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MCAT Review 🩺💕 > Chemistry > Flashcards

Chemistry Flashcards

(73 cards)

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1
Q

Bose–Einstein Principle

A

A collection of atoms cooled close to absolute zero will coalesce into a single quantum state.

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2
Q

Pauli Exclusion Principle

A

Two or more identical fermions, e.g. electrons, cannot occupy the same quantum state

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3
Q

Heisenberg Uncertainty Principle

A

One cannot know both the momentum and position of an object with absolute certainty.

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4
Q

Le Châtelier’s Principle

A

In a reversible process, the application of stress to the system will cause the system to respond in a way that will relieve this stress.

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5
Q

Competitive Ki represents

A

Binding to free enzyme (E)

Forms EI complex

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6
Q

Uncompetitive Ki represents

A

Binding to enzyme–substrate complex (ES)

Forms ESI complex

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7
Q

Increasing polarity means more. . .

A

Water soluble

Changing benzene CH to N within ring

The more H-bonds you can form the more water soluble you are

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8
Q

Na+-NQR

A

It catalyzes the oxidation of NADH and the reduction of quinone to quinol.

It translocates Na+ ions across the membrane, creating a sodium motive force.

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9
Q

RC(=O)R → RCH(OH)R

A

Na+-NQR acts as a catalysis

This is a carbonyl (ketone-like) to alcohol transformation — the hallmark of quinone reduction.

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10
Q

ROPO₃²⁻ → ROH + Pi

A

Hydrolysis of a phosphate ester, releasing inorganic phosphate (Pi).

Phosphatase

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11
Q

RC(=O)NHR′ → RCOOH + R′NH₂

A

This is amide hydrolysis into a carboxylic acid and an amine.

Typical in protease reactions, amidase reactions, or in acid/base catalysis

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12
Q

RC(=O)OR′ → RCOOH + R′OH

A

This is ester hydrolysis into a carboxylic acid and an alcohol.

Common in lipase reactions (fat digestion) or base-catalyzed hydrolysis (saponification).

Esterase

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13
Q
A

This is the structure of adenine.

Found in FAD

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14
Q
A

This is the structure of flavin, found in four of the five cofactors used by Na+-NQR

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15
Q
A

This is the structure of ubiquinone.

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16
Q
A

This is the structure of histidine.

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17
Q

How do cells prevent exergonic reactions (like NADH oxidation) from releasing excess heat and wasting energy? What role does coupling play?

A

Cells couple exergonic reactions to endergonic processes

This coupling reduces net heat release by using the free energy to do biological work, rather than dissipating it as heat.

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18
Q

Hess’s Law

A

The heat of reaction will sum and be the same. The fact that the reaction can be broken down into steps will not change the overall thermodynamics.

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19
Q

How does container shape affect the pressure at a given depth in a liquid?

A

It doesn’t! Hydrostatic pressure only depends on:
• Depth h
• Density \rho
• Gravitational acceleration g

P = \rho g h

The shape or total volume of the container does not affect pressure at a specific depth. Two different-shaped containers holding the same liquid will have equal pressure at equal depths.

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20
Q

What is Pascal’s Law, and how does it explain pressure changes in an enclosed fluid? What equation relates force and area in hydraulic systems?

A

A change in pressure applied to an enclosed, incompressible fluid is transmitted undiminished throughout the fluid and to the walls of the container.

If you apply pressure to one part of a fluid (like pushing on a syringe plunger), that same pressure change spreads evenly throughout the entire fluid — no matter the shape or size of the container.

📌 Key Equation (Hydraulic Systems):
F1/A1 = F2/A2

Used to calculate how a small force on a small piston can produce a large force on a large piston.

🧠 MCAT Tip: Applies in questions about hydraulic lifts, brake systems, syringes, or pressure transfer in enclosed fluids.

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21
Q

What is the identity of an atom that contains six protons and eight neutrons?

A

Carbon

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22
Q

Nitrogen contains how many protons?

A

7

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23
Q

Carbon contains how many protons?

A

6

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24
Q

Oxygen contains how many protons?

