPANY. From and after the Closing Date
and until the Conversion Date (as defined in the Convertible Notes), unless it
receives the prior written consent of the Purchaser to act to the contrary, the
Company shall comply with the covenants contained in this Section 5 so long as
there remains outstanding the Convertible Note. For purposes of this Section,
the term "Company" shall be deemed to include, in addition to the Company, all
Subsidiaries


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          (a)  FINANCIAL INFORMATION. The Company shall maintain a system of
     accounting established and administered in accordance with generally
     accepted accounting principles consistently applied, and shall set aside on
     its books, and cause each of its operating subsidiaries to set aside on its
     books, all such proper reserves as shall be required by generally accepted
     accounting principles. The Company shall retain independent certified
     public accounts of recognized national standing who shall audit the
     Company's financial statements at the end of each fiscal year. In the event
     the services of the independent public accountants so selected, or any firm
     of independent public accounts hereafter employed by the Company are
     terminated, the Company shall promptly thereafter notify the Purchaser and
     shall request the firm of independent certified public accountants whose
     services are terminated to deliver to the Purchase a letter of such firm
     setting forth the reasons for the termination of their services. In the
     event of such termination, the Company shall promptly thereafter engage
     another such firm of independent certified public accountants of recognized
     national standing. In its notice to the Purchaser, the Company shall state
     whether the change of accountants was recommended or approved by the Board
     of Directors of the Company or any committee thereof. The Company will
     furnish the following reports to the Purchaser:

               (i)  As soon as practicable after the end of each fiscal year,
          and in any event within 120 days thereafter, a consolidated balance
          sheet of the Company and its Subsidiaries (as defined below) (if any)
          as of the end of such fiscal year, and a consolidated statement of
          income and a consolidated statement of changes in financial position
          of the Company for such year, prepared in accordance with generally
          accepted accounting principles consistently applied and setting forth
          in each case in comparative form the figures of the previous fiscal
          year, all in reasonable detail including all supporting schedules and
          comments. If the Company has retained an auditor, such financial
          statements shall be accompanied by the opinion of such auditors with
          respect to such financial statements.

               (ii) As soon as practicable after the end of each month, and in
          any event within 15 days thereafter, (A) a consolidated balance sheet
          of the Company and its Subsidiaries (if any) as of the end of such
          month, and a consolidated statement of income, shareholder's equity
          and cash flow for each month and for the current fiscal year to date,
          prepared in accordance with generally accepted accounting principles
          consistently applied and (B) a letter from the chief executive officer
          of the Company reporting on the Company's operations, describing
          significant events or circumstances affecting operations and
          containing such other matters as are reasonably requested by the
          Purchaser

          (b)  ADDITIONAL INFORMATION. The Company will furnish to the
     Purchaser:


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<PAGE>   12


               (i)  Concurrently with the delivery of each of the financial
          statements referred to in Section 5(a) above, a certificate executed
          by the president or chief financial officer of the Company stating
          that neither the Company nor any of its Subsidiaries is in default
          under its certificate of incorporation, its by-laws, this Agreement,
          the Convertible Notes, the Warrants or any other material agreements
          to which it is a party or to which it or any of its properties is
          subject;

               (ii) Promptly following receipt thereof, any letters furnished to
          the Company by its independent public accountants which comment on the
          accounting practices of the Company;

               (iii) Promptly (but in any event within five days) after the
          discovery of any material adverse event or circumstance affecting the
          Company including, but not limited to, the filing of any material
          litigation against the Company or any Subsidiary and the discovery
          that the Company is not, or with the passage of time will not be, in
          compliance with any provision of this Agreement, the Convertible
          Notes, the Warrants, its Certificate of Incorporation or any other
          material agreement of the Company, a notice specifying the nature and
          period of existence thereof, and the actions the Company has taken
          and/or proposes to take with respect thereto. The Company shall
          furnish the Purchaser with monthly reports updating and describing any
          developments relating to matters described under this subparagraph
          (iii) and will promptly notify the Purchaser of any material
          developments or changes relating thereto. "Subsidiary" as used in this
          Agreement shall mean as to the Company, any corporation of which more
          than 50% of the outstanding stock having ordinary voting power to
          elect a majority of the Board of Directors of such corporation is at
          the time directly or indirectly owned by the Company, or by one or
          more of its Subsidiaries, or by the Company and one or more of its
          Subsidiaries;

               (iv) Promptly following the preparation thereof, copies of the
          minutes of proceedings (or consents) of the Company's Board of
          Directors and stockholders together with all written materials given
          to investors in connection with any meeting of the Board of Directors;
          and

               (v)  With reasonable promptness, such other information and data
          with respect to the Company and its Subsidiaries as the Purchaser may
          from time to time reasonably request.

