Chapter 4 Transport Across Cell Membrane

Question 1

How are phospholipids laid out in the cell surface membrane?

Answer 1

Hydrophilic head of phospholipids layer point to the out side of membrane
Hydrophobic tails point into centre of cell membrane

Question 2

Functions of phospholipids?

Answer 2

Allow lipid soluble substances enter and leave cell
Prevent water soluble substances entering/leaving cells
Make membrane flexible

Question 3

Why do some proteins never extend over the bilayer?

Answer 3

Act as either mechanical support to membrane or alongside glycolipids as cell receptors for molecules

Question 4

When di some proteins extend completely over bilayer?

Answer 4

Protein channels that form water filled tubes

Carrier proteins

Question 5

What are protein channels?

Answer 5

Water filled tubes allow water soluble ions to diffuse across membrane

Question 6

What are protein carriers?

Answer 6

Bind to ions/molecules then change shape in order to move molecules across membrane

Question 7

Function of proteins in membrane

Answer 7

Provide support
Act as channels
Act as receptors

Question 8

Functions of cholesterol

Answer 8

Reduce lateral movement of phospy

Make membrane less fluid

Question 9

Function of glycomipids

Answer 9

Act as recognition site
Help maintain stability of membrane
Helps cell to attach one another

Question 10

What is ment by passive

Answer 10

Energy comes from natural inbuilt motion of particles rather then external

Question 11

What is facilitated diffusion?

Answer 11

Only occurs between different concentration of same substances
Diffusion is facilitated by channels and carriers

Question 12

What are protein channels

Answer 12

Water filled hydrophilic channels across membrane

Allow water soluble molecules through

Question 13

What are carrier proteins ?

Answer 13

Molecule specific to protein is present it binds with protein
Causes change shape so molecules are released

Question 14

What is water potential ?

Answer 14

Pressure created by water molecules

Question 15

What is water potential of pire water?

Answer 15

0

Question 16

How to find water potential of cell?

Answer 16

Place them in series of solutions of different water potential
Where this is no net gain/loss water potential is the same

Question 17

Factors affecting rate of osmosis?

Answer 17

Higher the water potential m, the faster the rate of reaction
Thickness of exchange surface
The larger the surface area the faster

Question 18

In active transport what is ATP used for?

Answer 18

Dorectly move molecules

Individually move molecules using concentration

Question 19

Why is active transport not considered passive?

Answer 19

Metabolic energy required
Substance move againts c gradient
I

Question 20

What is the sodium potassium pump?

Answer 20

Sodium ions actively removed from cell while potassium ions are actively taken in from surroundings

Question 21

What does epithelial cells lining ileum contain?

Answer 21

Microvilli

Question 22

How to increase transport across membrane ?

Answer 22

Increase number of protein channels and carriers