Question 1

Which of the following best describes the role of pyrophosphate hydrolysis in membrane phospholipid synthesis?

Accepted Answer

It provides the energy to drive the addition of headgroups to diacylglycerol.

Question 2

During the synthesis of phosphatidylserine, which molecule acts as the immediate precursor?

Accepted Answer

Phosphatidylserine is synthesized from phosphatidylethanolamine by a headgroup exchange reaction.

Question 3

Which enzyme catalyzes the conversion of diacylglycerol to phosphatidic acid in the phospholipid synthesis pathway?

Accepted Answer

Acyltransferase

Question 4

What is the significance of the BAR domain in membrane-associated proteins?

Accepted Answer

It senses and induces membrane curvature through its alpha-helical structure.

Question 5

Which of the following statements about FRAP (Fluorescence Recovery After Photobleaching) is correct?

Accepted Answer

It measures the lateral mobility of membrane proteins by monitoring fluorescence recovery.

Question 6

A protein is found to be tightly associated with the membrane due to a covalently attached lipid group. Which modification is most likely responsible?

Accepted Answer

Prenylation

Question 7

Which of the following best explains why prenylated proteins are energetically unfavorable in the cytoplasm?

Accepted Answer

The hydrophobic prenyl group is unstable in the aqueous cytoplasm.

Question 8

Which equation best represents the hydrolysis of pyrophosphate that drives headgroup addition in phospholipid synthesis?

Accepted Answer

$$PP_i + H_2O \rightarrow 2P_i$$

Question 9

A mutation disrupts the alpha-helical structure of a BAR domain protein. What is the most likely consequence?

Accepted Answer

The protein loses its ability to induce membrane curvature.

Question 10

Which of the following is a key difference between transmembrane and peripheral membrane proteins?

Accepted Answer

Transmembrane proteins span the lipid bilayer, while peripheral proteins associate with the membrane surface.

Question 11

In a FRAP experiment, what does a steep slope in the recovery curve indicate about the protein being studied?

Accepted Answer

The protein is highly mobile within the membrane.

Question 12

Which of the following best describes the function of GPI anchors in membrane proteins?

Accepted Answer

They tether proteins to the outer leaflet of the plasma membrane.

Question 13

Which of the following reactions is catalyzed by choline phosphotransferase in the synthesis of phosphatidylcholine?

Accepted Answer

$$CDP	ext{-}choline + diacylglycerol ightarrow phosphatidylcholine + CMP$$

Question 14

A patient has a genetic defect in the enzyme that adds headgroups to diacylglycerol. Which class of molecules would be most directly affected?

Accepted Answer

Phospholipids

Question 15

Which of the following best explains why the geometry of a protein binding site can influence membrane curvature?

Accepted Answer

The shape of the binding site can induce or stabilize curvature by matching the membrane's contour.

Membrane Phospholipid Synthesis and Protein-Membrane Interactions

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