Question 1

Which of the following best explains how cholesterol affects membrane fluidity in animal cells at different temperatures?

Accepted Answer

Cholesterol prevents membrane rigidity at low temperatures and prevents excess fluidity at high temperatures.

Question 2

A mutation causes a cell to lack flippase enzymes. Which process would be most directly affected?

Accepted Answer

Flip-flop of phospholipids between membrane leaflets

Question 3

A red blood cell is placed in a hypertonic solution. Which of the following best describes what happens to the cell?

Accepted Answer

The cell shrinks as water leaves by osmosis.

Question 4

Which of the following is a function of glycolipids and glycoproteins in the plasma membrane?

Accepted Answer

Determining cell recognition and ABO blood type

Question 5

During SDS-PAGE, what is the primary purpose of sodium dodecyl sulfate (SDS)?

Accepted Answer

To denature proteins and impart a uniform negative charge

Question 6

Which equation best describes the rate of simple diffusion across a membrane?

Accepted Answer

$$ J = P (C_1$ - C_2$) $$

Question 7

A cell uses the Na⁺/K⁺ pump to maintain ion gradients. Which type of transport is this, and what is the energy source?

Accepted Answer

Primary active transport; ATP hydrolysis

Question 8

Which of the following statements about membrane proteins is correct?

Accepted Answer

Integral proteins are embedded within the lipid bilayer.

Question 9

A patient with a genetic defect in aquaporin proteins would most likely experience problems with which process?

Accepted Answer

Osmosis of water across cell membranes

Question 10

Which of the following best describes the role of Rab GTPases in vesicle trafficking?

Accepted Answer

They identify the target membrane for vesicle fusion.

Question 11

A protein with a KDEL sequence is found in the Golgi. What will happen to this protein?

Accepted Answer

It will be returned to the ER.

Question 12

Which of the following is NOT a component of the endomembrane system?

Accepted Answer

Chloroplast

Question 13

During muscle contraction, which sequence of events occurs after Ca²⁺ binds to troponin?

Accepted Answer

Tropomyosin shifts, myosin binds actin, power stroke, filaments slide

Question 14

Which cytoskeletal element is responsible for forming the mitotic spindle during cell division?

Accepted Answer

Microtubules

Question 15

Which of the following statements about intermediate filaments is correct?

Accepted Answer

They provide tensile strength and are rope-like.

Question 16

Dynamic instability is a property unique to which cytoskeletal element?

Accepted Answer

Microtubules

Question 17

Which equation best describes the Michaelis-Menten kinetics for carrier-mediated transport?

Accepted Answer

$$ v = V_{max} \frac{[S]}{K_m + [S]} $$

Question 18

Which of the following is true regarding the orientation of membrane proteins during trafficking?

Accepted Answer

The N-terminus facing the cytosol in the ER will remain cytosolic at the plasma membrane.

Question 19

Which of the following is a characteristic of lipid rafts?

Accepted Answer

They are enriched in cholesterol and sphingolipids and serve as signaling platforms.

Question 20

Which motor protein moves toward the plus end of microtubules, and what is its energy source?

Accepted Answer

Kinesin; ATP hydrolysis

Cell Membranes, Transport, Endomembrane System, and Cytoskeleton: Structured Study Notes

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