Cell/Plasma Membranes

Question 1

Cell membrane function

Answer 1

Protects the cell organelles
Regulates the flow of matter between the cell and its environment
Semipermeable
1.Biological Barrier
2.Selective Filter

Question 2

Properties of cell membranes

Answer 2

All materials entering or exiting the cell must cross the cell membrane
Membranes can change according to each cells needs
Fluid and flexible
Called the ‘Fluid-Mosaic Model’

Question 3

Structure

Answer 3

Phospholipid bilayer
A double layer of phospholipids, a hydrophilic head and a hydrophobic tail
The head is in the outside and tail is in the inside

Question 4

Hydrophobic

Answer 4

Water repellent

Question 5

Hydrophilic

Answer 5

Able to mix well, dissolve or attract to water

Question 6

Function 1: Biological barrier

Answer 6

Prevents harmful substances from entering the cell (eg. salts, sugars, viruses, proteins, bacteria)
Surrounds each organelle to prevent unwanted chemical reactions

Question 7

Function 2: Selective filter

Answer 7

Semi permeable
Depends on:
1. Particle size - eg. oxygen and hydrogen are so small they can cross the membrane by slipping in between phospholipid molecules, but sugar and proteins are too big to cross directly
2. Membrane proteins - transport proteins can transport certain substances through the membrane. May also bind to specific chemicals based on their shape or electric charge