Cell Membrane

Question 1

What are the main components of a cell membrane?

Answer 1

Phospholipids

Question 2

What is the structure of a phospholipid?

Answer 2

phosphate head

two fatty acid tails

Question 3

key features of phosphate heads -

Answer 3

• polar
• hydrophilic
• can interact with water

Question 4

Key features of fatty acid tails -

Answer 4

• non polar
• hydrophobic
• repel water

Question 5

How are phospholipids in a cell membrane arranged?

Answer 5

In a bilayer

Question 6

Why is a bilayer ideal?

Answer 6

It forms a compartment that can be filled with aqueous cytoplasm. The cell can also be filled with aqueous tissue fluid, meaning that he phospholipids can move around allowing the call membrane to change shape.

Question 7

What do cell membranes contain?

Answer 7

• proteins
• glycoproteins (proteins with carbohydrate chains attached)
• glycolipids (lipids with carbohydrate chains attached)
• cholesterol

Question 8

Explain fully why the phospholipids in the cell surface from a bilayer (4 marks)

Answer 8

• Hydrophilic phosphate head interacts with water.
• Hydrophobic fatty acid tails repel water
• Water on both sides of the membrane, so the phospholipids will orient themselves.

Question 9

function of proteins

Answer 9

• enzymes

- carrier and channel proteins are involved in the transport of substances into and out of the cell.

Question 10

function of glycoproteins and glycolipids

Answer 10

• cell to cell recognition

- receptors

Question 11

function of cholesterol

Answer 11

• makes the membrane more rigid

- determines fluidity

Question 12

Suggest why this arrangement is known as the fluid mosaic model (2 marks)

Answer 12

• phospholipids can move or proteins can move around

- proteins are randomly inserted in plasma membrane - like mosaic tiles.