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AAMC Review > AAMC MCAT C/P > Flashcards

AAMC MCAT C/P Flashcards

1
Q

antagonist

A

is a substance that interferes with or inhibits the physiological action of another.

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2
Q

agonist

A

a substance which initiates a physiological response when combined with a receptor.

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3
Q

The formula for finding the maximum number of stereoisomers:

A

X is X = 2n, where n is the number of stereogenic atoms in the molecule.

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4
Q

Squalene is produced in the human body as a precursor to which important class of compounds?

A

Steroid hormones

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5
Q

reverse-phase high performance liquid chromatography (HPLC) what should be the properties of the stationary phase?

A

Nonpolar

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6
Q

When performing regular-phase HPLC what should be the properties of the stationary phase?

A

Polar

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7
Q

HPLC

A

HPLC separates compounds based on polarity and solubility in the stationary phase. In regular-phase HPLC, the stationary phase is polar, and the mobile phase is nonpolar (similar to typical thin-layer chromatography). In reverse-phase HPLC, the stationary phase is nonpolar, and the mobile phase is polar

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8
Q

Would it be possible for the researchers to use gas chromatography (GC) for the isolation of retinol during SRA?

A

Yes, provided retinol can be vaporized without degradation.

In gas chromatography, samples are heated and vaporized before they are introduced into the separating column. Therefore, they must be able to be vaporized without being broken down or combusting so they can be analyzed properly in the gaseous phase.

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9
Q

In an experiment in which retinol must be isolated by extraction, in which solvent would one expect it to dissolve most readily?

A

Hexane (nonpolar)

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10
Q

In order to image target blood vessels, researchers must first determine the index of refraction of skull bone. What is the minimum information required to make this determination?

A

The velocity of light in the sample

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11
Q

Complete hydrolysis of every bond in the ethyl chains on the end of the diethyl phthalate molecules would:

A

result in hydrogen bonding.

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12
Q

Methane gas is nonpolar. What are the possible implications of this?

A

Being nonpolar, dipole-dipole forces will not be present.

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13
Q

What molecules are dipole-dipole forces present in?

A

Dipole-dipole forces are present only between polar molecules

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14
Q

It was attempted to use dipropyl ether as a solvent and diethyl phthalate as a solute. Dipropyl ether is nonpolar. What results might be expected, assuming that the diethyl phthalate dissolved as intended?

A

Induced dipole interactions between dipropyl ether and diethyl phthalate

Diethyl phthalate is a polar molecule and will induce a dipole in neighboring nonpolar molecules. As such, a permanent dipole will exist next to a temporary dipole, and the two will then attract each other due to electrostatic force (the attractive force between positively-charged and negatively-charged atoms). The name for this phenomenon is “induced-dipole” interactions.

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15
Q

The blood-brain barrier prevents molecules from easily entering the central nervous system unless they are able to pass through the lipophilic plasma membranes of the cells making up the barrier. Which of the following is most likely to be true?

A

Diethyl phthalate is more likely to cross the blood-brain barrier than phthalic acid because it lacks hydrogen-bonding hydroxyl groups.

The plasma membrane permits molecules to pass through if they are nonpolar (for example, steroid hormones). Diethyl phthalate is less polar than phthalic acid, as it lacks the -OH groups that phthalic acid has.

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16
Q

Blood-Brain Barrier

A

The plasma membrane permits molecules to pass through if they are nonpolar (for example, steroid hormones)

the blood-brain barrier, where the epithelial cells in blood vessels in the brain form very tight junctions that allow the very close regulation of which substances from the bloodstream can enter the central nervous system. Among other substances, the blood-brain barrier blocks the diffusion of most drugs into the brain, which poses serious problems for researchers who are trying to develop drugs targeting neurological diseases. Lipophilic compounds are more likely to diffuse past the blood-brain barrier, because they can move through the plasma membranes of the epithelial cells.

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17
Q

double-replacement reaction

A 
occurs when parts of two ionic compounds are exchanged, making two new compounds. A characteristic of a double-replacement equation is that there are two compounds as reactants and two different compounds as products. An example is.
 CuCl 2(aq) + 2 AgNO 3(aq) → Cu(NO 3) 2(aq) + 2 AgCl(s)
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18
Q

Lewis acid-base reaction

A

bases donate pairs of electrons and acids accept pairs of electrons. A Lewis acid is therefore any substance, such as the H+ ion, that can accept a pair of nonbonding electrons. In other words, a Lewis acid is an electron-pair acceptor.

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19
Q

An ultrasound examination could show the motion of a fetus. In order to image this motion, the ultrasound examination devices requires what minimal information?

A

The speed of the sound, and the frequencies of the sound waves emitted and observed.

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20
Q

Why is the boiling point of HF is abnormally high when compared to the boiling points of other Group 7A hydrides?

A

HF is affected by hydrogen-bonding interactions to a much greater degree than the other Group 7A hydrides.

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21
Q

The principal quantum number is a measure of:

A

Approximate radial size of an electron cloud!

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22
Q

infrared spectrum for carboxyl group C=O stretching frequency falls in what region?

A

1700–1750 cm–1

23
Q

infrared spectrum for carboxyl group O–H stretching frequency falls in what region?

A

3200–3500 cm–1

24
Q

Myopia is a condition of the eye where the crystalline lens focuses the light rays to a position between the lens and the retina. To correct for this condition, a thin lens is placed in front of the eye that will help to focus light on the retina. The type of lens required is:

A

diverging.

