Pretend you are a teacher preparing a quiz for the text I will provide. 
            Each quiz question should follow the format below. 
            Ensure that you carefully recheck the questions and answers for accuracy. 
            The output should be a ready-to-use list of dictionaries for the Python eval function:

            [

                    "question": "WRITE THE QUESTION HERE",
                    "options": ["A) OPTION_1", "B) OPTION_2", "C) OPTION_3", "D) OPTION_4"],
                    "answer": INDEX_OF_CORRECT_ANSWER_IN_OPTIONS_LIST,
                    "explanation": "EXPLAIN WHY THE ANSWER IS CORRECT"

            ]

            Text:
            e with a free a-amino group ( at left).
C-terminal residue: residue with a free a- carboxyl group ( at right).
Each peptide has a single free a-amino group and free a-carboxyl gp
Physiologically active peptide:
1- glutathione :(y glutamyl- cysteinyl- glycine) ( GSH)
It is tripeptide acting as strong reducing agent why ? There is
unusual situation to that is bound in the peptide linkage How?
Oxidized glutathion ( G-S-S-G ) may be reduced ( G-SH ) by
glutathione reductase enzyme in the presence of NADPH
G-S-S-G + NADPH 
+ 
2 G-SH + NADP+
The reducing form-ofglutathione is very important, 
since
accumulation of H2ö2 
may decrease 
the life span of the
erythrocyte by increasing 
the rate 
of oxidation 
of hemoglobin
to methemoglobin cause hemolysis 
of RBC
2G-SH + H202( 
toxic) —
G-S-S-G ( not toxic )+ 21-120
2- Bradykinin: arg-pro-pro-gly-phe-ser-pro-phe-arg
3- kallidin: lys- arg-pro-pro-gly-phe-ser-pro-phe-arg
Are smooth muscle hypotensive 
agents, liberated 
from specific
plasma proteins by proteolysis
4- Hormones: 1- Vasopre.s.sion: 
antidiuretic. 
hormon, rise of
blood pressure by constricting 
the peripheral 
blood vessels
Oxytocin: contraction of smooth muscle
Partial hydrolysis of polypeptide chains
Partial or selective hydrolysis of the polypeptide 
chain occur by
proteases enzymes that hydrolysis 
peptide bonds:
1- endopeptidase enzymes:
enzyme
Trypsin
chymotrypsin
pepsin
thermolysin
elastase
Peptide bonds cleaved after
Lys , arg
Phe , trp , tyr
P he , trp , tyr
Leu , ile . Val ( branched chain aa )
gly , ala , 
small aa)
exopeptidase :
carboxy peptidase and aminopeptidase
proteins
Proteins play a central role in cell function 
and cell structure. All proteins
have a high molecular weight ranged 
from few thousand to many millions
Classification of proteins:
1- Simple or complex protein
2- Classification of proteins according to their biological function: catalytic
role, contraction, gene regulation, 
hormonal 
role, protection, regulatory
role, transport, structural role, storage proteins, maintenance of osmotic
pressure and pH
3- Classification of proteins based on their solubility:
Albumin
Globulin
Prolamines
Histones
scteroproteins
Soluble in water
Soluble
Sparingly soluble in water
Insoluble in water
Soluble in water
insoluble in water
•—4-dassifiation according to their shape
A- globular proteins: are characterized by compactly folded and coiled
polypeptide chains e.g. Insulin, 
albumin 
, globulins , many enzymes and
others
B-fibrous proteins: are characterized 
by 
coiled polypeptide chain in 
a spiral
of helix by covalently 
bonds 
or hydrogen 
bonds e.g. keratin , myosin 
,
collagen, fibrin others.
Covalent
• Bonds responsible for protein 
non covalent 
bonds
A- Covalent : peptide bond and disulfide bonds
1- peptide bond: which links 
amino acids 
together in protein. C-N bond 
very rigid
and there is no freedom for rotation about the bond that connect C&N atoms.
This bond has partial double 
bond 
character 
why? because it is sh

            Quiz: