2 Cell Membranes

Question 1

Why do hydrophobic tails face inwards?

Answer 1

Minimise contact with water

Question 2

What is the most basic class of phospholipid and its structure?

Answer 2

Phosphatidylcholines

CHOLINE
PHOSPHATE
GLYCEROL

TAILS

Question 3

Define symporters and give and example.

Answer 3

Sugars eg glucose and aa can be dragged into cell (against their own conc gradient) with Na+ as it moves down its concentration gradient

Called cotransport

Question 4

Define antiporters and give an example.

Answer 4

Molecules move (against their own conc gradient) in opposite direction to Na+ eg. H+

Question 5

Protein functions on membrane

Answer 5

Signalling 
Receptors 
Transporters
Adhesion 
E- carrier

Question 6

What does Na K pump do?

Answer 6

3Na out and 2K in (Na move in naturally)

Negative intracellular potential

Question 7

How can external chemical signals be sensed in the interior of a cell?

Answer 7

Primary messenger eg hormone is detected by receptor which causes production of secondary messenger within cell