3D

Question 1

What is the composition of a membrane bilayer?

Answer 1

A membrane bilayer consists of phospholipids and proteins.

Question 2

What are the dynamics and organization of membrane bilayers?

Answer 2

Membrane bilayers are dynamic structures that can change shape and organization.

Question 3

What are membrane proteins?

Answer 3

Membrane proteins are proteins that are embedded in or associated with the lipid bilayer of a membrane.

Question 4

How can the diffusion of membrane proteins be measured?

Answer 4

Diffusion can be measured using techniques like FRAP (Fluorescence Recovery After Photobleaching).

Question 5

What is lateral diffusion of membrane proteins?

Answer 5

Lateral diffusion refers to the movement of proteins within the plane of the membrane.

Question 6

What is the characteristic of _______ diffusion in membrane proteins?

Answer 6

Free or unrestrained diffusion.

Question 7

What is the characteristic of _______ diffusion in membrane proteins?

Answer 7

No or negligible diffusion.

Question 8

What is the characteristic of _______ diffusion in membrane proteins?

Answer 8

Restricted or partial diffusion.

Question 9

Provide an example of limited diffusion in cells.

Answer 9

Polarized epithelial cells.

Question 10

What separates the apical and basal membranes in epithelial cells?

Answer 10

Tight junctions.

Question 11

What is the role of the tight junction?

Answer 11

It separates the apical and basal membranes in epithelial cells.

Question 12

Which Nobel Prize winner is associated with tight junction research?

Answer 12

George Palade.

Question 13

What are the functions of the apical and basal membranes?

Answer 13

They have distinct compositions and functions despite being contiguous.

Question 14

What is the function of the NA-K ATPase?

Answer 14

It is localized to the basolateral membrane.

Question 15

What is the role of aquaporins?

Answer 15

They function as water transporters in the apical membrane.

Question 16

What are mechanisms that restrict membrane protein movement?

Answer 16

Self-assembly into complexes, tethering to the extracellular matrix, tethering to the cytoskeleton, and interacting with proteins on other cells.

Question 17

What structure gives red blood cells their biconcave shape?

Answer 17

Membrane protein interactions with the cortical cytoskeleton.

Question 18

What is spectrin?

Answer 18

A protein that forms a mesh-like structure under the plasma membrane.

Question 19

What are two integral membrane proteins that bind spectrin?

Answer 19

• Glycophorin
• Band 3

Question 20

What does the spectrin cortical cytoskeleton do?

Answer 20

It interacts with membrane proteins and provides shape and structure to red blood cells.

Question 21

What is the function of the junctional complex in red blood cells?

Answer 21

It cross-links spectrin filaments and connects them to the membrane.

Question 22

What is the significance of restricted protein diffusion?

Answer 22

It is critical for the function of some cells, such as epithelial and sperm cells.

Question 23

True or False: Most membrane proteins are free to diffuse throughout the entire cell membrane.

Answer 23

False.

Question 24

What is indicated by the actual path of a single protein molecule in a membrane?

Answer 24

It indicates that the protein spends significant time diffusing within a corral.

Question 25

What are the dimensions of corrals that restrict protein diffusion?

Answer 25

200-400 nm.

Question 26

How does restricted diffusion occur in epithelial or endothelial cell layers?

Answer 26

Proteins are restricted from moving between apical and basolateral membranes.

Question 27

What is the importance of studying the movement of individual protein molecules?

Answer 27

It reveals how molecules are controlled inside the cell.