Lecture 1 - Amino acids

Question 1

Proteins are polymers of

Answer 1

amino acids

Question 2

A protein’s amino acid sequence is known as its

Answer 2

primary structure

Question 3

The primary structure determines the amino acids

Answer 3

3-D structure (conformation)

Question 4

A protein’s structure determines the _________ of that protein.

Answer 4

function

Question 5

Amino acids join via

Answer 5

peptide bonds

Question 6

The ________ of amino acids account for the large variety in protein function.

Answer 6

functional groups

Question 7

Amino acids contain a central _______ _______ atom (except proline).

Answer 7

tetrahedral carbon

Question 8

For 19 of the 20 amino acids, the alpha-amino group is

Answer 8

primary

Question 9

The alpha-carbon is a stereorcenter for every amino acid except

Answer 9

glycine

Question 10

Which amino acids predominate in nature, L or R?

Answer 10

L

Question 11

Five groups of amino acid side chains

Answer 11

1. Non-polar aliphatic
2. Aromatic
3. Polar uncharged
4. Positively charged
5. Negatively charged

Question 12

Aliphatic amino acids (7)

Answer 12

Glycine
Alanine
Valine
Leucine
Isoleucine
Proline
Methionine

Question 13

Aromatic amino acids (3)

Answer 13

Phenylalanine
Tyrosine
Tryptophan

Question 14

Polar, uncharged amino acids (5)

Answer 14

Serine
Threonine
Cysteine
Glutamine
Asparagine

Question 15

Positively charged amino acids (3)

Answer 15

Lysine
Arginine
Histidine

Question 16

Negatively charged amino acids

Answer 16

Aspartate
Glutamate

Question 17

Cysteine residues react with each other to form

Answer 17

disulfide bonds

Question 18

Cytoplasm is a reducing environment, preventing the formation of

Answer 18

disulfide bonds

Question 19

Which amino acid can bind and release protons near physiological pH?

Answer 19

Histidine

Question 20

Amino acids are weak ________ acids

Answer 20

polyprotic

Question 21

The degree of dissociation in amino acids depends on the pH of the

Answer 21

medium it is in

Question 22

Alpha carboxyl group pKa

Answer 22

2

Question 23

Alpha amino group pKa

Answer 23

9

Question 24

The isoelectric point, pI, is

Answer 24

the pH of an amino acid at which the molecule has an average net charge of zero.

Question 25

For simple amino acids, the pI is

Answer 25

the average of the pKa’s of the carboxyl and ammonium groups.

Question 26

For amino acids with additional acidic or basic groups, the pI is

Answer 26

the average of the pKa’s of the two most similar acids.

Question 27

pKa tells us how acidic a

Answer 27

hydrogen atom in a molecule is

Question 28

pH tells us how acidic a

Answer 28

solution is

Question 29

At physiological pH, the _______ group is completely dissociated.

Answer 29

alpha carboxyl