A

8

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25
Silicon contains how many protons?
14
26
Is NF3 polar? Why or why not?
The geometry of trifluoroamine is impacted by the lone pair on nitrogen, making it trigonal pyramidal. No bond dipoles cancel; this results in a polar molecule.
27
Is CCl4 polar? Why or why not?
While each C–Cl bond in carbon tetrachloride is polar, the sum of the dipole moments cancel as a result of its tetrahedral molecular geometry.
28
Is carbon dioxide polar? Why or why not?
Carbon dioxide is a linear molecule. The bond dipole moments of each C=O bond cancel as they are in opposite directions.
29
If all else is held constant, which of the following changes would NOT double the volume of a gas? A.Doubling the pressure B.Doubling the absolute temperature C.Halving the pressure D.Doubling the number of gas molecules
A
30
Based on Boyle's Law, P is inversely proportional . . .
to volume, thus, doubling the pressure of a gas sample will decrease, not increase, the volume.
31
Avogadro’s Law How does the number of moles (or gas molecules) affect volume?
Doubling the number of gas molecules (moles) ⇒ doubles the volume V is directly proportional to n
32
Charles’s Law How does temperature affect volume for an ideal gas?
Temperature must be in Kelvin (absolute temp) Doubling Kelvin temperature ⇒ doubles volume
33
Boyle’s Law How does pressure affect gas volume if temperature and number of moles are constant?
Doubling pressure halves volume Halving pressure doubles volume ✅ So doubling pressure will NOT double volume — it does the opposite. P inversely proportional to V
34
Ideal Gas Law
PV = nRT
35
Z
Atomic Number Number of protons
36
A
Mass number Protons + Neutrons
37
Number of Neutrons =
A - Z
38
What makes pyrrole a heterocyclic aromatic compound?
It’s a heterocycle (contains nitrogen) It’s aromatic (6 π electrons) Molecular formula: C₄H₅N
39
What is the structure and molecular formula of pyrrole?
Five-membered ring: 4 carbon atoms, 1 nitrogen atom Aromatic: 6 π electrons (from 2 double bonds + lone pair on N) Formula: C₄H₅N
40
What does 22.4 L mean?
What does 22.4 L mean?
41
How do you calculate moles of gas from volume at STP?
Moles = Volume (cm3) / 22,400 cm3
42
Can 605 nm radiation cause fluorescence emission at 604 nm?
No, because 605 nm has less energy than 604 nm. Absorbed light must have more energy than emitted fluorescence. Fluorescence can occur when the absorbed radiation has a photon energy larger than the photon energy of the radiation emitted through fluorescence. The photon energy is inversely proportional to the radiation wavelength, thus the 605-nm wavelength radiation cannot produce the entire fluorescence radiation spectrum shown in Figure 3 as its photon energy is below that of the fluorescence radiation of wavelength 604 nm.
43
How are light energy and wavelength related?
Energy is inversely proportional to wavelength: E = hc/ λ → Shorter wavelength = higher energy
44
What condition must be true for fluorescence to occur?
The energy of the absorbed radiation must be greater than the energy of the emitted fluorescence radiation.
45
Fluorescence happens when:
A molecule absorbs light (high energy, short wavelength), Then releases some of that energy as heat Emits light (lower energy, longer wavelength).
46
In a protein, each amino acid residue, except Gly, has a. . .
chiral α carbon.
47
What physical property does NOT change in the L49S mutation of TPMT*5?
Net charge. Both Leucine and Serine are uncharged, so the net charge of the protein is unchanged.
48
What gel band pattern is characteristic of proteolysis over time?
Disappearance of the high-molecular-weight band (full-length protein) and appearance of multiple low-molecular-weight bands (cleaved fragm
49
How does protein aggregation appear on an SDS-PAGE gel over time?
Formation of new high-molecular-weight bands or smearing upward; no significant increase in low-molecular-weight bands.
50
What is the net change in molecular weight when a methyltransferase enzyme like TPMT transfers a methyl group from a cofactor (like SAM) to a substrate?
0 g/mol. The methyl group (15 g/mol) is transferred, not lost. The cofactor loses the methyl group and the substrate gains it, so the total molecular weight remains unchanged.
51
The steroid hormone progesterone binds to hMPRα. Which compound is it derived from?
Cholesterol. Progesterone is a steroid hormone, and all steroid hormones are synthesized from cholesterol.
52
Cation exchange
Separates based on positive charges on the protein
53
Anion exchange
Separates based on negative charges
54
