2.1.5 Biological membranes

Question 1

list the role cell membranes at the surface of cells (cell surface membranes/plasma membranes)

Answer 1

1. separates cells components from its external environ
2. regulates transport of materials in and out of cell BC ACTS AS PARTIALLY PERMEABLE BARRIER!!!
3. contains antigens so immune system does not recognise it asa foreign object
4. contains receptors for chemical signalling - site of cell communication/signalling
5. may b site of chemical reactions

Question 2

what is a partially permeable barrier

Answer 2

do not let all types of molecule pass thru and controls which subs enter and exit the cell

Question 3

list the role cell membranes within cells/ around organelles

Answer 3

1. compartmentalises the cells contents
2. acts as a partially permeable barrier between organelle and cyto and hence controls which substances go in and out of organelle e.g. lysosomes contain digestive enzymes
3. can form vesicles to transport subs between diff parts of cell e.g. proteins r transported using vesicles from REM to golgi during protein synthesis
4. membranes within organelles act as barriers between membrane contents and rest of organelle e.g. thylakoid membranes in chloroplasts that house chlorophyll, also it is where some reactions of photosynthesis occur => (link)
5. can b site of chemical reactions e.g. inner membrane of mitochondria (cristae) contains enzymes for respiration - it has large SA making respiration more efficient

Question 4

what does the fluid mosaic model propose

Answer 4

it proposes that the fabric of the membrane consists of a phospholipid bilayer (bilayer)

• with proteins floating in it, making a mosaic pattern
• the lipid molecules can change places w each other + some proteins can move hence giving it fluidity

Question 5

what does is fluid mosaic model of membrane structure (what does it contain) + draw

Answer 5

diagram

Question 6

what are the roles of phospholipids

Answer 6

1

Question 7

what r the roles of cholesterol

Answer 7

2

Question 8

what r the roles of glycolipids

Answer 8

3

Question 9

what r the roles of proteins

Answer 9

4

Question 10

what r the roles of glycoproteins

Answer 10

5

Question 11

what r the roles of membrane-bound receptors as sites where hormones and drugs can bind

Answer 11

6

Question 12

give an example of a cell membrane that has a diff composition to the fluid mosaic model

Answer 12

7

Question 13

what is a passive process vs an active process

Answer 13

8

Question 14

define diffusion

Answer 14

9

Question 15

describe the process of simple diffusion

Answer 15

1

Question 16

how do you maintain a concentration gradient

Answer 16

1

Question 17

what factors affect the rate of simple diffusion

Answer 17

1

Question 18

define facilitated diffusion

Answer 18

1

Question 19

describe the process of facilitated diffusion

Answer 19

1

Question 20

what is the solute

Answer 20

1

Question 21

what is the solvent

Answer 21

f

Question 22

define diffusion

Answer 22

f

Question 23

describe the process of diffusion

Answer 23

f

Question 24

what is water potential

Answer 24

f

Question 25

what are the units of water potential

Answer 25

f

Question 26

what do the units of water potential indicate

Answer 26

f

Question 27

what happens when the water potential is high in plant cells

Answer 27

f

Question 28

what happens when the water po is low in plant cells

Answer 28

f

Question 29

what happens when the water potential is high in animal cells

Answer 29

f

Question 30

what happens when the water po is low in animal cells

Answer 30

f

Question 31

what do you call tissue when the cells in the tissue have been plasmolysed

Answer 31

f