Question 1

Which component of a phospholipid is responsible for its 'love-hate' relationship with water?

Accepted Answer

The polar phosphate group, which is hydrophilic, and the nonpolar fatty acid tails, which are hydrophobic

Question 2

What is the primary reason phospholipids spontaneously form bilayers in aqueous environments?

Accepted Answer

Hydrophobic interactions among fatty acid tails and hydrophilic interactions of phosphate groups with water

Question 3

Which of the following best describes the fluid mosaic model of the plasma membrane?

Accepted Answer

A dynamic structure with lipids and proteins able to move laterally and rotate within the membrane

Question 4

How does cholesterol affect membrane fluidity at different temperatures?

Accepted Answer

It stabilizes the membrane by reducing fluidity at high temperatures and preventing solidification at low temperatures

Question 5

Which type of membrane protein is embedded within the hydrophobic core of the lipid bilayer?

Accepted Answer

Integral (transmembrane) proteins

Question 6

A mutation causes the fatty acid tails of phospholipids in a cell membrane to become longer and more saturated. What is the most likely effect on membrane fluidity?

Accepted Answer

Membrane fluidity will decrease

Question 7

Which process requires the enzyme flippase in the plasma membrane?

Accepted Answer

Translocation of phospholipids from one leaflet to the other

Question 8

Why are glycolipids and glycoproteins important for cell membranes?

Accepted Answer

They serve as markers for cell recognition and communication

Question 9

Which of the following equations best represents the relationship between membrane fluidity ($$F$$), temperature ($$T$$), and the degree of saturation of fatty acid tails ($$S$$)?

Accepted Answer

$$F = \frac{k 	imes T}{S}$$

Question 10

A scientist observes that a certain cell type has a high percentage of transmembrane proteins. What function is most likely enhanced in these cells?

Accepted Answer

Transport of molecules across the membrane

Question 11

Which of the following best explains why phospholipids are described as amphipathic molecules?

Accepted Answer

They contain both hydrophilic and hydrophobic regions

Question 12

If a cell is placed in a cold environment, which membrane adaptation would help maintain fluidity?

Accepted Answer

Increase the proportion of unsaturated fatty acid tails

Question 13

Which of the following is NOT a function performed by membrane proteins?

Accepted Answer

Synthesis of fatty acids

Question 14

A patient has a genetic disorder that prevents glycosylation of membrane proteins. Which cellular process is most likely to be impaired?

Accepted Answer

Cell recognition by the immune system

Question 15

Which of the following statements about membrane sidedness is correct?

Accepted Answer

The extracellular side of the membrane is enriched in glycosylated lipids and proteins

Question 16

Which organism is most likely to have the highest percentage of genes encoding transmembrane proteins?

Accepted Answer

Escherichia coli

Question 17

A cell membrane is described as 'semifluid.' What does this mean?

Accepted Answer

Lipids and proteins can move laterally and rotate, but rarely flip-flop between leaflets

Question 18

Which of the following best describes the role of hydrophobic interactions in membrane structure?

Accepted Answer

They drive the fatty acid tails to avoid water and aggregate in the membrane interior

Question 19

Which equation best represents the effect of cholesterol ($$C) on $$membrane fluidity ($$F) at $$high temperature ($$T_{high}) $$and low temperature ($$T_{low}$$)?

Accepted Answer

$$F_{T_{high}} = F_0$ - kC$$

Structure and Function of Biological Membranes

Guida di studio - Domande di pratica

Study guide - Flashcard