Quiz Questions

Question 1

Which amino acid has a side chain with a hydroxyl group

Answer 1

Serine

Question 2

Which of the following amino acids have R groups that could participate in hydrogen bonding?

Answer 2

Serine

Question 3

Which type of bond is the strongest in cells?

Answer 3

Covalent

Question 4

Which two amino acids are positively charged at neutral pH?

Answer 4

Lysine and arginine

Question 5

Which of the following could form hydrogen bonds with each other?

Answer 5

N-H and O

O-H and O

Question 6

HEPES is a commonly used buffer and has a pKa of 7.4.

Which of the following is not true about a 100mM solution at pH 7.4.

Answer 6

All of the HEPES molecules are protonated.

Question 7

A hydrophobic molecule is typically…

Answer 7

Incapable of interacting favorably with water.

Question 8

The basic structure of a proteoglycan consists of a core protein attached to a…

Answer 8

Carbohydrate

Question 9

Which of the following is not one of the major lipids found in the plasma membrane of eukaryotic cells?

Answer 9

Phosphatidyl oleic acid

Question 10

Which of the following amino acids would you be likely to find in an alpha helix that crosses a lipid bolster?

Answer 10

Phenylalanine

-Rest are polar or charged

Question 11

The same lipid molecules are found in the inner and outer layers of the lipid bilayer.

Answer 11

False

Question 12

The alpha carbon of amino acids is linked to the amino group of another amino acid to form a peptide bond.

Answer 12

False

-The carboxyl group of one amino acid is linked to the amino group of the other.

Question 13

Ionic interactions are weaker in the presence of water than in the absence of water.

Answer 13

True

Question 14

A solution that has a pH of 9 has a lower concentration of H+ than a solution of pH 4.

Answer 14

True

PH = -log [H+]

*High Ph= low H+

Question 15

Which of the following best describes the defining features of a protein domain?

Answer 15

A sequence of amino acids that folds into a discrete structural and functional unit within a protein.

Question 16

Which of the following is primarily responsible for formation of an alpha helix?

Answer 16

Hydrogen bonding

-The alpha helix is formed by hydrogen by hydrogen bonding between the carbonyl oxygen and the N-H of the peptide bond.

Question 17

Mutations in the nucleic acid sequence of a gene can sometimes direct the substitution of one amino acid for another in the encoded protein.

Which amino acid substitution would be most likely to severely disrupt the normal structure of a protein?

Answer 17

Methionine-> Arginine

Question 18

Which of the following amino acids would you expect to rarely occur in the intrinsically disordered proteins?

Answer 18

Isoleucine

• Intrinsically disordered proteins or protein domains do not fill into a tertiary structure.
• Instead, they exist as disordered unfolded chains of amino acids.
• Disordered proteins have a high proportion of polar + charged amino acids, so they interact with water.
• proteins that fold into tertiary structures have numerous hydrophobic amino acids that become folded into the core of the protein to avoid interacting with water.

Question 19

How many different amino acids are commonly used in making proteins?

Answer 19

20

Question 20

Why are alpha helices and beta sheets common folding patterns in polypeptides?

Answer 20

Amino acid side chains are not directly involved in their formation.

• Both of these folding patterns result from hydrogen bonds that form between N-H groups and C=O from peptide bonds along the polypeptide backbone.
• Because amino acid side chains are not directly involved in forming these hydrogen bonds.
• Alpha helices and beta sheets can be formed by many different amino acid sequences.