Exam #1

Question 1

A non-covalent bond is important for the structure and stability of biological molecules. Identify the type of interaction below that is NOT considered a non-covalent bond.

a. Van der Waals interactions
b. Electrostatic interactions
c. Disulfide bonds
d. Hydrogen bonds

Answer 1

c. Disulfide bonds

Question 2

Explain what will happen to the energy released during an interaction when the distance between 2 charged particles doubles while the charge of the particles remains constant (assume K & D are constant).

a. Energy doubles
b. Energy is halved
c. Energy quadruples
d. Energy remains the same

Answer 2

b. Energy is halved

Question 3

Using the following reaction to answer the question:
Ca2+(aq)+ 2 Cl-(aq) –> CaCl2(aq) Delta G = -14 kJ/mol

Increasing the concentration of chloride ion will:

a. shift the equilibrium to the right
b. keep the reaction in equilibrium
c. shift the equilibrium to the left
d. increase the calcium ion concentration

Answer 3

a. shift the equilibrium to the right

Question 4

Using the following reaction to answer the question:
Ca2+(aq)+ 2 Cl-(aq) –> CaCl2(aq) Delta G = -14 kJ/mol

The reaction is…

a. spontaneous
b. non-spontaneous

Answer 4

a. spontaneous

Question 5

A buffer is at a maximum when

a. pH > pKa
b. pH = pKa
c. pH

Answer 5

b. pH = pKa

Question 6

The ratio of carbonic acid: carbonate is 1000:1, respectively, with a typical pKa of 6.3 at 25*C. Calculate the pH and determine if it is in a protonated or deprotonated form.

Answer 6

pH = 3.3

Question 7

Which of the following is not considered a branched chain amino acid?

a. Valine
b. Lysine
c. Leucine
d. Isoleucine

Answer 7

b. Lysine

Question 8

Human ribonuclease, which is a digestive enzyme and Angiogenic, which stimulates blood vessel growth, are structurally very similar but functionally very different in human beings. This is an example of:

a. Ortholog
b. Conservative sequence
c. Metalog
d. Paralog

Answer 8

d. Paralog

Question 9

A protein that consists of covalent and peptide bonds in a linear sequence refers to a:

a. primary structure
b. secondary structure
c. tertiary structure
d. quaternary structure

Answer 9

a. primary structure

Question 10

Which of the following events in the process of protein folding occurs at the slowest rate?

a. rapid formation of secondary structure
b. formation of domains through cooperative aggregation (folding nuclei)
c. formation of assembled domains (molten globule)
d. adjustment of conformation

Answer 10

d. adjustment of conformation

Question 11

How many amino acid residues are there per turn of the alpha helix?

a. 3.4
b. 3.5
c. 3.6
d. 3.7

Answer 11

c. 3.6

Question 12

How many amino acid residues are there per turn of the coiled-coil helix in a fibrous protein molecule?

a. 3.4
b. 3.5
c. 3.6
d. 3.7

Answer 12

b. 3.5

Question 13

Which of the following does not contribute to protein stability?

a. disulfide bonds
b. chaotropic agents
c. formation of oligomers
d. hydrophobic effect

Answer 13

b. chaotropic agents

Question 14

Which of the following is considered to be a chaotropic agent?

a. urea
b. guanidinium fluoride
c. guanidinium chloride
d. hydrochloric acid
e. more than one of the above

Answer 14

e. more than one of the above

Question 15

The E-helix is a series of amino acids in the structure of hemoglobin. Which amino acid residue is the proximal histidine that chelates iron and holds it in place?

a. E7
b. E8
c. F7
d. F8

Answer 15

d. F8

Question 16

How many chelation points may be found in oxygenated hemoglobin?

a. 4
b. 5
c. 6
d. 7

Answer 16

c. 6

Question 17

The iron in hemoglobin may only be in the _____ state to function properly.

a. Fe+
b. Fe2+
c. Fe+
d. none of the above

Answer 17

b. Fe2+

Question 18

Identify the correct type/sub-type of fetal hemoglobin.

a. alpha2, beta2
b. alpha2, delta2
c. alpha2, epsilon2
d. alpha2, gamma2

Answer 18

d. alpha2, gamma2

Question 19

In the “R” state (for hemoglobin), the oxygen-binding sites are free of strain and are capable of binding oxygen with higher affinity than are the sites in the “T” state. (T/F)

a. True
b. False

Answer 19

a. True

Question 20

Identify the correct amino acid substitution and location of the mutation that is present in sickle cell

a. substitution of glutamate for valine on the A6 helix of the beta chain
b. substitution of glutamate for valine on the A6 helix of the alpha chain
c. substitution of glycine for alanine of the A6 helix of the beta chain
d. Substitution of glutamate for valine on the A6 helix of the gamma chain

Answer 20

a. substitution of glutamate for valine on the A6 helix of the beta chain

Question 21

In the energy landscape of protein folding and aggregation, which of the following conditions will favor the formation of amyloid fibrils?

a. Intermolecular interactions in a low energetic state
b. Intramolecular interactions in a low energetic state
c. Intermolecular interactions in a high energetic state
d. Intramolecular interactions in a high energetic state

Answer 21

a. Intermolecular interactions in a low energetic state

Question 22

Normal proteins contain more beta strand structure and little alpha helix structure. (T/F)

a. True
b. False

Answer 22

b. False

Question 23

Which of the following oxidoreducatase enzymes contain iron?

a. oxidases
b. reductases
c. superoxide dismutase
d. all of the above.
e. 2 of the above.

Answer 23

d. all of the above