Module 2 - Membranes

Question 1

How can molecules move across membranes

Answer 1

Diffusion
Osmosis
Active transport

Question 2

What are the molecules in the structure of a cell membrane

Answer 2

Phospholipid
Cholesterol 
Glycoproteins
Glycolipid
Protein channel
Proteins

Question 3

Describe a phospholipid molecule

Answer 3

Head is hydrophilic

Tail is hydrophobic

Question 4

What is the role of the phospholipid bilayer

Answer 4

The tails on the phospholipid join together to prevent water soluble substances from entering .

Question 5

What is the role of cholesterol in a cell membrane

Answer 5

Fits itself in between the phospholipids causing they to pack more closely together making the membrane more rigid

Question 6

What is the role of proteins in a cell membrane

Answer 6

1) form channels in the membrane which allow small particles through
2) act as receptors for cell signalling

Question 7

What is the role of glycolipids/glycoproteins

Answer 7

To stabilise the membrane by forming hydrogen bonds with surrounding water molecules

Act as receptors for cell signalling

Question 8

What is cell signalling

Answer 8

A way of communicating for cells

Question 9

How does cell signalling occur

Answer 9

A messenger molecule is released from one molecule
The molecule travels to another cell
The molecule binds to the receptor on another cell

Question 10

Explain glucagon in terms of cell signalling

Answer 10

Glucagon is released when there is not enough glucose in the blood
Binds to receptors on liver cells so that liver cells break down their glycogen into glucose

Question 11

What is osmosis

Answer 11

Diffusion of water molecules across a partially permeable membrane down a water potential gradient gradient