Module 4 Membranes

Question 1

Plasma Membrane

Answer 1

1. Protects cell from outside environment, Homeostasis
2. Controls cell’s cytoplasmic contents
3. Senses the environment

Question 2

Plasma Membrane binds to

Answer 2

Cytoskeleton and Extracellular Matric (ECM)
* Help maintain cell’s shape

Question 3

Plasma membrane is selectively permeable.

Question 4

Proposed models for structural makeup of membrane

Answer 4

1. Davson-Danielli Model
2. Fluid Mosaic Model - Sanger and Nicholson (1972)

Question 5

Phospholipids in membrane are in CONSTANT movement

Answer 5

Hence the “Fluid” in Fluid-Mosaic Model

Question 6

Cholesterol in phospholipids

Answer 6

Cholesterol intercalates between phospholipids helps maintain structural integrity of the membrane. More rigid than phospholipids.

Question 7

Membrane in cold temperature:

Answer 7

Membrane becomes more fluid

Question 8

Membrane in warm temperature:

Answer 8

Membrane becomes less fluid

Question 9

Causes of changes in biochemistry of membranes

Answer 9

Increase in number of membrane proteins, amount of unsaturated fatty acids, and amount of cholesterol

Question 10

Diversity of proteins in membrane

Answer 10

1. Surface proteins
2. Transmembrane proteins: Controls what comes in and out; signal molecules; can detect things outside of the cell and change structure

Question 11

Different functions of membrane proteins

Answer 11

1. Anchor proteins: Interact with microfillaments and give integrity to cell
2. Enzyme proteins: Anchored to membrane; facilitate changes and convert molecules
3. .

Question 12

Issues with moving things through membrane

Answer 12

1. Diffusion: molecules naturally move down concentration gradient
2. Sometimes going against gradient is necessary; must put in more work