AAMC B/BC Section Bank-done

Question 1

The stereochemical designators α and β distinguish between:

Answer 1

epimers at an anomeric carbon

The answer to this item is C since the α versus β designation distinguishes between molecules with multiple chiral centers, but differ only in the configuration of the site known as the anomeric carbon atom.

Question 2

Which ideal solution exhibits the greatest osmotic pressure?

0. 1 M MgCl2
1. 2 M NaCl
2. 2 M CaCl2
3. 5 M glucose

Answer 2

The answer to this question is C because the solution listed has the greatest concentration of solute particles. CaCl2 dissociates into three ions, making the solution listed 0.6 M in solute particles.

Question 3

Which event is directly mediated by a ligand-gated ion channel?

Answer 3

Influx of Na+ across the motor end plate resulting in the depolarization of the muscle fiber membrane

The answer to this question is C because the influx of Na+ across the motor end plate occurs when Na+ ion channels bind the ligand acetylcholine.

Question 4

A single point mutation in a gene results in a nonfunctional protein. Individuals heterozygous for this mutation were identified using a Southern blot. Which pair of wild-type (WT) and mutant alleles most likely contains the mutation?

Answer 4

The answer to this question is A because a Southern blot uses a restriction digest to differentiate between mutant and wild-type alleles. In order for a Southern blot to be useful, the mutation should either create or eliminate a restriction site, most of which are palindromes and 4 to 6 base pairs long. The mutation shown in this option is the only one that disrupts a palindromic sequence, AAGCTT. This sequence is the recognition sequence for HindIII.

Question 5

One amino acid is ____ daltons.

Answer 5

110Da (g/mol)

Question 6

Nativs, non-reducing, reducing

Answer 6

Native-page: everything in-tact, separated by size and charge or shape like you said. ie. If we had a heterotrimer, we only would see one band.

SDS-page non-reducing(w/o B-ME): S-S are intact but protein is denatured ie. If we had a heterotrimer, we would only see one band.

SDS-page reducing (w/ B-ME): S-S become reduced protein is still dentured. ie. If we had a heterotrimer, we would see 3 separate bands.

Question 7

Native, non-reducing, reducing

Answer 7

Native-page: everything in-tact, separated by size and charge or shape like you said. ie. If we had a heterotrimer, we only would see one band.

SDS-page non-reducing(w/o B-ME): S-S are intact but protein is denatured ie. If we had a heterotrimer, we would only see one band.

SDS-page reducing (w/ B-ME): S-S become reduced protein is still dentured. ie. If we had a heterotrimer, we would see 3 separate bands.

Question 8

Small Kd means

Answer 8

Small Kd = high affinity because smaller concentration of substrate required to saturate 50% of the enzyme available

Question 9

Small Kd means

Answer 9

Small Kd = high affinity because smaller concentration of substrate required to saturate 50% of the enzyme available

Question 10

cDNA has no ____

Answer 10

introns

Question 11

A characteristic of noncompetitive inhibitors is that they bind the enzyme and the enzyme–substrate complex with the ___ affinity; Vmax is affected, but KM does not change.

Answer 11

same

Question 12

For isoelectric focusing, which separates proteins based on isoelectric point, a stable _____ must be established in the gel.

Answer 12

pH gradient

Question 13

Ovarian cells are _____ cells, and osteoclasts are ______ cells

Answer 13

epithelial, connective tissue

Question 14

Peptide hormones are ____ and _____ in blood. Hormones that must bind transport proteins are steroid proteins, which are lipophilic.

Answer 14

hydrophilic and soluble

Question 15

uncompetitive inhibitors bind their target enzymes only when ___________________

Answer 15

the substrate is first bound to the enzyme

Question 16

cytochrom c is associated with the mitochondrial inner membrane, where it functions in the _____ _____ ______.

Answer 16

electron transport chain

Question 17

_________ is one of the mitochondrial proteins that is released into the cytosol when the cell is activated by an apoptotic stimulus.

Answer 17

Cytochrome c

Question 18

methods of separating proteins

Answer 18

isoelectric focusing separates proteins based on their isoelectric point (the pH at which the net charge of the protein is zero) and ion exchange chromatography separates proteins based on their net charge. In contrast SDS-PAGE separates proteins based on their mass and affinity chromatography separates proteins based on their interactions with specific ligands.

Question 19

methods of separating proteins

Answer 19

isoelectric focusing separates proteins based on their isoelectric point (the pH at which the net charge of the protein is zero) and ion exchange chromatography separates proteins based on their net charge. In contrast SDS-PAGE separates proteins based on their mass and affinity chromatography separates proteins based on their interactions with specific ligands.

Question 20

know citric acid cycle and glycolysis

Answer 20

know like how many reduced electron carriers between steps of citric acid cycle and know which enzymes are different between glycolysis and gluconeogenesis

Question 21

___________ is not used in cDNA cloning, while ________ are used

Answer 21

RNA polymerase

while DNA polymerase (in DNA amplification), DNA ligase (in ligation of the cDNA to DNA vector) and reverse transcriptase (in reverse transcription of RNA to cDNA) are used during cDNA cloning

Question 22

____, _____, and _____ are used as starting materials in gluconeogenesis

Answer 22

lactate, oxaloacetate, and α-ketoglutarate

Question 23

______ is the enzyme that catalyzes the rate-limiting step in glycogen breakdown (glycogenolysis)

Answer 23

Glycogen phosphorylase

-know glycogenolysis

Question 24

______ is the enzyme that catalyzes the rate-limiting step in glycogen breakdown (glycogenolysis)

Answer 24

Glycogen phosphorylase

-know glycogenolysis

Question 25

_____ is composed of two major bonds, which are _____ and _____ - these bonds give rise to linear chains and branching points, respectively.

Answer 25

Glycogen, alpha-1,4 and alpha-1,6 glycosidic bonds

Question 26

while kinase catalyzes the addition of a phosphate group to a substrate, the removal of the phosphate groups are catalyzed by a _____

Answer 26

phosphatase

Question 27

while kinase catalyzes the addition of a phosphate group to a substrate, the removal of the phosphate groups are catalyzed by a _____

Answer 27

phosphatase

Question 28

enzyme that puts a phosphate onto a substrate would be called a ____

Answer 28

kinase

Question 29

A _____ takes a phosphate OFF of a substrate, hydrolyzing it to yield phosphoric acid.

Answer 29

“phosphatase”

Question 30

A ______ puts a phosphate ONTO a substrate, in a special way

Answer 30

“phosphorylase”

Question 31

the pentose phosphate pathway results in the generation of ______, which is utilized in _____ reactions

Answer 31

NADPH, reductive

Question 32

know enzyme functions, all pathways, lab tests, AAs, know like the opposite strand stuff (coding strand, sense strand, mrna, dna, cdna, etc.)

Question 33

free radical scavengers _______ the effects of reactive oxygen species

Answer 33

mitigate

Question 34

lipoic acid is a cofactor for the enzyme______ which catalyzes the conversion of pyruvate to acetyl-CoA

Answer 34

pyruvate dehydrogenase

Question 35

In the pentose phosphate pathway, which enzyme catalyzes the production of 6-phosphogluconolactone?

Answer 35

Glucose 6-phosphate dehydrogenase

Question 36

______ is a technique used to detect a particular sequence in a sample of DNA and CANNOT be used to analyze ________

Answer 36

Southern blotting, gene expression