Module 3: The Structure and Function of the Plasma Membrane

Question 1

What is plasma membrane?

Answer 1

• It i the outer boundary of the cell that separates it from the world. It is a thin, fragile structure.
• Need electron microscope to examine.

Question 2

Describe the plasma membrane structure?

Answer 2

• Found to be mostly composed of oil.
• The lipid bilayer accounted for the 2:1 ratio of lipid to cell surface area.

Question 3

What is the myelin sheath?

Answer 3

It acts as the electrical insulation for the nerve cell.

Question 4

What are membrane lipids?

Answer 4

They are amphipathic which contain both hydrophilic and hydrophobic regions.

Question 5

Describe phospholipids?

Answer 5

They are lipids with a phosphate group.

Question 6

Describe phosphoglycerides?

Answer 6

Phospholipids built on a glycerol backbone.

Question 7

Describe Shingolipids?

Answer 7

Derivatives of sphingosine, an
amino alcohol that contains a
long hydrocarbon chain.

Question 8

What are cermides?

Answer 8

• Are the basic structural units of all sphingolipids.
• A ceramide consist of sphingosine linked to a fatty acid (R) by its amino group.

Question 9

Function of the lipid bilayer?

Answer 9

Helps maintain the proper internal composition of a cell.

Question 10

Function of liposomes?

Answer 10

They are synthetic vesicles that act as vehicles to deliver drugs, DNA, RNA within the body.

Question 11

How are oligosaccharides attached to amino acids?

Answer 11

By two types of linkages: N-linkages and O-linkages.

Question 12

Function of glycolipid carbohydrates of the red blood cell?

Answer 12

Determines whether a person’s blood type is A, B, AB, or O.

Question 13

Types of blood types:

Answer 13

A: Enzyme adds N-acetylgalactosamine to the end of the chain.

B: Enzyme adds galactose to the chain terminus.

AB: Both enzymes present.

O: Lack enzymes capable of
attaching either terminal sugar.

Question 14

Function of integral membrane proteins?

Answer 14

They function as receptors that bind ligands, channels or transporters to move ions/solute across the membrane.

Question 15

What forces drive integral membrane proteins?

Answer 15

They are driven by van der waals forces between amino acids and lipids.

Question 16

What is peripheral membrane proteins?

Answer 16

• Peripheral proteins associate with the membrane by weak electrostatic bonds.
• Have a dynamic relationship with the membrane, being recruited or released as needed.

Question 17

What are lipid-anchored membrane proteins?

Answer 17

They are covalently bonded to a lipid group that reside within the membrane.

Question 18

What are the two types of lipid-anchor and the surface they are exposed to?

Answer 18

• Proteins located on the external face linked to the membrane via a GPI-porteins.
• Proteins located on the cytoplasmic side of the plasma membrane and anchored by one more long hydrocarbon chain in the inner membrane.

Question 19

What describes the physical state of membrane lipids?

Answer 19

By its fluidity or viscosity.

Question 20

How do cells respond to fluctuating temperatures?

Answer 20

By altering phospholipid composition.

Question 21

What catalyzes desaturation?

Answer 21

It is catalyzed by desaturases.

Question 22

Function of lipid rafts:

Answer 22

They provide a favorable environment for cell-surface receptors.

Question 23

What cell fusion?

Answer 23

It is a technique whereby two different types of cells, or cells
from two different species, can be fused to produce one cell.