     The provisions of this Section 5(b) shall not be in limitation of any
rights which the Purchaser may have with respect to the books of account and
records of the Company and its subsidiaries (if any) or to inspect their
properties and assets or discuss their affairs, finances and accounts, under the
laws of the respective jurisdictions in which the Company and its subsidiaries
(if any) are incorporated.


                                      -12-
<PAGE>   13


          (c)  INSPECTION. The Purchaser shall have the right, at its expense,
     to visit and inspect any of the properties of the Company or any of its
     Subsidiaries and to discuss its affairs, finances and accounts with its
     officers, directors and independent public accountants, all at such
     reasonable times and as often as may be reasonably requested.

          (d)  USE OF PROCEEDS. The Company shall use the net cash proceeds of
     the sale of the Convertible Notes and Warrants for working capital.

          (e)  INSURANCE. The Company has in full force and effect the insurance
     as described on Schedule G.

          (f)  COMPLIANCE WITH CERTIFICATE OF INCORPORATION, BYLAWS AND
     AGREEMENTS. The Company shall perform and observe all of its obligations
     pursuant to its Certificate of Incorporation, its Bylaws, this Agreement,
     the Convertible Notes, the Warrants, and the Material Contracts.

          (g)  REGISTRATION OF TRANSFER. The Company shall keep at its principal
     office (or such place as the Company reasonably designates) a register for
     the registration of the outstanding securities of the Company. Upon
     surrender of any promissory note (including without limitation the
     Convertible Notes) properly endorsed for transfer, the Company shall, at
     the request of the holder of such security, execute and deliver a new
     promissory note, in exchange therefor, representing the aggregate principal
     amount of the surrendered notes, and the Company forthwith shall cancel
     such surrendered note. Each such new note shall be registered on the books
     of the Company in such name and shall (subject to the immediately preceding
     sentence) represent such principal amount of note as is requested by the
     holder of the surrendered note and shall be substantially identical in form
     to the surrendered note, subject to the restrictions stated in the legend
     set forth on the Convertible Notes, which legend shall be placed on, and
     which restrictions shall apply to, all notes issued in replacement
     therefor. The issuance of new notes shall be made without charge to the
     holders of the surrendered note or new note for any issuance tax in respect
     thereof or other cost incurred by the Company in connection with such
     issuance or transfer.

          (h)  REPLACEMENT. The Company shall issue a new note in place of any
     previously issued note alleged to have been lost, stolen or destroyed, upon
     such terms and conditions as the Board of Directors may prescribe,
     including the presentation of reasonable evidence of such loss, theft or
     destruction (provided that an affidavit of a holder will be satisfactory
     for such purpose) and the giving of such indemnity as the Company's Board
     of Directors may request for the protection of the Company or any transfer
     agent or registrar (provided that if the holder is the Purchaser, its own
     indemnification agreement in form reasonably satisfactory to the Company
     shall under all circumstances be satisfactory, and no bond shall be
     required). Upon surrender of any previously issued note that has been
     mutilated, the Company shall issue a new note in


                                      -13-
<PAGE>   14


     place thereof.

          (i)  MAINTENANCE OF CORPORATE EXISTENCE AND BUSINESS. The Company
     shall take such action as may from time to time be necessary to preserve
     its corporate existence, rights and franchises, maintain its properties in
     good repair and to comply with the laws of the United States and all states
     and locations in which the Company shall do business as shall be necessary
     to permit the Company to conduct its business, and to preserve all of its
     rights, franchises and privileges.

          (j)  TAXES AND OTHER OBLIGATIONS. The Company shall pay and discharge
     all taxes, assessments, interest and installments on mortgages and
     governmental charges against it or against any of its properties, upon the
     respective dates when due, except to the extent that (a) such taxes,
     assessments, interest, installments and governmental charges are contested
     in good faith and by appropriate proceedings in such manner as not to cause
     any materially adverse effect on its financial condition or loss of any
     right of redemption from any sale and (b) the Company shall have set aside
     on its books reserves (segregated to the extent required by generally
     accepted accounting principles) adequate with respect to such liabilities.

