cell membrane + diffusion

Question 1

describe the components of cell membranes 4

Answer 1

-phospholipids
-glycoproteins
-glycolipids
-cholesterol

Question 2

what is the name of the structure of the cell surface membrane

Answer 2

fluid-mosaic model

Question 3

how thicc are cell surface membranes

Answer 3

10-20nm

Question 4

function of membranes 5

Answer 4

• selectively permeable
  -to separate organelles
  -provide an internal transport system
  -isolate enzymes that might damage cell
  -provides surface for reactions

Question 5

give an example of an internal transport system that happens due to membranes

Answer 5

endoplasmic reticulum

Question 6

give an example of enzymes that might damage a cell

Answer 6

lysosomes with hydrolytic enzymes

Question 6

what is the fluid above and below the phospholipid bilayer called

Answer 6

above: interstitial fluid
below: cytosolic fluid

Question 7

why is a membrane a FLUID mosaic model

Answer 7

layers aren’t fixed
layers can slide along
individual phospholipids can rotate
makes it fluid

Question 8

how to separate phospholipid bilayer

Answer 8

freeze it in liquid nitrogen
fracture layers (split) apart
you can observe using a transmission electron microscope

Question 9

what is the proof of fluid mosaic model-experiment

Answer 9

you can force 2 separate cells from different animals together
they will fuse into one and separate membrane protein will distribute over larger, new cell

Question 10

how to identify glycoprotein on a membrane

Answer 10

protein molecules with carbohydrate chains extending from them

Question 11

how to identify glycolipids

Answer 11

lipid portion with carbohydrate branched out

Question 12

what is the function of glycoproteins and glycolipids on the cell membrane

Answer 12

the immune system (e.g. lymphocytes) won’t detect the cell as foreign and therefore wont destroy it

Question 13

how to identify cholesterol on a membrane diagram

Answer 13

groups of hexagons embedded in the bilayer

Question 14

why is cholesterol found more in animal cells and why does this link to the function

Answer 14

cholesterol makes cell more rigid
animal cells don’t have cell walls so this supplies structure and strength

Question 15

how to identify an intrinsic protein on a membrane

Answer 15

protein that doesn’t cross entire membrane

Question 16

role of intrinsic protein

Answer 16

cell signalling using receptors

Question 17

how to identify extrinsic protein on a membrane

Answer 17

foes across entire protein

Question 18

another name for extrinsic protein

Answer 18

channel protein

Question 19

role of channel protein

Answer 19

allows substances to travel into the cell
polar molecules and ions move across the membrane by diffusion

Question 20

what does glyco mean in glycolipid and glycoprotein

Answer 20

contains sugar

Question 21

how to identify actin microfilaments

Answer 21

cylinder under phospholipid bilayer in cytoplasm

Question 22

role of actin microfilament

Answer 22

contract to change the shape of cell
allowing it to manoeuvre easily

Question 23

why can molecules travel through the phospholipid + examples

Answer 23

Non polar/ non charged molecules are free to diffuse
O2 / CO2

Question 24

4 factors that increase rate of diffusion

Answer 24

high temperature
short diffusion distance
large surface area
high concentration gradient

Question 25

rate of diffusion is proportional to equation ( Fick’s law)

Answer 25

(surface area x difference in concentration) / length of diffusion pass

Question 26

define facilitated diffusion

Answer 26

passive process
no ATP required
aids diffusion

Question 27

what is the role of transport proteins

Answer 27

transport large molecules/ions across cell membrane that cannot freely pass by aiding movement

Question 28

describe how transport proteins work

Answer 28

amino acids/sugar bind to protein
causing proteins to change shape
allowing substance through

Question 29

what is it called when a protein changes shape to allow protein to do its job

Answer 29

conformational change
changing tertiary structure of protein

Question 30

describe how a sodium-potassium pump works

Answer 30

sodium binds to binding sites in protein
phosphate from atp also binds to protein
protein phosphorolysed changing shape
sodium ions released
potassium ions bind to binding sites
protein dephosphorolysed -changing shape back to original+ releasing phosphate ion

Question 31

why are sodium ions released
and potassium ions bound

Answer 31

new shape repels sodium ions and attracts potassium ions

Question 32

what 2 things are used to aid this process

Answer 32

phosphate in ATP for conformational change + energy
electrochemical concentration gradient

Question 33

define cotransport protein

Answer 33

moving 2 substances with the same protein