2B-Cell membranes

Question 1

what is found in the phospholipid bilayer

Answer 1

phospholipids
cholesterol
proteins
protein channels
glycolipids
glycoprotein

Question 2

break down and explain the fluid mosaic

Answer 2

fluid: Phospholipid bilayer, flexible shape
mosaic: extrinsic and intrinsic proteins of different shapes sizes and shapes embedded

Question 3

the 5 types of movement across a membrane

Answer 3

-simple diffusion
-facilitated diffusion
-co-transport
-osmosis
-active transport

Question 4

what is used in active transport

Answer 4

ATP as an energy source

Question 5

what is diffusions 2 marks

Answer 5

the net movement of particles from an area of higher concentration to an area of lower concentration ( down the concentration gradient)

Question 6

what does facilitated diffusion require

Answer 6

carrier and channel proteins

Question 7

what substances require facilitated diffusion and why

Answer 7

charged particles such as ions or polar molecules because the bilayer is hydrophobic

molecules that are too large cannot pass via simple diffusion process

Question 8

how do carrier proteins work during
facilitated diffusion
4 point

Answer 8

-move large molecules across membranes
-large molecule attaches to the carrier protein
-protein changes shape
-this releases the molecule on the opposite side of the membrane

Question 9

how do channel proteins work during facilitated diffusion

Answer 9

channel proteins form pores in the membrane and allow for charged particles to diffuse down the concentration gradient

Question 10

3 factors effecting rate of simple diffusion

Answer 10

-concentration gradient (higher the faster)
-thickness of exchange surface
-surface area

Question 11

2 factors effecting rate of facilitated diffusion

Answer 11

-concentration gradient
number of channel or carrier proteins

Question 12

what has the highest water potential

Answer 12

pure water

Question 13

3 factors effecting rate of osmosis

Answer 13

water potential gradient (higher the better)
thickness of exchange surface
surface area of exchange surface

Question 14

what is water potential

Answer 14

potential of water molecules to diffuse out or into a solution
(more water the more likely it is to move)

Question 15

which protein is used in active transport

Answer 15

carrier proteins

Question 16

difference between active transport and facilitated diffusion

Answer 16

-active transport moves against the concentration gradient

-active transport requires energy (ATP)

Question 17

how do co-transporters work as carrier proteins

Answer 17

-they bind two molecules together
-concentration gradient of one of the molecules is used to move the other against its concentration gradient

Question 18

3 factors effecting rate of active transport

Answer 18

speed of individual carrier proteins
number of carrier proteins present
rate of respiration / availability of ATP

Question 19

describe how glucose enters the blood (6mark)

Answer 19

.sodium ions are actively transported out of the ileum epithelial cells, into the blood, by the sodium-potassium pump, there is now a higher concentration of Na ions in the lumen of the ileum than inside the cell

.this causes sodium ions to diffuse from the lumen of the ileum into the epithelial cell, down their concentration gradient, they do this via sodium-glucose co-transporter

.The co-transporter carries glucose into the cell with the sodium, concentration of glucose inside the cell increases

.glucose diffuses out of the cell into the blood through protein channel in facilitated diffusion

Question 20

the role of cholesterol in the bilayer

Answer 20

connect phospholipids and reduces fluidity to make structure more stable (keeps membrane rigid)

Question 21

role glycolipids

Answer 21

cell signalling and cell recognition