Question 1

Which of the following best describes the amphipathic nature of phospholipids and its importance for membrane structure?

Accepted Answer

Phospholipids have a hydrophilic head and two hydrophobic tails, enabling them to form bilayers that create a permeability barrier.

Question 2

A patient with a genetic disorder affecting the synthesis of cardiolipin would most likely experience defects in which cellular process?

Accepted Answer

ATP production in mitochondria

Question 3

Which of the following statements about membrane fluidity is correct?

Accepted Answer

Cholesterol acts as a fluidity buffer, preventing drastic changes in membrane fluidity with temperature shifts.

Question 4

A researcher observes that a certain membrane protein can be easily removed from the plasma membrane by changing the ionic strength of the solution. This protein is most likely:

Accepted Answer

A peripheral membrane protein

Question 5

Which of the following best explains why glycolipids are typically found on the outer leaflet of the plasma membrane?

Accepted Answer

Their carbohydrate groups are involved in cell-cell recognition and signaling with the extracellular environment.

Question 6

Which of the following is a direct consequence of the presence of cholesterol in animal cell membranes?

Accepted Answer

Decreased tendency of membranes to gel upon cooling

Question 7

A mutation that prevents the glycosylation of membrane proteins would most directly affect which of the following cellular processes?

Accepted Answer

Cell-cell recognition and adhesion

Question 8

Which of the following best describes the role of lipid rafts in the plasma membrane?

Accepted Answer

They are dynamic microdomains that organize signaling molecules and facilitate cell signaling.

Question 9

Which equation would you use to calculate the transition temperature ($$T_m) of a $$membrane, and what factors influence $$T_m$$?

Accepted Answer

$$T_m = \frac{\Delta H}{\Delta S}$$; chain length and degree of saturation of fatty acids influence $$T_m.$$

Question 10

A cell is exposed to a temperature below its membrane's $$T_m. $$What is the most likely consequence?

Accepted Answer

The membrane becomes more rigid, disrupting processes that require fluidity.

Question 11

Which of the following best explains why unsaturated fatty acids increase membrane fluidity?

Accepted Answer

Their cis double bonds introduce kinks, preventing tight packing of lipid tails.

Question 12

Which of the following is a function of the glycocalyx in animal cells?

Accepted Answer

Providing a permeability barrier, mediating cell-cell recognition, and protecting the cell surface

Question 13

A scientist uses fluorescence recovery after photobleaching (FRAP) to study membrane protein mobility. What does rapid fluorescence recovery indicate?

Accepted Answer

Proteins are freely diffusing within the membrane.

Question 14

Which of the following best describes the orientation of membrane proteins in the lipid bilayer?

Accepted Answer

Membrane proteins are asymmetrically oriented and cannot move from one side of the bilayer to the other.

Question 15

Which of the following is a real-life consequence of altered membrane lipid composition in human disease?

Accepted Answer

Changes in membrane $$T_m$$ can affect cell signaling pathways and contribute to tumor progression in cancer.

Question 16

Which of the following proteins is most likely to induce membrane curvature during vesicle formation?

Accepted Answer

BAR domain-containing proteins

Question 17

Which of the following best describes the function of gap junctions in animal cells?

Accepted Answer

They allow for direct communication between adjacent cells by permitting the passage of ions and small molecules.

Question 18

A diet high in saturated fats is most likely to have which effect on plasma membrane properties?

Accepted Answer

Increase membrane rigidity and raise the transition temperature ($$T_m)$$

Question 19

Which of the following best explains why membrane asymmetry is maintained over time?

Accepted Answer

Transverse diffusion is rare and requires specific enzymes called flippases.

Membranes: Structure, Function, and Chemistry – Study Notes

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