Amino Acids

Question 1

What amino acid (aa) doesn’t have chirality

Answer 1

Glycine

Question 2

Amino acids exist in what enantiomers

Answer 2

L and D

Question 3

What type of enantiomer is found in protein

Answer 3

L

Question 4

Formation of stable repeating sequences in proteins require their constituent amino acid to be what

Answer 4

To be of one stereochemical series

Question 5

Why are cells able to synthesise the L isomer of amino acids

Answer 5

Active site of enzymes is asymmetric, causing the reactions they catalyse to be stereospecific

Question 6

Name the 5 groups within the 20 amino acids

Answer 6

Nonpolar aliphatic aa 
Polar uncharged aa
Positively charged basic aa
Negatively charged acidic aa
Aromatic amino aa

Question 7

Name the 7 aa’s that are non-polar aliphatic

Answer 7

Glycine G
Alanine A
Valine V
Leucine L
Isoleucine I
Proline P
Methionine M

Question 8

Proline has what in it and is therefore what

Answer 8

Has cyclic amino acids and so difficult to fold so produces kink in polypeptide chain

Question 9

What aa has the simplest structure

Answer 9

Glycine

Question 10

Name the 5 polar, uncharged amino acids

Answer 10

Serine S
Threonine T
Cysteine C
Asparagine N
Glutamine Q

Question 11

R groups of polar uncharged aa’s are what

Answer 11

More soluble and hydrophilic compared to other aa’s

Question 12

Functional groups in polar uncharged aa’s can form what

Answer 12

Hydrogen bonds

Question 13

Polarity in serine and threonine is due to what functional group?

Answer 13

Hydroxyl groups - OH

Alcohol amino acids

Question 14

Polarity in cysteine is due to what functional group?

Answer 14

Sulfhydryl group

Question 15

Polarity in asparagine and glutamine is due to what functional group?

Answer 15

Amide group

Question 16

Side chain on cysteine can ionise at what pH

Answer 16

High pH

Question 17

Name of the diameric aa formed covalently by cysteine

Answer 17

Cysteine

Question 18

What bond does cystine have

Answer 18

Disulfide

Question 19

Disulfide linked residues are what

Answer 19

Strongly hydrophobic and nonpolar

Question 20

Why does disulfide bonds play a special role in structures

Answer 20

Forms covalent links between proteins or 2 different polypeptide chains

Question 21

Name the 3 positively charged basic aa’s

Answer 21

Lysine K
Arginine R
Histidine H

Question 22

The R groups of Lysine and Arginine carry what 1) charge 2) are what at pH

Answer 22

Positive charges and are strongly polar at pH7

Question 23

Lysine and arginine are hydrophilic or hydrophobic

Answer 23

Hydrophilic

Question 24

Lysine and Arginine are found where on proteins

Answer 24

Exterior because they are hydrophilic

Question 25

Lysine has what on its side chain

Answer 25

Secondary amino group

Question 26

Arginine has what R group

Answer 26

Positively charged guanindo group

Question 27

Histidine has what group

Answer 27

Imidazole

Question 28

Histidine is the only aa with what

Answer 28

An ionisable side chain with a pKa near neutrality

Question 29

In many enzyme catalysed reactions, what aa facilitates the reaction by serving as a proton donor/acceptor

Answer 29

Histidine

Question 30

Name 2 negatively charged acidic aa's

Answer 30

Aspartate D | Glutamate E

Question 31

R groups of aspartate and glutamate carry what net charge at pH 7

Answer 31

Negative

Question 32

Aspartate and glutamate are hydrophilic or hydrophobic

Answer 32

Hydrophilic

Question 33

Aspartate and glutamate have a 2nd what functional group

Answer 33

Carboxyl is

Question 34

Name 3 Aromatic aa's

Answer 34

Phenylalanine F Tyrosine Y Tryptophan W

Question 35

R groups in the aromatic aa's are polar or nonpolar?

Answer 35

Nonpolar

Question 36

Aromatic aa's participate in hydrophobic or hydrophilic interactions

Answer 36

Hydrophobic

Question 37

Tyrosine hydroxyl group forms what

Answer 37

Hydrogen bonds

Question 38

Why are Tyrosine and tryptophan more polar than phenylalanine

Answer 38

Tyrosine hydroxyl group and tryptophan indole ring

Question 39

Which amino acids absorb UV light

Answer 39

Tyrosine, tryptophan and phenylalanine

Question 40

All amino acids have what functional groups

Answer 40

A carboxyl group - COO- An amino group - H3N+ One hydrogen An R group