Chapter 10: Cell Membranes

Question 1

What is the approximate width of a typical phospholipid bilayer?

Answer 1

~5 nm

Question 2

This type of study can be used to easily measure diffusion rates, but cannot measure active transport

Answer 2

permeability studies

Question 3

This steroid maintains fluidity, permeability, and structure of the lipid bilayer; also lowers freezing point

Answer 3

cholesterol

Question 4

What lipids are found in the outside layer of the phospholipid membrane?

Answer 4

1. phosphatidylcholine
2. sphingomyelin
3. glycolipids

Question 5

what lipids are found in the inner layer of the phospholipid membrane?

Answer 5

1. phosphatidylethanolamine
2. phosphatidylserine

Question 6

Newly formed phospholipids are inserted ONLY on what layer of the phospholipid membrane?

Answer 6

the inner layer

Question 7

What membrane lipid is negatively charged and reacts predominantly with positive molecules?

Answer 7

phosphatidylserine

Question 8

What are 2 functional benefits of maintaining intentional phospholipid bilayer asymmetry?

Answer 8

1. useable gradients
2. association with peripheral/anchoring proteins

Question 9

intercellular regions that aid in cell formation of an efficient permeability layer

Answer 9

tight junctions

Question 10

In a typical cell, what is the protein:phospholipid ratio?

Answer 10

1:50

Question 11

In a nerve cell, what is the protein:phospholipid ratio?

Answer 11

1:25

Question 12

In a mitochondrial membrane, what is the protein:phospholipid ratio?

Answer 12

1:75

Question 13

about what percentage of the genome is dedicated to encoding for integral membrane proteins

Answer 13

~30%

Question 14

Membrane-spanning protein domains that typically adopt an alpha-helical structure and differ in length depending on the organelles they are designated for

Answer 14

TMD (Transmembrane domain)

Question 15

What do intergral protein additions do to the phospholipid membrane?

Answer 15

distorts membrane width

Question 16

What is one method organelle membranes use to identify what integral proteins fit where?

Answer 16

TMD length/width

Question 17

What organelle tends to have the thinnest TMD?

Answer 17

Golgi apparatus

Question 18

What are three examples of detergents?

Answer 18

1. SDS
2. Triton X
3. B-octylglucoside

Question 19

These substances can pull out integral membrane proteins by enveloping them in protein-lipid complexes

Answer 19

detergents

Question 20

This describes the value at which the solution property of a molecule shows an abrupt change; At this concentration, surface active ions or molecules in solution associate to form larger units

Answer 20

CMC (Critical Micelle Concentration)

Question 21

This is a bacterial, light-sensing protein proton pump that was one of the first of its kind to be identified

Answer 21

Bacterial rhodopsin

Question 22

What molecules does the outside of the cell membrane consist of?

Answer 22

glycoproteins, lipids, proteoglycans

Question 23

What side of the cell membrane has a large net negative charge?

Answer 23

extracellular space

Question 24

What can be used to measure integral protein/ion levels or differences after isolation from the membrane using detergents?

Answer 24

ion probes

Question 25

The addition of phospholipids to isolated integral membrane protein (rinsed of detergent) creates what?

Answer 25

vesicles to measure active transport