What structural feature of detergents allows them to extract membrane proteins from lipid bilayers?
Detergents are amphipathic molecules, meaning they have: • Hydrophobic parts (interact with lipid membranes), • Hydrophilic parts (interact with water). This structure allows detergents to: • Insert into cell membranes, • Surround membrane proteins, • Form micelle-like structures that pull the protein into solution without destroying it.
55
Is the presence of a reducing sugar important for a detergent’s membrane-disrupting function?
No, the presence of a reducing sugar affects solubility and oxidation potential, but it’s not key to detergent activity.
56
What would be the downside of a detergent having multiple hydrolysable linkages?
It would make the detergent susceptible to degradation or metabolism, which could interfere with its ability to isolate proteins. Multiple hydrolysable linkages → That would make it easy to break down (metabolize), but we want stability during extraction, not breakdown.
57
Specific configuration of numerous chirality centers
Important for enzymes or ligands with highly specific binding, but not for detergents. They don’t need precise 3D shapes to work. Their action relies on general chemical properties, not stereospecific binding.
58
How do you calculate the number of moles in a solution using molarity and volume?
Moles = Molarity x Volume
59
What’s the best experimental evidence that a purified protein is still in its native state?
It retains the same functional activity (e.g., binding affinity) as the native version The only way to tell for certain that a protein is still in its native state is to compare its functioning to the levels observed for protein believed to be in the native state
60
Why does nuclear fusion require extremely high temperatures?
To give particles enough kinetic energy to overcome electrostatic repulsion and get close enough for the strong nuclear force to bind them. High temperature = fast-moving particles (higher average kinetic energy). Fast particles are more likely to get close enough for the strong nuclear force to take over and fuse the nuclei. This doesn’t eliminate charge or the strong force—it just helps particles overcome the energy barrier to get close.
61
Nuclear fusion
smashing two positively charged nuclei together to form a heavier nucleus and release energy. BUT: • Positive charges repel each other (this is called electrostatic repulsion or Coulomb repulsion). • The strong nuclear force is what holds nuclei together — but it only acts when particles are extremely close (within 1 femtometer = 10⁻¹⁵ meters). • So, to get close enough for the strong force to kick in, particles need a lot of kinetic energy to overcome the repulsion.
62
Enantiomers can exhibit a difference in which chemical or physical property? A.Density B.Boiling point C.Smell D.IR spectrum
C Enantiomers have the same physical and chemical properties. They differ only in their three dimensional arrangement of atoms and their interactions with other chiral molecules. They can differ in their smell due to interacting differently with chiral odorant receptors. What can be different? • Interactions with other chiral things, like: • Chiral receptors (like those in your nose → different smells!) • Chiral enzymes or drugs → different biological effects • Plane-polarized light → different rotation directions (they’re optically active)
63
What happens to the velocity of a fluid when the diameter of the tube is halved?
Velocity increases by a factor of 4 (because area ∝ diameter²).
64
Continuity Equation (conservation of volume flow rate)
65
How do you determine if a species has an electron configuration equivalent to a noble gas?
A species has a noble gas configuration if all of its electron shells are completely filled up to a noble gas level. • For neutral atoms, check if it is a noble gas. • For ions, check if electrons have been gained (anions) or lost (cations) to reach a full outer shell matching that of a noble gas.
66
You know an atom or ion has a noble gas configuration if . . .
its electron configuration ends with a completely filled outer shell
67
Imidazole
Found in histidine
68
How does protein denaturation affect accessibility of amino acid residues?
Denaturation exposes amino acid residues that were previously buried inside the protein.
69
Formate
HCO2⁻
70
Carbonate
CO3²⁻
71
Bicarbonate
HCO3⁻
72
Acetate
CH3CO2⁻
73
Cells couple exergonic reactions to endergonic processes, such as:
• Ion transport against gradients • Mechanical work • Synthesis of high-energy molecules

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