Amino Acids

Question 1

Nonpolar R Groups

Answer 1

form hydrophobic interactions, greasy, cluster together

glycine, alanine, proline, leucine, valine, isoleucine, methionine

Question 2

Aromatic R Groups

Answer 2

can be nonpolar or polar/uncharged, can form pi-pi interactions or cation-pi interactions to stack aromatic chains
(phenylalanine, tyrosine, tryptophan)

Question 3

Polar/Uncharged R Groups

Answer 3

soluble in water, hydrophilic, can form H bonds with water

serine, threonine, cysteine, asparagine, glutamine

Question 4

Positively Charged R Groups

Answer 4

very hydrophilic

lysine, arginine, histidine

Question 5

Negatively Charged R Groups

Answer 5

very hydrophilic

aspartate, glutamate

Question 6

Glycine

Answer 6

Nonpolar-Aliphatic
GLY
R Group: H

Question 7

Alanine

Answer 7

Nonpolar-Aliphatic
ALA
R Group: CH3

Question 8

Proline

Answer 8

Nonpolar-Aliphatic
PRO
R Group: CH2-CH2-CH2(bonded to amino group)

Question 9

Leucine

Answer 9

Nonpolar-Aliphatic
LEU
R Group: CH2-CH-(CH3)2

Question 10

Valine

Answer 10

Nonpolar-Aliphatic
VAL
R Group: CH-(CH3)2

Question 11

Isoleucine

Answer 11

Nonpolar-Aliphatic
ILE
R Group: H-C-CH3
                  CH2
                  CH3

Question 12

Methionine

Answer 12

Nonpolar-Aliphatic
MET
R Group: CH2-CH2-S-CH3

Question 13

Phenylalanine

Answer 13

Aromatic
PHE
R Group: CH2-benzene

Question 14

Tyrosine

Answer 14

Aromatic
TYR
R Group: CH2-benzene-OH
pKR = 10.07

Question 15

Tryptophan

Answer 15

Aromatic
TRP
R Group: C=CH2-NH-benzene(back to C)

Question 16

Serine

Answer 16

Polar-Uncharged
SER
R Group: CH2-OH

Question 17

Threonine

Answer 17

Polar-Uncharged
THR
R Group: H-C-OH
CH3

Question 18

Cysteine

Answer 18

Polar-Uncharged
CYS
R Group: CH2-SH
pKR = 8.18
(can form disulfide bonds between two R groups releasing 2H+ and 2e-)

Question 19

Asparagine

Answer 19

Polar-Uncharged
ASN
R Group: CH2
H2N-C=O

Question 20

Glutamine

Answer 20

Polar-Uncharged
GLN
R Group: CH2
                CH2
          H2N-C=O

Question 21

Lysine

Answer 21

Positively Charged
LYS
R Group: CH2
                CH2
                CH2
                CH2
              \+NH3
pKR = 10.53

Question 22

Arginine

Answer 22

Positively Charged
ARG
R Group: CH2
                CH2
                CH2
                 NH
        \+NH2-C-NH2
pKR = 12.48

Question 23

Histidine

Answer 23

Positively Charged
HIS
R Group: CH2-C-NH-CH=N-CH(=back to C)
pKR = 6.00

Question 24

Aspartate

Answer 24

Negatively Charged
ASP
R Group: CH2-COO-
pKR = 3.65

Question 25

Glutamate

Answer 25

Negatively Charged GLU R Group: CH2-CH2-COO- pKR = 4.25