20 amino acids

Question 1

basic structure of an amino acid at neutral pH

Answer 1

NH₃⁺, Cα, H, COO⁻, R

Question 2

asparagine

Answer 2

Asn, N

hydrophilic
non-charged polar

CH₂ - C = O
- NH₂

Question 3

glutamine

Answer 3

Gln, Q

hydrophilic
non-charged polar

CH₂ - CH₂ - C = O
- NH₂

Question 4

serine

Answer 4

Ser, S

hydrophilic
non-charged polar

CH₂ - OH

Question 5

threonine

Answer 5

Thr, T

hydrophilic
non-charged polar

H - C - OH
|
CH₃

Question 6

aspartate/ aspartic acid

Answer 6

Asp, D

hydrophilic
negatively charged, acidic or neutral
pKa 4.4
lots lone pairs for H bonds
salt bridges

CH₂ - COO⁻

Question 7

glutamate/ glutamic acid

Answer 7

Glu, E

hydrophilic
negatively charged (acidic), or neutral
pKa 4.4
lots lone pairs for H bonds
salt bridges

CH₂ - CH₂ - COO⁻

Question 8

lysine

Answer 8

Lys, K

hydrophilic
positively charged (basic)
pKa 10

CH₂ - CH₂ - CH₂ - CH₂ - NH₃⁺

Question 9

histidine

Answer 9

His, H

hydrophilic
positive or neutral
pKa 6

goes round in circle

CH₂ - C - NH - CH =
=C,H - N⁺,H

Question 10

arginine

Answer 10

Arg, R

hydrophilic
positively charged (basic)
pKa 12

CH₂ - CH₂ - CH₂ - NH - C = NH₂⁺
|
NH₂

Question 11

tyrosine

Answer 11

Tyr, Y

hydrophobic/hydrophilic
OH can H bond (hydrophilic)
aromatic ring (hydrophobic)
alternating single/double bond between carbon

CH₂ - ring - OH

Question 12

cysteine

Answer 12

Cys, C

hydrophobic/hydrophilic
SH less polar than OH so can’t H bond but quite reactive

CH₂ - SH

Question 13

alanine

Answer 13

Ala, A

hydrophobic
aliphatic

CH₃

Question 14

aliphatic

Answer 14

straight chains of CH

Question 15

methionine

Answer 15

Met, M

hydrophobic
aliphatic

CH₂ - CH₂ - S - CH₃

Question 16

leucine

Answer 16

Leu, L

hydrophobic
aliphatic

CH₂ - CH - CH₃
- H₃C

Question 17

isoleucine

Answer 17

Ile, I

hydrophobic
aliphatic

H - C - CH₃
       |
     CH₂
       |
     CH₃

Question 18

proline

Answer 18

Pro, P

special one
ring structure
limited flexibility

CH₂ - CH₂ - H₂C - amino group

Question 19

glycine

Answer 19

Gly, G

special one
small
only one without a Cβ

H

Question 20

valine

Answer 20

Val, V

hydrophobic
aliphatic

CH - CH₃
- H₃C

Question 21

phenylalanine

Answer 21

Phe, F

hydrophobic
aromatic

CH₂ - ring

Question 22

tryptophan

Answer 22

Trp, W

hydrophobic
aromatic

CH₂ - C = CH
| |
ring - N - H

Question 23

which AAs are hydrophilic?

Answer 23

lysine
arginine
histidine
aspartate
glutamate
asparagine
glutamine
serine
threonine

Question 24

which AAs are hydrophilic and positively charged?

Answer 24

lysine
arginine
histidine

Question 25

which AAs are hydrophilic and negatively charged?

Answer 25

aspartate | glutamate

Question 26

which AAs are hydrophilic but non-charged and polar?

Answer 26

asparagine glutamine serine threonine

Question 27

which AAs are hydrophobic and hydrophilic?

Answer 27

cysteine | tyrosine

Question 28

which AAs are hydrophobic?

Answer 28

``` alanine valine isoleucine leucine methionine phenylalanine tryptophan ```

Question 29

which AAs are hydrophobic and aliphatic?

Answer 29

``` alanine valine isoleucine leucine methionine ```

Question 30

which AAs are hydrophobic and aromatic?

Answer 30

phenylalanine | tryptophan

Question 31

which AAs have aromatic rings?

Answer 31

tyrosine phenylalanine tryptophan

Question 32

which AAs have ring structures?

Answer 32

histidine tryptophan proline