          (k)  COMPLIANCE WITH LAWS. The Company shall comply with applicable
     laws, rules and regulations of all governmental authorities, the violation
     of which might have a material adverse effect upon its business or
     financial condition.

          (l)  AGREEMENTS WITH EMPLOYEES AND CONSULTANTS. The Company shall
     cause all employees and consultants of the Company who may become involved
     in research, development or technological matters to execute an agreement
     pursuant to which each such employee and consultant will agree that they
     have no ownership or other interest in any patents, inventions or other
     proprietary processes created by them during their employment by or in the
     course of their consultation to the Company.

          (m)  BOARD OF DIRECTORS VISITATION RIGHTS. The Company shall give the
     Purchaser prior notice of each meeting of the Board of Directors of the
     Company in accordance with the notice requirements applicable to the Board
     of Directors as set forth in the By-laws of the Company and a
     representative of the Purchaser shall be invited to attend as a non-voting
     observer all such meetings even if a representative of the Purchaser does
     not at the time serve as a member of the Board of Directors. The Company
     shall pay all normal and reasonable travel, food and lodging expenses
     incurred or paid by one representative of the Purchaser (whether or not
     such representative is on the Board of Directors) in connection with their
     attendance at such meetings that are held in a city other than Houston,
     Texas or The Woodlands, Texas. The Company shall promptly give the
     Purchaser copies of all materials and documents furnished to the Board of
     Directors in connection with such meetings.

          (n)  SUBORDINATION. All Junior Indebtedness (as defined herein)
     incurred by the


                                      -14-
<PAGE>   15


     Company subsequent to the date hereof shall be subordinated to the
     indebtedness evidenced by the Convertible Notes in a manner that is
     reasonably satisfactory to the Purchaser. As used herein, the term "Junior
     Indebtedness" shall mean any indebtedness of the Company that is evidenced
     by a note or other similar instrument and that is not owed to a commercial
     bank or other similar financial institution.

          (o)  FURTHER ASSURANCES. The Company shall execute, acknowledge and
     deliver, or cause to be executed, acknowledged and delivered, to the
     Purchaser such further and additional instruments and documents and shall
     use its best efforts to cause to be taken such other action as the
     Purchaser reasonably may require to more effectively implement and carry
     into effect the transactions contemplated by this Agreement.

          (p)  AVAILABILITY OF COMMON STOCK FOR CONVERSION. The Company
     shall, from time to time, in accordance with the laws of the State of
     Delaware, take such actions (within its control) as are necessary to
     increase the authorized amount of Common Stock if at any time the number of
     shares of Common Stock remaining unissued and available for issuance shall
     be insufficient to permit conversion of all the then outstanding
     Convertible Notes and Warrants of the Company.

     6.   NEGATIVE COVENANTS OF THE COMPANY. From and after the Closing Date and
until the Conversion Date, unless it receives the prior written consent of the
Purchaser to act to the contrary, the Company shall comply with the covenants
contained in this Section 6 so long as the Convertible Notes remain outstanding.
For purposes of this Article, the term "Company" shall be deemed to include, in
addition to the Company, all Subsidiaries. Subject to the foregoing, the Company
agrees as follows:

          (a)  INDEBTEDNESS. The Company shall not guarantee the obligation of
     another person (except of wholly-owned Subsidiaries) and will not make any
     loan or advance to any person or entity (except wholly-owned Subsidiaries)
     except moving expenses, advances and similar expenditures in the ordinary
     course of business.

          (b)  INVESTMENTS. The Company will not invest (as a shareholder,
     partner, lender or otherwise) in any other corporation, except a wholly
     owned Subsidiary; provided, however, the foregoing prohibition shall not
     prevent the Company from purchasing short term money market instruments.

