UNIT 2 (topic 3) phospholipid bilayer

Question 1

what is the structure of a phospholipid

Answer 1

phosphate group, glycerol and 2 fatty acids

Question 2

what are the properties of the fatty acid tails

Answer 2

hydrophobic, non-polar, lipid-soluble, small

Question 3

what is the purpose of the glycerol

Answer 3

acts as a backbone to connect the phosphate group and the fatty acids

Question 4

why is the phospholipid bilayer known as the ‘fluid-mosaic model’

Answer 4

fluid - membrane is flexible
mosaic - mixture of phospholipids and proteins

Question 5

what is the function of the integral protein

Answer 5

spans the whole phospholipid bilayer
channel proteins - allows soluble ions to diffuse through the membrane
carrier proteins - binds to ions then changes shape to move them across the membrane

Question 6

what is the function of peripheral proteins

Answer 6

surface of the bilayer for support and act as a cell receptor for other molecules

Question 7

what is the function of a glycoprotein

Answer 7

carbohydrate chain attached to a peripheral protein - acts as a cell receptor for specific molecules (hormones and transmitters)

Question 8

what is the function of a phospholipid bilayer

Answer 8

allows lipid soluble, non-polar molecules to leave and enter the cell

Question 9

function of cholesterol

Answer 9

found in-between fatty acid tails
- reduces movement from fatty acids by pulling on them
- adds strength to membrane
- very hydrophobic - reduces water loss