Amino, Acids, Peptides, and Protiens

Question 1

Stereochemistry:

alpha-carbons = [–] configuration

Answer 1

L
for all chiral amino acids

Question 2

Stereochemistry

carbohydrates = [–] configuration

Answer 2

D

Question 3

Stereochemistry

all chiral amino acids except [–] have [–] configuration

Answer 3

cysteine
S

Question 4

Stereochemistry

All amino acids expect for [–] are [–]

Answer 4

glycine
chiral

Question 5

pka

Answer 5

the pH at which half the species is deprotonated
[HA] = [A-]

Question 6

Increased pH = amino acid is [–]

Answer 6

fully protonated

Question 7

Decreased pH = amino acid is [–]

Answer 7

fully deprotonated

Question 8

pH = pI = amino acid is [–]

Answer 8

neutral zwitterion
(charges cancel)

Question 9

isoelectric point (pI)

Answer 9

the pH at which an amino acid is in zwitterion form
the charges cancel out to make a neutral molecule

Question 10

pI Equations

For no side chains: pI = ?

Answer 10

1/2(pka of carboxylic group + pka of amine group)

Question 11

pI Equations

For neutral side chain: pI = ?

Answer 11

1/2(pKa of carboxyl group + pKa of amine group)

Question 12

pI Equations:

Basic side chain: pI = ?

Answer 12

1/2(pKa of amine group + pKa of side chain)

Question 13

pI Equations

For acidic side chains: pI = ?

Answer 13

1/2 (pKa of carboxyl group + pKa of side chain)

Question 14

conjugated protein

Answer 14

proteins with covalently attached molecules

Question 15

prosthetic group

Answer 15

the attached molecule in a conjugated protein
can be a metal ion, vitamin, lipid, carbohydrate, or nucleic acid