          (c)  MERGER, CONSOLIDATION, SALE OF ASSETS, ETC. The Company shall
     not, and shall not permit its subsidiaries (if any), to, together or alone,
     enter into any transaction of merger, consolidation or reorganization, or
     dissolve, wind up or liquidate, or convey, sell, lease, exchange, transfer
     or otherwise dispose of in a transaction or related series of transactions
     any of its respective property, business or assets having in the aggregate
     a fair market value of more than fifty percent (50%) of the book value of
     the Company's assets on a consolidated basis or permit any subsidiary of
     the Company whose property, business or assets satisfy the foregoing test
     to enter into any transaction of merger,


                                      -15-
<PAGE>   16


     consolidation or reorganization; provided, however, that notwithstanding
     the foregoing, (i) any subsidiary of the Company may be merged or
     consolidated with or into the Company or with or into any one or more
     wholly owned subsidiaries of the Company and (ii)( any subsidiary of the
     Company may sell, lease, exchange, transfer or otherwise dispose of any or
     all of its assets (upon voluntary liquidation or otherwise) to the Company
     or a wholly owned subsidiary of the Company. The provisions of this Section
     6(c) are in addition to and are not limited by any of the terms of any
     other covenant contained herein.

          (d)  PURCHASE OF CAPITAL STOCK. The Company will not directly or
     indirectly purchase, acquire, redeem or retire any share of its outstanding
     capital stock or any securities exercisable for, or convertible into, its
     capital stock, except of shares held by a stockholder out of proceeds of
     any life insurance policy on such stockholder's life.

          (e)  DIVIDENDS. The Company shall not pay or declare any dividends or
     make other distributions upon its shares of capital stock.

          (f)  SUBSIDIARIES. The Company shall not create, own or otherwise
     acquire or hold any Subsidiary, unless it is wholly owned by the Company.

          (g)  COMPENSATION. The Company shall not pay any compensation, direct
     or indirect, to any person unless such compensation is reasonable in view
     of his or her time and efforts. Such compensation may include the issuance
     of stock options. No fees shall be paid any full-time employee for serving
     as a director of the Company.

          (h)  INSIDER TRANSACTIONS. The Company shall not engage in any
     transaction with any of the Company's directors, officers, employees or
     stockholders except (i) reimbursements of reasonable moving expenses and
     reasonable expenses incurred in the ordinary course of business, (ii)
     except as disclosed in SCHEDULE A, as provided in employment contracts
     which are terminable by the Company without penalty upon not more than 30
     days' notice or (iii) in accordance with Subsection (g) immediately above.

          (i)  NO CONFLICTING AGREEMENTS OR ACTIONS. The Company shall not enter
     into any agreement or make any amendment to any agreement or take any other
     action which would restrict or adversely affect the Company's performance
     of its obligations to the Purchaser under its Certificate of Incorporation,
     the Convertible Notes, the Warrants, its By-laws, this Agreement or any
     agreement referred to herein.

          (j)  SUBSEQUENT OFFERINGS. The Company shall not hereafter sell, offer
     for sale or solicit offers to buy any securities so as to cause the offer
     of the Convertible Notes and Warrants to violate the Securities Act or
     state securities laws or jeopardize compliance by the Company under the
     Securities Act or state securities laws in respect of future offerings of
     securities. In connection with future offerings of securities of the
     Company, the Company will comply with all federal and state securities
     laws. The Company will


                                      -16-
<PAGE>   17


     not (i) make a public offering of any of its securities other than in a
     registered offering under the Securities Act, or (ii) grant preemptive
     rights to its stockholders generally in respect of future issuances of
     equity securities.

          (k)  CONFIDENTIALITY. The Company shall not disclose any proprietary
     information to any person other than as shall be necessary to the conduct
     of the ordinary business of the Company (e.g., patent applications or
     research agreements with academic institutions which customarily refuse to
     execute confidentiality agreements) unless the Company has the written
     agreement of the party to whom the disclosure is made to retain the
     confidentiality of the Company's proprietary information and not to
     disclose it to others.

          (l)  NO CHANGE IN BUSINESS. The Company shall not make any changes in
     the character of its business as presently conducted or as proposed to be
     conducted, or conduct its business in a manner other than in the normal and
     ordinary course.

     7.   REGISTRATION RIGHTS AND SUBSEQUENT AGREEMENTS. If at any time prior to
or on the Conversion Date, the Company grants one or more persons registration
rights with respect to the registration of securities under the Securities Act,
the Purchaser shall be entitled to registration rights in respect of all
securities of the Company now owned or hereafter acquired by the Purchaser as
comparable as possible to those rights granted by the Company to such other
person(s). If at any time prior to or on the Conversion Date, different
registration rights are granted by the Company to more than one person, the
Purchaser shall be entitled to those rights which have been granted which the
Purchaser, in its sole discretion, determines are the most favorable. The
Company agrees with the Purchaser that the Purchaser will be entitled to the
benefits of affirmative and negative covenants on the same terms and conditions
as and together with the purchaser or purchasers in the Financing (as defined in
the Convertible Notes).

