Unit 1 - AOS1 - Plasma membrane

Question 1

Function of Plasma Membrane

Answer 1

Controls the passage and movement of materials into and out of a cell.

Question 2

2 physical characteristics of the plasma membrane

Answer 2

• 1 bilayers of phospholipids
• is Semipermeable (only some materials may enter/exit)

Question 3

Materials that can easily pass through the plasma membrane?

Answer 3

Small, uncharged molecule
e.g carbon dioxide, oxygen

Question 4

Material that are Difficult/unable to pass through the plasma membrane?

Answer 4

Large molecule
Ions (charged)
e.g chlorine, phosphate

Question 5

What are phospholipids made of?

Answer 5

Polar head (both positive and negative)
1. Phosphate group (positive)
2. Glyceral (negative)

Nonpolar tails
1. Two chains of fatty acids

• Arrangement: polar heads are on outside & nonpolar tails are on inside

Question 6

Hydrophilic definition & what part of phospholipid carries this trait?

Answer 6

Definition: It is attracted to/seeks out water

• The polar head of the phospholipid is hydrophilic

Question 7

Hydrophobic definition & what part of phospholipid carries this trait?

Answer 7

Definition: Not attracted to water
- The nonpolar tails of the phospholipid are hydrophobic

Question 8

Meaning of the Fluid Mosaic Model in relation to the plasma membrane?

Answer 8

Fluid = in motion (not static)
Mosaic = many parts/complex

Question 9

Cholesterol function & characteristics

Answer 9

• Prevents phospholipids from separating to far (keeps the cell membrane compact & bound together)
• Flexibility

Question 10

Protein Channel Function & characteristics

Answer 10

Allows certain objects to pass through
Why?:
- Some materials can’t pass through the phospholipid bilayer
- Allows molecule that are larger or charged to pass through e.g. glucose

Question 11

Carbohydrate function & characteristics

Answer 11

• Identification/recognition of cell (sometimes attached to lipids or proteins)
• “receptor” for our immune system so it knows what cells to target

Question 12

Cytoskeleton function & characteristics

Answer 12

• Protein threads (microtubules, microfilaments, intermediate
  filaments)
• internal support
• Acts as a pathway for molecule transport (exit and enter using protein threads)

Question 13

What do the phospholipids create?

Answer 13

Phospholipid bi-layer

Question 14

4 functions of the phospholipid bi-layer (D.I.R.T)

Answer 14

1. is an active and selective boundary (not-stationary)
2. Denotes cell identity
3. Receives external signals
4. transports materials