25
Q

squalene is a

A

steroid precursor

26
Q

glucose is a

A

carbohydrate precursor

27
Q

One method of isolating polypeptides and proteins from aqueous extracts is freeze drying. The aqueous solution of the polypeptide or protein is frozen. What procedure can be used to remove the water from the frozen sample?

A

Sublimation under reduced pressure

28
Q

In oxidative phosphorylation, cytochrome c acts as:

A

a 1-electron carrier.

29
Q

Which primer is most suitable for PCR?

A

suitable primers have a high GC content and have G or C base pairs at the 5’ and 3’ends.

30
Q

In which phase of meiosis does nondisjunction occur?

A

Anaphase I

31
Q

What type of isomers are used to form proteins during ribosomal protein synthesis?

A

only L isomers are used to form proteins during ribosomal protein synthesis

32
Q

Yeast cells can grow under either aerobic or anaerobic conditions. If the same concentration of glucose were used to grow two different yeast colonies, would the growth rate be faster under aerobic or anaerobic conditions?

A

Aerobic, because a much greater amount of ATP would be produced to provide energy for reproduction

33
Q

If the GAPDH gene is continuously expressed, where is it most likely found?

A

In euchromatin

34
Q

The genes for red-green color blindness will affect production of proteins in which of the following types of cells?

A

Visual receptor cells in the retina

35
Q

The individual cells making up a tissue differ from single-celled organisms such as Paramecium in that only the latter:

A

are capable of extended independent life.

36
Q

A fatty acid is comprised of a long hydrocarbon tail and a head consisting of:

A

a carboxyl group.

37
Q

In humans, the lining of which structure is NOT primarily derived from the endoderm?

A

Mouth

38
Q

Which of the following peptides is most likely to form a covalently bonded dimer?

AVTSYWP
GHICEPN
NFMNELI
ELIPWQN

A

GHICEPN

39
Q

To determine a protein’s thermodynamic stability, chemical denaturation studies can be performed. Assuming that only the native and unfolded states can be observed under experimentally available conditions, what is the most likely shape of the curve for the dependence of the fraction of folded protein upon denaturant concentration?

A

Sigmoidal

The unfolding of proteins is a cooperative process. Cooperative processes are marked by sigmoidal curves

40
Q

A combination of KM and kcat with which relative values is indicative of the lowest catalytic efficiency for an enzymatically catalyzed reaction?

A high KM and a low kcat
A high KM and a high kcat
A low KM and a high kcat
A low KM and a low kcat

A

A high KM and a low kcat

Catalytic efficiency is measured by Kcat/Km, which means that a higher Km and a lower Kcat gives the lowest efficiency

41
Q

How is catalytic efficiency is measured?

A

Catalytic efficiency is measured by Kcat/Km

42
Q

Which extraction procedure will completely separate an amide from the by-product of the reaction between an amine and excess carboxylic acid anhydride?

A

Add 0.1 M NaOH(aq) to quench unreacted anhydride. Then add diethyl ether and separate the layers. The amide can be obtained from the ether layer by evaporating the solvent.

43
Q

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

A

[Ar] 3d7

44
Q

Which cation is most likely to be found in place of Fe(II) in the square planar binding domain of hemoglobin?

A

Co2+

45
Q

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

A

Transferase

46
Q

The idea that enzymes undergo conformational changes upon substrate binding in order to bring specific functional groups into the correct catalytic orientation is described as the:

A

induced-fit model.

The induced-fit model of enzyme catalysis states that the active site of the enzyme changes shape upon substrate binging and only the proper substrate causes a change that initiates catalysis.

47
Q

When performing experiments to measure the kcat of an enzyme, the substrate concentration should be:

A

saturating

The kcat is used to describe the rate-limiting step of catalysis under saturating conditions of substrate.

48
Q

When experiments are performed on enzymes that display traditional Michaelis–Menten kinetics, what shape does the graph of V0 versus substrate concentration [S] have?

A

A hyperbolic dependence on [S]

traditional Michaelis–Menten kinetics describes a hyperbolic dependence of V0 on substrate concentration.

49
Q

Which experimental results confirm that Compound 1 is an uncompetitive inhibitor of a particular enzyme? In the presence of Compound 1:

A

both the KM and Vmax decrease.

the presence of an uncompetitive inhibitor results in a lower apparent KM and Vmax of the enzymatically catalyzed reaction

50
Q

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

A

4 moles of NADH for each mole of protein.

each mole of NADH can reduce a mole of disulfide bonds. Since the protein has four disulfide bonds, four moles of NADH are needed

51
Q

The relationship between the steroid hormone, estrogen, and the peptide hormone, insulin, is being investigated. In order to quantify levels of each of these hormones, tissue samples were homogenized and then placed in a mixture of 2:1 hexane/water. What is the expected result from this extraction method?

A

Estrogen would be in the hexane phase; insulin would be in the aqueous phase.

the structural features of peptides and steroids imply that insulin is hydrophilic and estrogen is hydrophobic. The hydrophilic insulin peptide would be expected to be found in the aqueous phase, while the hydrophobic estrogen hormone would segregate into the hexane phase.

52
Q

Which of the four DNA bases contains the largest number of hydrogen bond acceptors when involved in a Watson–Crick base pair?

A

C

53
Q

Which nucleoside has the largest molecular weight?

A

Guanosine

54
Q

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

A

Lys

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

AAMC Review (1 decks)

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