Amino Acids and Protein Structure

Question 1

Components of AA

Answer 1

C, carboxylic acid, amino group, H

Question 2

Nonpolar Amino Acids

Answer 2

in interior of soluble proteins and membrane associated proteins to interact with nonpolar fatty acids
hydrophobic clumping contributes to stability of structure

Question 3

Maple Syrup Urine Disease

Answer 3

defective breakdown of branched chain aa (Isoleucine, leucine, valine)
Neurotoxicity can lead to mental retardation
Treated with diet low in those aa

Question 4

Phenylalanine

Answer 4

Nonpolar
converted to tyrosine during catabolism
defect in this causes PKU
neurotoxicity causes retardation
treatment is diet low in Phe

Question 5

Tryptophan

Answer 5

Nonpolar

precursor for serotonin, which is a neurotransmitter for pain, sleep, appetite, temp, bp, mood

Question 6

Glycine

Answer 6

Nonpolar

Collagen = Gly-X-Y

Question 7

Oseogenesis imperfecta

Answer 7

normal collagen structure disrupted by switching glycine for another aa
can cause death in utero or multiple fractures at birth

Question 8

Proline

Answer 8

Nonpolar
rigid structure around A carbon
special structural roles in some proteins, and can interfere with formation of some structures

Question 9

Methionine

Answer 9

Nonpolar

Methyl group donor in methylation reactions

Question 10

Polar Amino Acids

Answer 10

R-Groups participate in H or ionic bonds- interact with each other, aqueous environment, other proteins

Question 11

Acidic Amino Acids

Answer 11

Aspartate and Glutamate

each gives -1 charge in polypeptide

Question 12

Basic Amino Acids

Answer 12

Lysine and Arginine

each gives +1 charge to polypeptide chain

Question 13

Histidine

Answer 13

basic aa, but does not count toward charge of polypeptide
can affect pKa of weak acids or bases
carries partial positive charge in hemoglobin

Question 14

Phosphorylation of Hydroxyl Groups

Answer 14

on Serine, Threonine, Tyrosine (polar uncharged)

contributes to activity of enzymes or in signal transduction

Question 15

Disulfide Bonds

Answer 15

2 Cys residues (Polar Uncharged)

contribute to strength of structure

Question 16

Asparagine

Answer 16

Polar Uncharged

amide group can form N linkage in glycosidic bonds

Question 17

Serine and Threonine

Answer 17

Hydroxyl group can form O linkage in glycosidic bonds

Question 18

Glycoprotein Functions

Answer 18

cell surface recognition
cell surface antigenicity
extracellular matrix
Mucins (glycoproteins that protect digestive tract)

Question 19

Histones

Answer 19

(-) DNA binds to (+) histones with Lys and Arg

Question 20

Histidine

Answer 20

precursor for histamine

Question 21

Histamine

Answer 21

messenger that mediates gastric acid secretion and allergic and inflammatory response

Question 22

Tyrosine

Answer 22

precursor for catecholamines (dopamine, epinephrine norepinephrine)

Question 23

Defects of protein folding

Answer 23

genetic mutations
age related cellular inefficiencies
environmental/ nutritional abnormalities
ischemia/ reperfusion

Question 24

Peptide Bond

Answer 24

between carboxyl group and amino group

polar nature makes A Helix and B Sheets possible

Question 25

Primary Structure of Proteins

Answer 25

peptide bonds join aa; is polar; is rigid

Question 26

A Helix

Answer 26

R groups on outside and are close to each other

H bonds between O and amide H

Question 27

B Sheet

Answer 27

H bonds between sections of peptide that fold back on each other (anti/ parallel)
h bonds perpendicular to peptide bonds

Question 28

Hydrophobic Interactions

Answer 28

2 nonpolars

Question 29

Hydrogen Bonds

Answer 29

2 partially charged polars

Question 30

Ionic Bonds

Answer 30

Full (+) Charge and Full (-) Charge

Question 31

Disulfide Bonds

detailed

Answer 31

created by oxidation rxn b/t 2 Cys in polypep chain

Covalent bond that adds stability

Question 32

Hydrophobic Interactions

detailed

Answer 32

in core of globular proteins away from water

contribute to stability of tertiary structure

Question 33

Quaternary Structure

Answer 33

1+ polypeptide chain

formed by hydrophobic, H, ionic bonding