Cell Surface Membrane

Question 1

Define cell surface membrane

Answer 1

surrounds cells and acts as a boundary between cell cytoplasm and the environment

Question 2

Describe the features of the cell surface membrane

Answer 2

Allows different conditions to be established in and outside of the cell

selectively permeable so controls movement of substances in and out

cell recognition and signalling

Question 3

What is the cell surface membrane made out of?

Answer 3

phospholipid bilayer

Question 4

Describe the phospholipid bilayer and its function

Answer 4

Fatty acid tails= hydrophobic and point into the centre
hydrophilic heads point to the outside

Function= allow lipid-soluble substances to enter and leave. Not water soluble

Question 5

What substances can and cannot pass the cell surface membrane?

Answer 5

can= nonpolar,water.alcohol,gases

can’t=ions and polar molecules

Question 6

What is the name of the model of the cell surface membrane and why?

Answer 6

Fluid-Mosaic Model
fluid= phospholipid molecules can move relative to one another
mosaic= proteins and phospholipids are different sized

Question 7

What are the two types of proteins in the cell surface membrane?

Answer 7

Intrinsic= Embedded, interacts with the outside and inside
Extrinsic= Outside membrane interacts with the outside only

Question 8

List the functions of proteins in the cell surface membrane

Answer 8

Provides structural support
channel transport water-soluble proteins
active transport across carrier proteins
cell surface receptors for identifying cells
helps cells adhere together
act as receptors

Question 9

Name the parts of the cell surface membrane

Answer 9

Phospholipid bilayer
Proteins
Cholesterol
Glycoprotein
Glycolipid

Question 10

What is the function of the cholesterol ?

Answer 10

Adds strength by pulling tails together
Prevents loss of water as it is very hydrophobic
Reduce lateral movement of other molecules
make membrane less fluid at high temperatures

Question 11

What is the function of glycoproteins?

Answer 11

acts as a recognition site
helps cells bind to cells to form tissues
allows cells to recognize one another
cell surface membrane receptor for hormones and neurotransmitter

Question 12

What is the function of glycolipids?

Answer 12

cell surface receptor for chemicals
acts as a recognition site
maintains stability of the membrane forms tissues

Question 13

Why can’t some molecules not pass through the cell surface membrane

Answer 13

not soluble in lipids
too large to pass through channel
same charge as channel so is repelled
polar so struggle passing non-polar tails