Membranes

Question 1

roles of membranes in cells

Answer 1

• controls what enters and exits the cells
• separating organelle contents from cytoplasm
• pass electrical impulses
• cell signalling
• cell recognition
• Hold components of metabolic pathways in place

Question 2

structure of plasma membrane

Answer 2

made of double layer of phospholipids
- large and charged molecules cannot pass through the phospholipid bilayer e.g. glucose, ions (NA+, CL-)
- can pass = co2 or 02
hydrophilic head and hydrophobic tail

Question 3

fluid model mosaic

Question 4

effect of saturated fats on membrane fluidity -o-
effect of unsaturated fats on membrane fluidity -o-

Answer 4

Membranes are less fluid

bends are less tight= membranes are more fluid

Question 5

How cholesterol affects membrane fluidity
If it too hot or cold how does cholesterol react ?

Answer 5

cholesterol affect heart health and associated with heart attacks

Too hot = cholesterol interacts with fatty acid, stopping them from pulling apart. Membrane doesn’t become too fluid

Too cold = cholesterol stops fatty acid tails from packing too tightly - membranes remains fluid

Question 6

endothelial cells in blood vessels
- primary function
- roles

Answer 6

the primary function of endothelial cells is to form a smooth non stick surface that allows blood to flow freely

they play a crucial role in
- regulating blood vessel tone which affects blood pressure ( Vasodilation lumen gets wider and vasoconstriction lumen gets narrower )
- immune response
- the exchange of substances between the blood and surrounding tissues

Question 7

Define cell signalling

Answer 7

A molecule from one cell binds to another cell leading to a response .
Insulin ( from pancreas ) -> receptors ( muscle and liver)
receptors are usually glycoproteins

Question 8

what are antigens ?

Answer 8

usually glycolipids or glycoproteins