membranes

Question 1

width of membrane

Answer 1

7-10 nm

Question 2

what is cell membrane made up of

Answer 2

• phospholipid bilayer
• intrinsic and extrinsic proteins
• glycoproteins
• cholesterol

Question 3

what did Gortner and Grendel do?

Answer 3

• study structure of cell membrane in different mammals
• total SA of red blood cells measured in sample, compared to SA formed by single lipid layer extracted
• lipid layer floated on water
• single layer double total surface area, phospholipids fold over each other

Question 4

what can get through phospholipid bilayer?

Answer 4

small, uncharged and lipid soluble molecules

Question 5

why is it selectively permeable?

Answer 5

non-polar tails repel water soluble, large charged molecules

Question 6

channel proteins

Answer 6

intrinsic - pores lined with polar groups, allows water soluble substances to pass through

Question 7

carrier proteins

Answer 7

intrinsic - allows large polar molecules to pass through, molecules bind to protein and is released on other side of the membrane

Question 8

what do extrinsic proteins do?

Answer 8

cell recognition
form receptors
cell signalling
anchor cell components

Question 9

what does cholesterol do?

Answer 9

associates with the kinked tails of unsaturated fatty acids
- allows phospholipids to pack closely together and behave like a fluid (maintains membrane fluidity)

Question 10

what is the fluid mosaic model?

Answer 10

Singer and nicholson = fluid mosaic structure
fluid= all components can independently move
mosaic = proteins float in phospholipids, no fixed arrangement or pattern