AAMC C/P Section Bank-done

Question 1

Thin lens formula

Answer 1

1/o + 1/i = 1/f

o=object
i=image
f=focal length

Question 2

kinetic energy in the photoelectric effect

Answer 2

hf-W

Question 3

Which alcohol will most likely undergo substitution by an SN1 mechanism in acidic conditions?

Answer 3

Tertiary

this alcohol produces the most stable carbocation (tertiary) and consequently will most easily lose a water molecule upon protonation of the hydroxyl group in acidic media

Question 4

Energy is

Answer 4

power/time

Question 5

fingerprinting as proteolytic cleavage is a ____ reaction

Answer 5

hydrolysis

Question 6

Ohm’s Law

Answer 6

R=V/I

Question 7

Thermodynamic vs kinetic control

Answer 7

Thermodynamic products are favored at high temperatures, have lower energy, and are more stable. However, their formation occurs more slowly because greater activation energy is required. Kinetic products, on the other hand, are favored at a lower temperature, have higher energy, and are less stable.

So based on this, I reasoned that because compound 2 formed new liposomes with a size that was EXPECTED it is thermodynamic/favorable and compound 1 did not change with the conditions so it was the less favorable & kinetic.

Question 8

free energy of the reaction ΔG′°

Answer 8

ΔG′° = –RTln(Keq)

The free energy of the reaction ΔG′° is related to the equilibrium constant Keq = [ADP][Pi]/[ATP] as ΔG′° = –RTln(Keq). Applying [Pi] = 1 and using the expression for Keq gives ΔG′° = –RTln([ADP]/[ATP]), so that [ADP]/[ATP] = e(30/2.5) = e12.

Question 9

What is the electronic configuration of the Co(II) center found in vitamin B12?

Answer 9

[Ar] 3d7

Co(II) is a dication and is formed from the atomic element by the loss of two 4s electrons. As a consequence, only seven 3d electrons remain in the valence shell.

Question 10

The ATP-dependent phosphorylation of a protein target is catalyzed by which class of enzyme?

Answer 10

Transferase
The answer is B because kinases catalyze the transfer phosphate groups from ATP to target proteins and are classified as transferases. The item stem describes a kinase.

Question 11

What was the most likely purpose of adding bovine serum albumin to the kinetics experiments in the passage? Bovine serum albumin:

Answer 11

prevents the esterase from adhering to the walls of the vessel

The answer to this question is B since the passage specifically states that albumin is a protein that mobilizes proteins and lipids in serum. In the context of a kinetics experiment it is perfectly logical to assume that albumin is added to maintain homogeneity and prevent the enzyme from adhering to walls and other surfaces which would inhibit its activity.

Question 12

catalytic efficiency

Answer 12

kcat/km

Question 13

bond that links monosaccharides together in an oligosaccharide is a special type of acetal linkage known as a _____ bond

Answer 13

glycoside

Question 14

anion-exchange column

Answer 14

In an anion exchange column, the packing is positively charged and therefore retains negatively charged molecules by coulombic interaction.

By increasing the salt concentration (generally by using a linear salt gradient) the molecules with the weakest ionic interactions start to elute from the column first.

Question 15

If there is a single band at 35 kDa on a reducing SDS-PAGE, what size the the tetramer?

Answer 15

140 kDa

Question 16

In an SDS-PAGE under non-reducing conditions, disulfide-linked groups will not be _____.

Answer 16

reduced

Question 17

In an SDS-PAGE under non-reducing conditions, monomers, homotrimers, etc, will run as ____.

Answer 17

monomers

Question 18

A protein contains four disulfide bonds. In order to break these bonds researchers added a minimum of:

Answer 18

4 moles of NADH for each mole of protein

The answer is B because each mole of NADH can reduce a mole of disulfide bonds. Since the protein has four disulfide bonds, four moles of NADH are needed.

Question 19

A protein with which properties will most likely have the largest negative net charge at pH 7?

Answer 19

a protein that binds to an anion-exchange column at ph 7 and required high NaCl concentration for elution

Question 20

On a thermal denaturation graph, where is the melting point

Answer 20

Tm is the temperature at which 50% of the molecules are denatured or the fraction folded is 0.5.

Question 21

Galactose

Answer 21

6 C ring aldose

Question 22

Hydrogen bond donors and acceptors of all DNA bases (know the structures too)

Answer 22

hydrogen bond acceptors are N and O. Adenine contains 1 donor and 1 acceptor, thymine contains 1 donor and 1 acceptor, guanine contains 2 donors and 1 acceptor, and cytosine contains 1 donor and 2 acceptors.

Question 23

Thermal denaturation experiments can be used to follow the transition of double-stranded DNA into single-stranded DNA. Which of the following parameters affects the Tm of dsDNA in this experiment?

pH of solution
Ionic strength of solution
Length of DNA strands

Answer 23

All

The answer is D because all of these parameters would affect the thermodynamic stability of the DNA double helix. Significant drops in pH would result in protonation of hydrogen-bond acceptors, leading to a loss in base-pairing interactions. The presence of positive ions in solution (particularly Mg2+) leads to stabilization of the DNA fold via shielding of the repulsion between phosphate groups within the DNA backbone. The length of DNA strands would also play a role. Longer DNA strands are held together by more hydrogen bonds, meaning that more energy is required to denature the double-stranded DNA.

Question 24

Which is heavier: guanosine or deoxyguaosine

Answer 24

deoxy

Adenosine = adenine + ribose sugar

deoxyadenosine = adenine + deoxyribose sugar (has one less OH group, and has H instead)

Question 25

The side chain of which amino acid can form a bond that is similar to a peptide bond?

Answer 25

lysine

The answer is C because the lysine side chain can form isopeptide bonds by reacting with a carboxylic acid group, which is the same way that peptide bonds are formed.

Question 26

Substituting residues in a peptide with which amino acid will most likely result in a peptide with an increased pI?

Answer 26

lysine

The answer is A because Lys is a basic residue, meaning it would contribute to a high pI. Glu is an acidic residue, meaning it would contribute to a low pI. Gln and Val are both neutral. They would not contribute to the pI.

Question 27

Reducing vs nonreducing sugar

Answer 27

Any carbohydrate that is capable of causing the reduction of some other substances without being hydrolyzed first is the reducing sugar whereas sugars that do not possess a free ketone or an aldehyde group are called the non-reducing sugar.

Question 28

homodimer result on native PAGE and SDS-PAGE

Answer 28

one band for both