Amino Acids

Question 1

CH2OH

Answer 1

Serine, hydroxyl group can donate/accept H bonds

Question 2

H-C-OH
|
CH3

Answer 2

Threonine, hydroxyl group

Question 3

CH2
|
SH

Answer 3

Cysteine, sulfhydryl group can lose H and become S-

Question 4

CH2
|
C
/
H2N O

Answer 4

Asparagine, carboxamide group, patial - on O, partial + on N, never ionizes

Question 5

CH2
|
CH2
|
C
/
H2N O

Answer 5

Glutamine, similar to asparagine but longer

Question 6

CH2
|
CH2
|
CH2
|
CH2
|
NH3+

Answer 6

Lysine, amine is basic (pKa ` 10)

Question 7

CH2
|
CH2
|
CH2
|
NH
|
C = NH2+
|
NH2

Answer 7

Arginine, more basic than lysine

Question 8

CH2
|
C-NH
|| \
|| CH
|| /
CH-N

Answer 8

Histidine, imidazole ring (5 membered ring), N becomes protonated and gets + charge, pKa ~7

Question 9

CH2
|
COO-

Answer 9

Aspartate, looks like deaminated asparagine, pKa ~4, can ionize

Question 10

CH2
|
CH2
|
COO-

Answer 10

Glutamate, looks like deaminated glutamine, can ionize

Question 11

CH2
|
(benzene ring)

Answer 11

Phenylalanine, entirely hydrophobic

Question 12

CH2
|
(benzene ring)
|
OH

Answer 12

Tyrosine, not entirely hydrophobic bc hydroxyl group which can ionize, pKa ~ 10

Question 13

CH2
|
C=CH
| \
| NH
| /
(benzene ring)

Answer 13

Tryptophan, only heterocyclic aromatic group w 5 membered ring fused to 6 membered ring, NH group can donate H-bond, unable to ionize bc of fused ring

Question 14

H

Answer 14

Glycine, not chiral

Question 15

CH3

Answer 15

Alanine

Question 16

/ \
H2N+ CH2
| |
H2C - CH2

Answer 16

Proline, 3 hydrocarbon aliphatic side chain that comes back & covalently bonds to amino group

Question 17

CH2
|
CH
/ \
CH3 CH3

Answer 17

Leucine, longer than valine

Question 18

CH
/ \
CH3 CH3

Answer 18

Valine, V-shaped

Question 19

H - C - CH3
|
CH2
|
CH3

Answer 19

Isoleucine, isomer of leucine

Question 20

CH2
|
CH2
|
S
|
CH3

Answer 20

Methionine, methylated thyl group (thyl = sulfur)