     8.   STAND-STILL AGREEMENT. The Purchaser agrees it will not sell, transfer
or otherwise dispose of any securities of the Company during the period
commencing upon the date upon which the Company files a registration statement
with the Securities and Exchange Commission for the registration of any
securities for sale to the public and terminating on the 180th day following the
date on which the Company's registration statement with respect to its initial
public offering is declared effective.

     9.   CONDITIONS TO CLOSING.

          (a)  CONDITIONS TO THE PURCHASER'S OBLIGATIONS. The Purchaser's
     obligation to purchase the Convertible Note and Warrant is subject to the
     following conditions:

               (i)  The Company's representations and warranties contained in
          Section 4 shall be true and correct on and as of the Closing Date
          (subject to any updated schedules provided to the Purchaser) and the
          Purchaser shall have received a certificate of the President of the
          Company with respect thereto;


                                      -17-
<PAGE>   18


               (ii) The Company shall deliver to the Purchaser an executed
          Convertible Note in the form attached hereto as EXHIBIT A; and

               (iii) The Company shall deliver to the Purchaser an executed
          Warrant in the form attached hereto as EXHIBIT B.

          (b)  CONDITIONS TO THE COMPANY'S OBLIGATIONS. The Company's obligation
     to issue any Convertible Note and Warrant is subject to the following
     conditions:

               (i)  The Purchaser's representations and warranties contained in
          Section 3 shall be true and correct on and as of the Closing Date and
          with respect to any closing after the date hereof, the Company shall
          have received a certificate of the Purchaser with respect thereto; and

               (ii) The Purchaser shall have delivered to the Company the
          purchase price for the Convertible Note, the principal amount thereof,
          and $90 as the purchase price for the Warrant being purchased
          hereunder.

     10.  PAYMENT OF LEGAL FEES. The Company shall pay the reasonable fees and
expenses of counsel to the Purchaser, incurred in connection with the
negotiation of this Agreement and the consummation of the transactions
contemplated thereby, not to exceed an aggregate of $4,000.

     11.  BINDING EFFECT. This Agreement shall be binding upon and inure to the
benefit of the parties hereto and their successors and permitted assigns
including, without limitation, transferees of the Convertible Notes, Warrants or
any of the Conversion Securities.

     12.  AMENDMENT. The terms of this Agreement shall not be amended or
modified except by a writing signed by the parties hereto.

     13.  NOTICES. Any notice or other communication required or permitted to be
given hereunder shall be in writing and shall be mailed by certified mail,
return receipt requested, or delivered against receipt to the party to whom it
is to be given (a) if to Company, to Genometrix Incorporated, 3608 Research
Forest Drive, Suite B7, The Woodlands, TX 77381, Attn: President, or (b) if to
the Purchaser, to Palmetto Partners, Ltd., 1600 Smith Street, 50th Floor,
Houston, Texas 77002 (or, in either case, to such other address as the party
shall have furnished in writing in accordance with the provisions of this
Section 13). Any notice or other communication given by certified mail shall be
deemed given at the time of certification thereof, except for a notice changing
a party's address which shall be deemed given at the time of receipt thereof.

     14.  ASSIGNABILITY. This Agreement and the rights, interests and
obligations hereunder are not transferable or assignable by the Purchaser,
provided, however, that the rights contained


                                      -18-
<PAGE>   19


in Sections 5 (other than subsection (m)), 6 and 7 may be transferred and
assigned with any transfer or assignment of a Convertible Note, provided, (i)
the transferee or assignee (a) agrees to be bound by Sections 8 and 16 hereof
and (b) is not, in the Company's reasonable judgment, a competitor of the
Company; and (ii) such transfer or assignment is made (a) in connection with a
distribution to the Purchaser's beneficial owners, affiliates (as defined in the
Securities Act) or its employees, provided one person is designated as the agent
of the transferees or assignees for purposes of their rights hereunder and
compliance with the provisions of this Agreement with respect to such agent
shall be treated as compliance with respect to all such transferees or assignees
and the Company or (b) to a transferee or an assignee who shall acquire
Convertible Notes in their entire then outstanding aggregate principal and
accrued interest amount. The Purchaser further agrees that the transfer or
assignment of the Convertible Notes, the Warrants or the Conversion Securities
shall be made only in accordance with all applicable laws.

