Cell Membrane

Question 1

Fluid mosaic model

Answer 1

bilayer of phospholipids with proteins and cholesterol interspersed throughout the structure
“fluid” as phospholipids are constantly moving around
“mosaic” as protein molecules are scattered throughout the phospholipids like tiles in a mosaic

Question 2

Phospholipids

Answer 2

hydrophillic head faces the intracellular/extracelluar fluid
two hydrophobic tails which point towards each other
form a barrier to anything not lipid soluble

Question 3

Glycoprotein

Answer 3

proteins with sugar molecules attached
act as recognition sites and antigens

Question 4

Glycolipids

Answer 4

phospholipids with sugar molecules attached act
recognition sites and antigens
increase membrane stability by forming hydrogen bonds

Question 5

Cholesterol

Answer 5

lipid which slots in between the phospholipid tails, pushing them closer together
Regulates stability and fluidity of the plasma membrane

Question 6

Intrinsic proteins

Answer 6

proteins that span both bilayers of the plasma membrane
Act as channels or carrier proteins to transport water soluble molecules

Question 7

Extrinsic proteins

Answer 7

found on surface of plasma membrane
Function as enzymes and catalyse chemical reactions inside cell

Question 8

Simple diffusion

Answer 8

Movement of molecules down conc gradient
pass directly through the phospholipid bilayer
passive process
Rate depends on : conc gradient, thickness of the exchange surface, SA

Question 9

Facilitated diffusion

Answer 9

Movement of molecules down conc gradient
Carrier proteins or channel protein helps
Passive process
Rate depends on: conc gradient, no of channel/carrier proteins

Question 10

Osmosis

Answer 10

Movement of water molecules down conc gradient across partially permeable membrane
Passive process Rate depends
Water potential: more solute, lower potential, same water potential = isotonic
Rate depends on: water potential gradient, SA, thickness of exchange surface

Question 11

Active transport