BIOCHEM 4 - AMINO ACIDS

Question 1

Essential Amino acids

Answer 1

L, I, V, H, K, M, F, T, W

Question 2

Non-essential amino acids

Answer 2

A, R, N, D, C, E, Q, G, P, S, Y

Question 3

aa (obtained from nutrition)

Answer 3

Essential Amino acids

Question 4

aa (synthesized by the body)

Answer 4

Non-essential amino acids

Question 5

properties of AA (4)

Answer 5

Amphoteric
dipolar
optically active
tetrahedral structure

Question 6

– reference to determine if the

amino acid has L- or D-configuration

Answer 6

α-amino group

Question 7

All amino acids in naturally occurring proteins are

Answer 7

L-isomers

Question 8

◦ derived from glutamate; neurotransmitters (has something to do with the brain)

Answer 8

GABA

Question 9

GABA is derived from

Answer 9

glutamate

Question 10

◦ derived from tryptophan; important in sleep

Answer 10

Serotonine

Question 11

serotonine derived from

Answer 11

derived from tryptophan

Question 12

3. Thyroxine

Answer 12

derived from tyrosine

Question 13

indole acetic acid

Answer 13

4. Dopamine –

Question 14

– side chain is a primary alcohol; looks like Ala with -OH

Answer 14

Serine

Question 15

side chain is a secondary alcohol;

Answer 15

◦ Threonine

Question 16

has two chirality centers

Answer 16

threonine and isoleucine

Question 17

contains a thiol group; important in disulfide linkages; weak acid; can form H-bonds

Answer 17

◦ Cysteine

Question 18

• ionized cysteine is —–, while the protonated form is much ——–than serine.

Answer 18

polar

less polar

Question 19

also has the ability to form covalent bonds called disulfide bonds between cysteine side chains.

Answer 19

Cysteine

Question 20

– side chain is phenolic –OH; borderline case

Answer 20

Tyrosine

Question 21

not very soluble in water, but contains a polar hydroxyl group in the para position of the phenyl ring

Answer 21

Tyrosine

Question 22

amide groups do not become charged at biologically relevant pH values (i.e. pH 2-12), true or false

Answer 22

TRUE

Question 23

simplest amino acid

Answer 23

GLYCINE

Question 24

does not really have a polar or non-polar character

Answer 24

GLYCINE

Question 25

- has much less steric hindrance than the other AAs;

Answer 25

GLYCINE

Question 26

No chiral center/achiral

Answer 26

GLYCINE

Question 27

no asymmetric carbon

Answer 27

GLYCINE

Question 28

– side chain is isopropyl

Answer 28

Valine

Question 29

side chain is isobutyl

Answer 29

Leucine

Question 30

side chain is sec-butyl; has 2 chiral carbons

Answer 30

Isoleucine –

Question 31

more hydrophobic than cysteine (S-containing amino acids)

Answer 31

Methionine

Question 32

start amino acid

Answer 32

Methionine

Question 33

having thioether

Answer 33

Methionine

Question 34

– cyclic but not aromatic; 2ndary α-amino group or α-imino acid - has a conformationally restricted structure

Answer 34

Proline

Question 35

behaves more like a polar amino acid since ----- has a fairly high tendency to appear on the solvent-exposed surface of proteins

Answer 35

proline

Question 36

– has an indole ring; borderline hydrophobic/polar

Answer 36

Tryptophan

Question 37

what AA has the proton attached to the indole nitrogen can act as a hydrogen bond donor to water or other hydrogen bond acceptors

Answer 37

Tryptophan

Question 38

majority of the large tryptophan side-chain is polar or not?.

Answer 38

non-polar

Question 39

acidic form of asparagines; β-carboxyl group

Answer 39

Aspartate-

Question 40

acidic form of glutamine; γ-carboxyl group

Answer 40

Glutamate–

Question 41

– has a primary amino group | protonated at pH 7.0

Answer 41

◦ Lysine

Question 42

contains ε-amino group

Answer 42

◦ Lysine

Question 43

diamino acid

Answer 43

◦ Lysine

Question 44

– most basic amino acid

Answer 44

Arginine

Question 45

contains guanido group

Answer 45

Arginine

Question 46

guanidinium ion always protonated

Answer 46

Arginine

Question 47

heterocyclic ring side chain; not aromatic

Answer 47

Histidine

Question 48

contains imidazole

Answer 48

Histidine

Question 49

only amino acid that functions as buffer in physiological range

Answer 49

Histidine

Question 50

all are very hydrophobic absorbs UV at 280 nm aromatic amino acids

Answer 50

Tyrosine, Tyr (Y) Tryptophan, Trp (W) Phenylalanine, Phe (F)

Question 51

contain carboxyl groups (weaker than α-carboxyl group) | negatively charged at physiological pH;

Answer 51

Aspartate, Asp (D) | Glutamate, Glu (E)

Question 52

present as conjugate bases | carboxyl groups function as nucleophiles in some enzymatic reactions

Answer 52

Aspartate, Asp (D) | Glutamate, Glu (E)

Question 53

classified as β-branched have greater steric hindrance exhibit more restricted conformational flexibility

Answer 53

Valine, Val (V) Isoleucine, Ile (I) Threonine, Thr (T)

Question 54

18 of the 19 L-amino acids have --- configuration

Answer 54

S

Question 55

cysteine has -- configuration

Answer 55

R

Question 56

is neither very | hydrophobic nor very hydrophilic.

Answer 56

Proline

Question 57

As the pH increases, the charge on the molecule becomes

Answer 57

more negative,

Question 58

as the pH decreases, | the charge on the molecule becomes

Answer 58

more positive.

Question 59

zero net charge state is known as the

Answer 59

zwitterionic state

Question 60

is capable of both accepting | and donating protons

Answer 60

zwitterion

Question 61

characteristic of free amino acids with non-ionizable side chains near pH 7.0

Answer 61

zwitterion

Question 62

At pH >> pKa, the ionizable group will be . | -

Answer 62

deprotonated

Question 63

At pH >> pKa, For carboxylic acids, the group will be ____ charged;

Answer 63

negatively

Question 64

At pH >> pKa, amines will be ____

Answer 64

neutral

Question 65

At pH << pKa, the ionizable group will be _______

Answer 65

protonated.

Question 66

At pH << pKa, For carboxylic acids, the group will be __

Answer 66

neutral

Question 67

At pH << pKa, amines will be _____

Answer 67

positively charged

Question 68

has a chemically basic side chain but acidic pKa

Answer 68

histidine

Question 69

pKa values of amino groups of common AA

Answer 69

occur in a range from pH 9 to pH 11

Question 70

pKa values of carboxyl groups of common AA

Answer 70

ph 2