Amino acids & peptides

Practice Quiz(you will need your amino acid sheet for this quiz)

Question 1

Approximately what mass percent of a body’s dry weight consists of proteins?

a) 5%

b) 25%

c) 50%

d) 72%

Answer: C) sorry, did I forget to mention that in

class?

Question 2

Which functional group, in addition to an amine, do all amino acids contain?

a) an alcohol

b) an amide

c) a carboxylic acid

d) an oxyacid

Answer: C)

Question 3

A peptide bond links

a) an alcohol and a ketone

b) an amide and an aldehyde

c) an amine and a carboxylic acid

d) an amide and a carboxylic acid

Answer: C) H2N CH C

CH3

O

HN CH C

CH2

OH

O

SH

peptide bondamine carboxylic acid

Question 4

What does the term ‘α-amino acid mean?

a) The amino acid attaches to the carbon in the carboxyl group

b) The amino group attaches to the carbon next to the carboxylic acid group

c) The amino acid contains only one carbon atom

d) The amino acid contains only one carboxylic acid group

Answer: b)

H2N CH C

CH

OH

O

OH

CH3

-carbon atom

Question 5

When referring to amino acids, what does the term essential mean? These are acids which

a) are necessary for digestion

b) are necessary for respiration

c) are synthesized in our bodies

d) we must obtain from our diet

Answer: d)

Question 6

Which of the following amino acids is not basic?

a) arginine

b) glycine

c) histidine

d) lysine

Answer: b)

Question 7

Which of the following amino acids is acidic?

a) alanine

b) aspartic

c) glycine

d) valine

Answer: b)

H2N CH C

CH2

OH

O

C

OH

O

Question 8

Which one of the following amino acids contains a double ring structure?

a) phenylalanine

b) proline

c) tryptophan

d) tyrosine

Answer: C)

H2N CH C

CH2

OH

O

HN

Question 9

Which one of the following amino acids contains a benzyl group?

a) glycine

b) isoleucine

c) methionine

d) phenylalanine

Answer: d)

H2N CH C

CH2

OH

O

Question 10

What does the term hydrophobic mean?

a) water reactive

b) water repelling

c) water soluble

d) water proof

Answer: b)

Question 11

Which of the following amino acids is hydrophobic?

a) leucine

b) serine

c) threonine

d) tyrosine

Answer: a)

H2N CH C

CH2

OH

O

CH CH3

CH3

non-polar side chain

Question 12

All but one of the common amino acids contain a –NH2 amino group. Which one contains an –NH- amino acid as part of a ring structure?

a) phenylalanine

b) proline

c) tryptophan

d) tyrosine

Answer: b) HN

C OH

O

Question 13

In how many different ways can the amino acids: ALA, CYS, MET, GLU, SER and TYR connect together to form a polypeptide?

a) Over 5000

b) 720

c) 120

d) 21

Answer: b) 6! = 720

Question 14

The diagram is an example of:

a) An L-amino acid

b) A D-amino acid

c) An achiral-amino acid

d) An amino acid residue

Answer: a)

C

C

R

HH2N

O OH

Question 15

What kind of bonding stabilises helical and β-pleated-sheet secondary protein structure?

a) Vander Waals forces

b) Hydrogen bonding

c) Interactions with neighbouring protein chains

d) Helical and sheet structures are tertiary, not secondary structures

Answer: b)

Who’s your favourite Chemistry teacher?

a) A Kevin

b) A nother

c) A non

d) None of the above

Answer: a) A Kevin

(of course)