2.1.5 Biological membranes Flashcards Preview

OCR Biology A level New Spec > 2.1.5 Biological membranes > Flashcards

Flashcards in 2.1.5 Biological membranes Deck (31):
1

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

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

2

what is a partially permeable barrier

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

3

list the role cell membranes within cells/ around organelles

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

4

what does the fluid mosaic model propose

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

5

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

diagram

6

what are the roles of phospholipids

1

7

what r the roles of cholesterol

2

8

what r the roles of glycolipids

3

9

what r the roles of proteins

4

10

what r the roles of glycoproteins

5

11

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

6

12

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

7

13

what is a passive process vs an active process

8

14

define diffusion

9

15

describe the process of simple diffusion

1

16

how do you maintain a concentration gradient

1

17

what factors affect the rate of simple diffusion

1

18

define facilitated diffusion

1

19

describe the process of facilitated diffusion

1

20

what is the solute

1

21

what is the solvent

f

22

define diffusion

f

23

describe the process of diffusion

f

24

what is water potential

f

25

what are the units of water potential

f

26

what do the units of water potential indicate

f

27

what happens when the water potential is high in plant cells

f

28

what happens when the water po is low in plant cells

f

29

what happens when the water potential is high in animal cells

f

30

what happens when the water po is low in animal cells

f

31

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

f