Lesson 3: proteins and enzymes

Question 1

All amino acids are chiral. True or False?

Answer 1

False

Question 2

All amino acids can be synthesised from carbon skeletons that are produced as intermediates in major metabolic pathways. True or False?

Answer 2

False

Question 3

Amino acids are linked by glycosidic bonds. True or False?

Answer 3

False

Question 4

An amino acid sequence is the protein’s

Select one:

a. None of these answers are correct
b. Quaternary structure
c. Primary structure
d. Tertiary structure
e. Secondary structure

Answer 4

c. Primary structure

Question 5

Competitive inhibitors bind to the active site of an enzyme surface. True or False?

Answer 5

True

Question 6

D-isomers of amino acids are extremely rare in nature. True or False?

Answer 6

True

Question 7

Denaturation

Select one:

a. Destroys the active conformation of a protein
b. Is the synthesis of glucose from carbon skeletons
c. Covalently links two amino acids through the formation of peptide bonds
d. Is the pH at which all the molecules have equal positive and negative charges
e. Is the synthesis of amino acids from carbon skeletons

Answer 7

a. Destroys the active conformation of a protein

Question 8

Enzyme activity is often dependent not just on the protein portion of the enzyme, but also on an organic nonprotein group called a(n)

Select one:

a. Isomerase
b. Allosterism
c. Coenzyme
d. Isoenzyme
e. Zymogen

Answer 8

c. Coenzyme

Question 9

Enzymes

Select one:

a. Cannot make a reaction take place that would otherwise not occur without them
b. All of these answers are correct
c. Are unchanged after catalysing a chemical reaction
d. Increase the speed of a reaction by lowering the activation energy
e. Are highly specific

Answer 9

b. All of these answers are correct

Question 10

How many different amino acids are commonly found in proteins in humans?

Select one:

a. 28
b. 8
c. 32
d. 23
e. 20

Answer 10

e. 20

Question 11

The majority of enzymes are

Select one:

a. Alcohols
b. Carbohydrates
c. None of these answers are correct
d. Lipids
e. Proteins

Answer 11

e. Proteins

Question 12

The tertiary structure of a protein can be stabilised by

Select one:

a. Hydrogen bonds
b. Metal ion coordination
c. Hydrophobic interactions
d. All of these answers are correct
e. Salt bridges

Answer 12

d. All of these answers are correct

Question 13

What class of enzyme catalyses oxidation-reduction reactions?

Select one:

a. Lyases
b. Oxidoreductases
c. Transferases
d. Hydrolases
e. Ligases

Answer 13

b. Oxidoreductases

Question 14

Which of the following is a secondary protein structure?

Select one:

a. β-pleated sheet
b. α-helix
c. None of these answers are correct
d. Random coil
e. All of these answers are correct

Answer 14

e. All of these answers are correct

Question 15

Which of the following is NOT a basic amino acid?

Select one:

a. All of these are nonpolar amino acids
b. Arginine
c. Lysine
d. Histidine
e. Glutamic acid

Answer 15

e. Glutamic acid