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AQA A-Level Biology Year 1 > Membranes > Flashcards

Flashcards in Membranes Deck (41)
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1

What is the role is cholesterol ?

adds strength

2

What is the fluid - mosaic model?

the structure of membrane

3

what is an intrinsic protein ?

spans the whole membrane

4

What is the arrangement of phospholipids

phospholipid bilayer

5

What is the hydrophobic region?

fatty acid tails

6

What is the hydrophilic region?

the phosphate head

7

what is the majority lipid in a membrane

phospholipid

8

what is an extrinsic protein?

loosely bound to outside of a membrane

9

What is a passive process

does not require ATP

10

What is osmosis?

movement of water down water potential gradient

11

what is a glycoprotein?

a protein with a carbohydrate attached

12

what is a glycolipid?

a lipid with a carbohydrate attached

13

What is a carrier protein?

changes shape to transport substances across membrane

14

What is the role of proteins in membranes

enzymes
receptors
transport
recognition

15

what is a channel protein?

molecules travel through them in facillitated diffusion

16

what is diffusion?

random movement of molecules from high to low concentration

17

What is active transport?

move against concentration gradient

18

what is endocytosis?

moving large molecules into cells

19

What is exocytosis?

Moving large molecules out of cells

20

Why are membranes fluid?

hydrophobic and hydrophilic interactions

phospholipids and proteins can move horizontally

no bonds

21

What is the importance of a membrane being fluid?

can repair itself

flexible

for endocytosis and exocytosis

22

How does a protein stay in the membrane?

Has no charge in the middle, and charge in the outside

Charged amino acids are either highly hydrophobic or hydrophilic, uncharged amino acids go in the middle

23

What travels through channel proteins?

ions, water solvable substances

24

What is the structure and properties of a membrane?

phosphate head - hydrophilic

Fatty acid tails - hydrophobic

selectively permeable

25

What is diffusion

high concentration to low concentration

down a concentration gradient

passive

26

How to calculate rate of diffusion

amount diffused / time taken

27

What factors effect rate of diffusion?

temperature, surface area, different in concentration and thin exchange surface

28

What is facilitated diffusion?

larger water soluable molecules

carrier proteins with binding sites

specific

passive

29

What is osmosis?

cytoplasm contains soluable molecules and ions which attract water

net movement of solvent molecules from an area lower loconcentration to higher concentration of solute

depends of water potential

30

osmosis

what happens if an animal cell in solution with a lower water potential?

net movement out of cell

31

osmosis

what happens to a plant cell in solution with lower water potential

contents shrink away from cell wall

32

Osmosis

what happens to an animal cell in solution with higher water potential

bursts

33

osmosis

what happens to a plant cell in solution with higher water potential

becomes firm and rigid

34

what is active transport?

against a concentration gradient

uses carrier proteins and requires ATP

35

What is an example of active transport?

epithelial cells lining the intestine, lots of mitochondria which produces ATP for active transport

36

How does active transport occur?

molecules bind to receptor site

atp binds to protein , hydrolysed into ADP and Pi

Protein changes shape

Molecule is released

Pi is released, protein reverts to original shape

37

what is water potential

the tendency of water to move from one area to another by osmosis

measured in kPa

38

what is the water potential of pure water

0

39

what is hypertonic

higher concentration of solutes when compared to another solution

40

what is hypotonic

lower concentration of solute when compared to another solution

41

what is isotonic

same solute concentration in two or more solutions