Intro to Amino Acids and Proteins

Question 1

What is the primary structure of proteins?

Answer 1

The sequence of amino acids (chain)

Question 2

What is the center carbon of an amino acid called?

Answer 2

Alpha carbon

Question 3

Carbons that are bonded to 4 different substituent groups are called what?

Answer 3

Chiral or assymetric

Question 4

The alpha carbon is chiral in all amino acids except which one?

Answer 4

Glycine

Question 5

Where are the D-amino acids found?

Answer 5

Usually in the cell walls of bacteria - they are an exception to the rule

Question 6

What are the naturally occurring amino acids?

Answer 6

L-amino acids

Question 7

What is a Zwitterion?

Answer 7

Has no overall charge, but regions with positive and negative charges

Question 8

What are the 9 essential amino acids?

Answer 8

Histidine
Isoleucine
Leucine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
Lysine

Question 9

What are the 7 conditionally non-essential amino acids?

Answer 9

Arginine
Asparagine
Glutamine
Glycine
Proline
Serine
Tyrosine

Question 10

What are the 4 non-essential amino acids?

Answer 10

Alanine
Aspartate
Cysteine
Glutamate

Question 11

When are conditionally non-essential amino acids required?

Answer 11

• Certain stages of growth

- Needed by some people who cannot synthesize them due to a genetic or medical condition

Question 12

How many nonpolar, aliphatic amino acids are there?

Answer 12

7

Question 13

How many polar, uncharged amino acids are there?

Answer 13

5

Question 14

How many aromatic amino acids are there?

Answer 14

3

Question 15

How many positively charged (basic) amino acids are there?

Answer 15

3

Question 16

How many negatively charged (acidic) amino acids are there?

Answer 16

2

Question 17

What are the 7 nonpolar, aliphatic amino acids?

Answer 17

Glycine (Gly, G)
Alanine (Ala, A)
Proline (Pro, P)
Leucine (leu, L)
Isoleucine (Ile, I)
Valine (Val, V)
Methionine (Met, M)

Question 18

For which type of protein interactions are the nonpolar amino acids important?

Answer 18

Hydrophobic protein interactions

Question 19

Which nonpolar amino acid allows for structural flexibility, due to its small size?

Answer 19

Glycine (Gly, G)

Question 20

Which nonpolar amino acid reduces flexibility because of its secondary amino group ring structure?

Answer 20

Proline (Pro, P)

Question 21

Why is methionine important?

Answer 21

It is important in methyl group transfers

Question 22

Is proline flexible or rigid?

Answer 22

Rigid

Question 23

What are the 5 polar, uncharged amino acids?

Answer 23

Serine (Ser, S)
Threonine (Thr, T)
Cysteine (Cys, C)
Asparagine (Asn, N)
Glutamine (Gln, Q)

Question 24

What makes serine and threonine polar?

Answer 24

The OH groups

Question 25

What makes cysteine polar?

Answer 25

The sulfur atom

Question 26

What makes asparagine and glutamine polar?

Answer 26

The amide groups

Question 27

The polar, uncharged amino acids can form what bonds with water, making them hydrophilic?

Answer 27

Hydrogen bonds

Question 28

What are the 3 important functions of the polar, uncharged amino acids?

Answer 28

1. OH of serine and threonine are sites for covalent modifications (ex. physphorylation) 2. Cysteine forms covalent disulfide bonds that are important form protein folding 3. Asparagine and glutamine are important N donors/carriers

Question 29

What does oxidizing 2 amino acids allow to bond?

Answer 29

It allows bonding between the 2 sulfur atoms

Question 30

What are the 3 aromatic amino acids?

Answer 30

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

Question 31

Are aromatic amino acids relatively polar or nonpolar?

Answer 31

Relatively nonpolar - they can participate in hydrophobic interactions

Question 32

At what wavelength do aromatic amino acids absorb light?

Answer 32

280 nm - can be used for protein quantitation

Question 33

What are the 3 positively charged (basic) amino acids?

Answer 33

Histidine (His, H) Arginine (Arg, R) Lysine (Lys, K)

Question 34

Why are the positively charged amino acids positively charged at pH 7?

Answer 34

Because of their amino group (NH3+)

Question 35

What are the 2 negatively charged (acidic) amino acids?

Answer 35

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

Question 36

Why are the negatively charged amino acids negatively charged at pH 7?

Answer 36

Their carboxyl group (COO-) side chains

Question 37

What is desmosine made of?

Answer 37

4 lysine residues

Question 38

What does desmosine do?

Answer 38

Contributes to the stretchiness of elastin

Question 39

Scurvy is caused by what?

Answer 39

A lack of vitamin C

Question 40

Vitamin C is a cofactor for what?

Answer 40

Prolyl hydroxylase

Question 41

What does prolyl hydroxylase do?

Answer 41

Catalyzes the formation of hydroxyproline, which stabilized collagen

Question 42

Which non-standard amino acid is found in myosin?

Answer 42

N-methyllysine

Question 43

Which non-standard amino acid is found in prothrombin?

Answer 43

gamma-carboxyglutamate