cell membrane

Question 1

S: phospholipid bilayer

Answer 1

amphipathic, arrange to form bilayer with phosphate heads interacting with aqueous medium and hydrocarbon tails forming hydrophobic core in aqueous environment

Question 2

F: phospholipid bilayer

Answer 2

1. regulates movement of substances in and out of cell by acting as barrier to charged ions and polar and large molecules
2. allows compartmentalization in cell
3. acts as boundary

Question 3

S: Cholesterol

Answer 3

4-ring structure lipid, in between phospholipid molecules and is slightly amphipathic
(-OH group aligns with phosphate heads and rest with hydrophobic core)

Question 4

F: Cholesterol

Answer 4

1. regulates membrane fluidity
   - prevent overly fluid at warmer temps, by restricting phospholipid movement
   - prevent overly firm at lower temps, by preventing close packing of phospholipids and thus solidification
2. anchor proteins in membrane

Question 5

F: Proteins

Answer 5

1. Channel proteins - hydrophilic channel for direct diffusion of ions or molecules across mem from high to low conc
2. Carrier proteins - bind solute on one side of mem and protein undergoes conformational change that allows access to opposite side of membrane OR pumps that use ATP to move solutes against conc gradient
3. enzymes
4. receptor proteins
5. stabilise membrane structure

Question 6

glycolipids and glycoproteins

Answer 6

1. function as markers/recognition sites in cell-cell recognition and adhesion
2. function as receptors