Biochem- Amino Acids and Residues

Question 1

Which Amino Acids are Non-Polar, Non-Aromatic?

Answer 1

Glycine, Alanine, Valine, Leucine, Isoleucine , Methionine, Proline
(GAVLIMP)

Question 2

Which Amino Acids are Non-Polar, Aromatic?

Answer 2

Tryptophan, Phenylalanine, Tyrosine
(WFY)
( Tyrosine= polar, Tryptophan and Phenylalanine= Non-polar)

Question 3

Which Amino Acids are Polar ?

Answer 3

Serine, Threonine, Asparagine, Glutamine, Cysteine

S,T,N,Q,C

Question 4

Negative Charged Side chains ( acidic )

Answer 4

Aspartate (aspartic acid), Glutamate ( glutamic acid)

D,E) ( DEA - acidic

Question 5

Positive Charged Side chains (basic)

Answer 5

Arginine, Lysine, Histidine

KRH

Question 6

Glycine side chain and abbreviations (1, 3)

Answer 6

2 H’s on Side chain position, Gly, G

Question 7

Alanine side chain and abbreviations

Answer 7

CH3 group , Ala , A

Question 8

Valine side chain and abbreviations

Answer 8

Isopropyl group ( CH, CH3x2), Val, V

Question 9

Where do the side chains come off of ?

Answer 9

the central carbon, between the amine and carboxyl group

Question 10

Leucine side chain and abbreviations

Answer 10

isobutyl side chain ( CH,CH2, CH3x2), Leu, L

Question 11

Isoleucine side chain and abbreviations

Answer 11

isomer of leucine, intead of isobutyl- has sec-butyl side chain, Ile, I

Question 12

Methionine side chain and abbreviations

Answer 12

2 Ch2- Sulfur- CH3, Met, M

Question 13

Proline side chain and abbreviations

Answer 13

3 C chain that loops around and connects back to parent amino, Pro, P

Question 14

Tryptophan side chain and abbreviations

Answer 14

only AA with 2 fused rings, one contains another Nitrogen group, Trp , W

Question 15

Phenylalanine side chain and abbreviations

Answer 15

1 attached benzene ring, Phe, F

Question 16

Tyrosine side chain and abbreviations, Polarity/ Hydrophobicity note

Answer 16

Benzyl group ( benzene ring with OH), Tyr, Y
Relatively Polar, But still Hydrophobic

Question 17

Serine side chain and abbreviations

Answer 17

CH2- OH, Ser, S

Question 18

Threonine side chain and abbreviations

Answer 18

3 different groups- CH, CH3, OH, Thr , T

Question 19

Asparagine side chain and abbreviations

Answer 19

Amide ( CH2-C=O- NH2), Asn, N

Question 20

Glutamine side chain and abbreviations

Answer 20

extra CH2 from asparagine , Amide ( CH2x2- C=O-NH2), Gln, Q

Question 21

Cysteine side chain and abbreviations, polarity/ hydrophobicity

Answer 21

contains only thiol group ( CH2-SH), Cys, C, slightly polar but still hydrophobic

Question 22

Aspartate side chain and abbreviations, and protonated form

Answer 22

CH2-C=O-O^-1, (anion form), Asp, D

protonated form: CH2-C=O-OH ->aspartic acid

Question 23

glutamate side chain and abbreviations, and protonated form

Answer 23

CH2-CH2-C=O-O^-1 ( anion form), Glu, E

protonated form: CH2-CH2- C=O- OH -> glutamic acid

Question 24

Arginine side chain and abbreviations

Answer 24

long nitrogen filled sidechain with a double bonded N (CH2x3- NH-C=NH- H2N), Arg, R

Question 25

Lysine side chain and abbreviations

Answer 25

long C chain (CH2x4), ending with H2N, Lys, K

Question 26

Histidine side chain and abbreviations

Answer 26

imidazole side chain ( heterocyclic, with an N=C and an N-H group within the ring), His , H

Question 27

are the + charged side chains acidic or basic?

Answer 27

basic

Question 28

are the - charged side chains acidic or basic ?

Answer 28

acidic

Question 29

At low pH, what protonated form do the amino acids exist in ( + vs - charge)? How do acidic amino acids behave?

Answer 29

fully protonated ( +charge), acidic AA’s have a pI well below 6

Question 30

At high pH, what protonated form do the amino acids exist in ( + vs - charge)? How do basic amino acids behave?

Answer 30

fully deprotonated ( - charge), basic AA’s have a pI well above 6

Question 31

At pH near pI, what form does the amino acid exist in and how do uncharged amino acids behave?

Answer 31

AA is neutral= zwitterion, AA with no charge have a pI around 6

Question 32

What is an amino acids pI? How does it affect AA solubility?

Answer 32

Isoelectric point, point at which the molecule is neutral, Amino acids are least soluble at pI

Question 33

General formula for pI

Answer 33

pI= (pKa1 + pKa2)/2

Question 34

What amino acid is the only non-chiral AA?

Answer 34

glycine

Question 35

What is the stereochemsitry and chirality of most amino acids?

Answer 35

L chirality, S stereoisomer configuration

Question 36

which amino acid doesn’t have the usual stereochemistry?

Answer 36

cysteine: L-chirality , R configuration