PROTEINS

Question 1

R: side chain

Answer 1

determines the specific nature of the amino acid

Question 2

NONPOLAR SIDE CHAINS

Answer 2

– no side chain (Gly)
– aliphatic side chain (Ala, Val, Leu, Ile)
– alicyclic side chain: „imino acid” (Pro)
– containing sulfur (Met)
aromatic (Phe, Trp)

Question 3

POLAR SIDE CHAINS

Answer 3

aliphatic
– containing alcoholic hydroxyl group (Ser, Thr)
– containing thiol group (Cys)
– amides (Asn, Gln)
aromatic (containing phenolic hydroxyl Tyr)

Question 4

AMINO ACIDS WITH NET POSITIVE CHARGE at pH7

Answer 4

aliphatic (Arg, Lys)

aromatic (His)

Question 5

What stereoisomer are almost all a.a?

Answer 5

L-stereoisomer

Question 6

What a.a. can absorb UV-Light

Answer 6

tyrosine, tryptophan and phenylalanine,
Tryptophan absorbs 4 times more at 280 nm
phenylalanine very small amount.

Question 7

How does cysteine form cystine?

Answer 7

By being oxidized and forming covalent bond with other cysteine forming disulfide bond

Question 8

A.A haveing positive charge at ph 7?

Answer 8

Lysine, arginine, hisitidine

Question 9

A.A having negatice charge at ph 7?

Answer 9

Aspartate, glutamate

Question 10

Zwitterion

Answer 10

A.A can act either as acid or base and has a net chare of 0

Question 11

What kind of reaction forms peptide bond?

Answer 11

Condensation

Question 12

Chromatography

Answer 12

purification of protein

Question 13

Electrophoresis

Answer 13

seperates proteins according to their size and charge. Smaller travel faster, larger slower.

Question 14

Primary structure

Answer 14

Determine how the protein folds and the function of the protein.

Question 15

proteases

Answer 15

enzyme that hydrolytic cleavage peptide bonds.

Some proteases cleave only peptide bond adjacent to particular a.a

Question 16

Peptide bond

Answer 16

HAs double bond character
cannot rotate
atoms in the bond are coplanar

Question 17

A.a interior

Answer 17

hydrophobic

Question 18

alpha helix

Answer 18

R-gropus protrude outwards
1 helical turn =3,6 a.a residues
Stabalized with h-bonds and wander waals
L-a.a present
Only right handed alpha helix present

Question 19

A.a residues preventing alpha helix

Answer 19

Glu,Lys,Arg

Question 20

Proline in alpha helics

Answer 20

Rarely found since it cant participate in h-bonding

Question 21

H-bonds in beta-sheet

Answer 21

In line in antiparallel

distorted/not in line in parallel

Question 22

Beta turn

Answer 22

4 a.a residues
1.a.a Carvonyl oxygen form h-bond with 4a.a residue amino-group

Gly and Pro often occur in B-turn

Question 23

secondary structure

Answer 23

the spatial arrangement

Question 24

aplha-keratin

Answer 24

alpha helix, cross-linked by disulfide bonds

Question 25

silk fibroin

Answer 25

b-conformation

Question 26

collagen

Answer 26

tripple helix 2ndary structure is left handed 3 a.a/turn

Question 27

Domain

Answer 27

A section of protein structure that perform a particular chemical or physical task, like binding to substrate that gives the overall role of the protein.

Question 28

selenocysteine

Answer 28

The 21 a.a | not product of PTM, insertded during translation

Question 29

what a.a occurs naturally

Answer 29

d-a.a

Question 30

confromation

Answer 30

spatial relationship of every atom in molecule

Question 31

conformation

Answer 31

the geometric relationship between given set of molecules | d- or L- a.a

Question 32

Beta sheet

Answer 32

r-groups opposite to each other Form H-bonds with adjacent segments Tend to have right-handed twist

Question 33

Teritary stucture

Answer 33

3-D shape | how 2nd structual feauters assemble to form domains and how they relate to each other.

Question 34

Quaternary

Answer 34

defines the polypeptide composition of protein H-bomds salt bridges covalent disulfide

Question 35

sulfhhydryl oxidase

Answer 35

catalyzes oxidation of cysteine residue to form disulfide bonds

Question 36

Chaperone

Answer 36

participate in the folding of proteins, prevent aggregation,

Question 37

Prion

Answer 37

Protein conformstion disease | resulting from the deposition od insoluable protein aggregates in neural cells