Cell membrane

Question 1

What is the cell membrane?

Answer 1

Phospholipids form the basis of the membrane and surrounding organelles

Question 2

What is a phospholipid composed of?

Answer 2

Hydrophilic glycerol heads which attract water and face outwards towards the water, Hydrophobic fatty acid tails which repel water and face inwards away from water. Also a phosphate group

Question 3

Role of hydrophilic glycerol heads

Answer 3

Make contact with watery cytoplasm and extra cellular fluids causing a bilayer

Question 4

Purpose of cell membrane

Answer 4

Controls entry and exit of molecules which is selectively permeable

Question 5

Cell membrane components

Answer 5

Proteins, glycoproteins, phospholipids, carbohydrates and cholesterol

Question 6

Why is the cell membrane described as ‘fluid’?

Answer 6

Molecules are constantly moving around the bilayer (proteins and lipids) relative to each other

Question 7

Why is the cell membrane described as ‘mosaic’?

Answer 7

Proteins molecules are unevenly distributed throughout the structures

Question 8

What determines the cell membrane permeability?

Answer 8

The type and distribution of transport proteins and phospholipid molecules

Question 9

Function of a channel protein:

Answer 9

•Allow passage of ions/polar/charged molecules because the phospholipid has a charge itself
•Specific tertiary structure and make hydrophilic tunnels
•Selective -> Allow only one type of a few closely related