     15.  APPLICABLE LAW. This Agreement shall be governed by and construed in
accordance with the internal law of the State of Texas without regard to its
conflicts of laws principles.

     16.  CONFIDENTIALITY. Each of DRK and DSK acknowledges and agrees that any
information or data it has acquired from or about the Company, not otherwise
properly in the public domain, was received in confidence. Each of DRK and DSK
agrees not to divulge, communicate or disclose, except (i) as may be required by
law or for the performance or enforcement of this Agreement, (ii) as may be
required by court order or (iii) to the extent it is already publicly available,
or acquired without breach by DRK or DSK of the terms hereof, or use other than
in connection with its investment in the Company, any confidential information
of the Company, including any scientific, technical, trade or business secrets
of the Company and any scientific, technical, trade or business materials that
are treated by the Company as confidential or proprietary, including, but not
limited to, ideas, discoveries, inventions, developments and improvements
belonging to the Company and confidential information obtained by or given to
the Company about or belonging to third parties.

     17.  MISCELLANEOUS.

          (a)  This Agreement together with the Convertible Notes and the
     Warrants constitute the entire agreement between the Purchaser and the
     Company with respect to the subject matter hereof and supersedes all prior
     oral or written agreements and understandings, if any, relating to the
     subject matter hereof, provided, however, any agreement pertaining to
     confidentiality is not superseded and shall remain in full force and effect
     and provided, further, the Note and Warrant Purchase Agreement dated July
     6, 1994 between the parties is not superseded. The terms and provisions of
     this Agreement may be waived, or consent for the departure therefrom
     granted, only by a written document executed by the party entitled to the
     benefits of such terms or provisions.

          (b)  The representations, warranties, covenants and agreements of the
     parties made in this Agreement shall survive the execution and delivery
     hereof and of the


                                      -19-
<PAGE>   20


     Convertible Notes and Warrants.

          (c)  This Agreement may be executed in one or more counterparts each
     of which shall be deemed an original, but all of which shall together
     constitute one and the same instrument.

          (d)  Each provision of this Agreement shall be considered separable
     and if for any reason any provision or provisions hereof are determined to
     be invalid or contrary to applicable law, such invalidity shall not impair
     the operation of or affect the remaining portions of this Agreement.

          (e)  Paragraph titles are for descriptive purposes only and shall not
     control or alter the meaning of this Agreement as set forth in the text.

          (f)  The Company acknowledges and agrees that the Purchaser has made
     no representation, warranty or covenant regarding Purchaser's providing of,
     and Purchaser has no obligation to provide, future financing of any kind,
     nor has Purchaser made any commitment to make loans to or to purchase any
     equity securities from the Company, except as expressly set forth herein.

          (g)  This Agreement sets forth, reduces to writing and supersedes in
     all respects the statements of the parties first set forth in the term
     sheet styled "Genometrix Incorporated Bridge Note Financing Palmetto
     Partners January 24, 1996," as executed by Palmetto Partners, Ltd. and the
     Company, and such term sheet shall hereafter by without force or effect,
     having been superseded by this Agreement. This Agreement is executed as of
     the date set forth below, but is intended to be effective for all purposes
     as of January 24, 1996.


                  [Remainder of Page Left Intentionally Blank]


                                      -20-
<PAGE>   21


     IN WITNESS WHEREOF, the Purchaser has executed this Agreement this 21st day
of January, 1997, but effective for all purposes as of January 24, 1996.


                                              /s/ Donald R. Kendall
                                              ----------------------------------
                                              Donald R. Kendall, Jr.
                                              Joint Tenant with Right of
                                              Survivorship


                                              /s/ Dianne S. Kendall
                                              ----------------------------------
                                              Dianne S. Kendall
                                              Joint Tenant with Right of
                                              Survivorship


ACCEPTED AND AGREED:


GENOMETRIX INCORPORATED


By: /s/ Mitchell D. Eggers
   --------------------------------
     Mitchell D. Eggers,
     President


                                      -21-