Module 2 Chapter 5 Lesson 1 - Cell Surface Membranes

Question 1

What do membranes do?

Answer 1

Keep the insides of organelles separate from cytoplasm.

Question 2

What are membranes important in?

Answer 2

Cell compartmentalisation.

Question 3

What are four features of the cell surface membrane?

Answer 3

Partially permeable barrier between a cell and it’s environment.
Controls what leaves and enters a cell.
Site of chemical reactions.
Site of cell communication (cell signalling)

Question 4

What does it mean by partially permeable?

Answer 4

Only some substances can pass through.

Question 5

What are two types of cell signalling?

Answer 5

Hormones
Nerve signalling

Question 6

Explain cell signalling.

Answer 6

Molecule is released from another cell is recognised by specific receptors and causes a response.

Question 7

What a receptors specific only to?

Answer 7

1 signalling molecule as they have a complimentary shape.

Question 8

How thick is they phospholipid bilayer?

Answer 8

7 nm

Question 9

What does the phospholipid bilayer act as a barrier against?

Answer 9

Large polar molecules

Question 10

What can pass through the phospholipid bilayer?

Answer 10

Fat soluble substances or very small molecules.

Question 11

Can the phospholipid bilayer move freely?

Answer 11

Nothing is holding them so it jiggles.

Question 12

Give 6 examples of what can pass through the phospholipid bilayer?

Answer 12

Steroids
H2O
CO2
Fats
Cholesterol
Fat soluble vitamins

Question 13

Why is the phospholipid bilayer jiggling useful?

Answer 13

Gives membrane fluidity.

Question 14

What is a feature of the part of the tail facing inward?

Answer 14

Hydrophobic

Question 15

What does cholesterol do to a membrane?

Answer 15

Stabilises it

Question 16

What is a feature of the part of the head facing outward?

Answer 16

Hydrophilic

Question 17

How does cholesterol regulate fluidity?

Answer 17

By binding to phospholipids

Question 18

What does cholesterol do to charged particles?

Answer 18

Reduces permeability.

Question 19

What does cholesterol do in the myelin sheath of a nerve cell?

Answer 19

Prevents it from leaking.

Question 20

What is a glycolipid?

Answer 20

Carbohydrate and a lipid

Question 21

What is a glycoprotein?

Answer 21

Carbohydrate and a protein

Question 22

How do glycolipids and glycolipids stabilise the membrane?

Answer 22

By forming hydrogen bonds with surrounding water molecules.

Question 23

What are glycolipids and glycolipids receptors for?

Answer 23

Cell signalling
Drugs
Hormones
Antibodies

Question 24

What do glycolipids and glycoproteins act as?

Answer 24

Antigens for self recognition and immune response.

Question 25

What do the intrinsic proteins span the width of?

Answer 25

Membrane

Question 26

What do intrinsic proteins transport?

Answer 26

Water soluble charged particles.

Question 27

What do channel proteins act as?

Answer 27

A passage way for water and charged substances to diffuse in and out of cells.

Question 28

What do carrier proteins do?

Answer 28

Change shape to move substances from one side of the membrane to the other. This can be down a concentration gradient (facilitated diffusion) or against (active transport)

Question 29

What are extrinsic proteins also known as?

Answer 29

Peripheral proteins

Question 30

Where are extrinsic proteins present in?

Answer 30

One side of the bilayer.

Question 31

What do extrinsic proteins have on their surface?

Answer 31

Hydrophilic R- groups on their surface

Question 32

Suggest how hydrogen peroxide could affect the plasma membrane. (2)

Answer 32

Oxidises cholesterol. Causes membrane to be more permeable.