Cell Membranes

Question 1

what does non-polar mean?

Answer 1

lipid soluble

Question 2

what does polar mean?

Answer 2

water soluble

Question 3

what are living cells surrounded by?

Answer 3

plasma membrane

Question 4

what does the plasma membrane do?

Answer 4

separates contents of the cell

cell recognition/signalling

Question 5

what does plasma membrane hold?

Answer 5

components of some metabolic pathways

Question 6

what does plasma membrane regulate?

Answer 6

materials in and out of the cell

Question 7

how permeable is the membrane?

Answer 7

partially

Question 8

what is in the plasma membrane?

Answer 8

phospholipids
proteins
cholesterol
glycolipid
glycoprotein

Question 9

what is polar in phospholipid?

Answer 9

hydrophilic head

Question 10

what is non polar in phospholipid?

Answer 10

hydrophobic head

Question 11

what do phospholipids form?

Answer 11

bilayer

Question 12

how many layers of phospholipids are there?

Answer 12

2 layers

Question 13

how thick is the bilayer?

Answer 13

5nm

Question 14

what is the fluid mosaic model?

Answer 14

fluid - individual phospholipids/proteins can move freely through diffusion
mosaic - patter created by scattered protein molecules

Question 15

what does rising temp do to the membrane?

Answer 15

gives molecules more kinetic energy - makes membrane leaky increasing permeability

Question 16

what are extrinsic proteins?

Answer 16

proteins that embed in just outer or inner layer

Question 17

what are intrinsic proteins?

Answer 17

proteins that span the two layers

Question 18

what do hydrophobic and hydrophilic parts of protein molecule it next to?

Answer 18

hydrophobic and hydrophilic parts of phospholipid ensures proteins stay in the membrane

Question 19

what are glycolipids?

Answer 19

phospholipids with carbohydrate chains attached

Question 20

what are glycoproteins?

Answer 20

proteins with carbohydrate chains attached

Question 21

what else does the membrane contain?

Answer 21

cholesterol molecules

Question 22

what do phospholipids form?

Answer 22

bilayer

Question 23

what do phospholipids allow?

Answer 23

lipid soluble substances in and out of the cell

Question 24

what do phospholipids prevent?

Answer 24

water soluble substances getting in or out of the cell

Question 25

what does cholesterol reduce?

Answer 25

side-side movement of phospholipids in the bilayer

Question 26

what does cholesterol regulate?

Answer 26

fluidity

Question 27

what does cholesterol prevent?

Answer 27

prevents ion/ water leakage

Question 28

what does cholesterol maintain?

Answer 28

the mechanical stability of the cell

Question 29

what can proteins act as?

Answer 29

channels for polar substances

Question 30

what can proteins work as?

Answer 30

enzymes

Question 31

what do proteins form?

Answer 31

receptor sites for molecules

Question 32

function of proteins?

Answer 32

cell adhesion

Question 33

what must transport proteins use?

Answer 33

ATP due to it being active movement

Question 34

what do glycolipids form?

Answer 34

molecule binding sites

Question 35

what do glycolipids maintain?

Answer 35

membrane stability

Question 36

what do glycolipids have a role in?

Answer 36

cell attachment

Question 37

what is a glycoprotein?

Answer 37

receptor site for hormones/ neurotransmitters

Question 38

what do glycoproteins have a role in?

Answer 38

cell adhesion and cell signalling, intercellular lubrication

Question 39

what do glycoproteins act as?

Answer 39

antigens - cells can recognise

Question 40

how do cells communicate?

Answer 40

with signals such as hormones/ nuerotransmitters/ cytokenesis

Question 41

what must cells be able to detect?

Answer 41

signals involved in growth, development, movement, excretion

Question 42

how is communication most often done?

Answer 42

by hormones

Question 43

what is the target cell?

Answer 43

cell with receptor site for the hormone - complementary shape

Question 44

what happens when signal cell binds?

Answer 44

a response occurs

Question 45

what is passive transport?

Answer 45

no energy is required

Question 46

three methods of passive transport?

Answer 46

Diffusion Facilitated Diffusion Osmosis

Question 47

what is active transport?

Answer 47

energy is required

Question 48

two methods of active transport?

Answer 48

Active Transport | Bulk Transport

Question 49

what is diffusion?

Answer 49

net movement of molecules from a region of high concentration to a region of low concentration

Question 50

where do molecules move in diffusion?

Answer 50

down a concentration gradient, molecules have kinetic energy so move randomly - passive

Question 51

Factors that determine diffusion rate?

Answer 51

steepness of conc gradient - steeper more diffusion Temp - increase temp more kinetic energy Surface Area - increased surface area Type of molecule that is diffusing - large molecules diffuse slower, non polar molecules diffuse slower

Question 52

Three molecules that can diffuse through ?

Answer 52

oxygen - non polar CO2 - polar but small water - polar but very small

Question 53

what can diffuse through the bilayer?

Answer 53

large polar molecules e.g. glucose Na+ cant

Question 54

how do they get through the bi layer?

Answer 54

use a channel or carrier protein often complementary to one molecule - passive

Question 55

what is osmosis?

Answer 55

diffusion of water molecules down a water potential gradient from area of high water potential to area of low water potential across partially permeable membrane

Question 56

what is water potential?

Answer 56

tendency of water molecules to move from one place to another

Question 57

water potential of pure water?

Answer 57

0

Question 58

what is equilibrium?

Answer 58

when water potential on both sides is equal

Question 59

what do solutes make?

Answer 59

negative water potential

Question 60

animal cell placed in solution of high water potential?

Answer 60

water enters by osmosis down water potential gradient - cell bursts lysis

Question 61

animal cell placed in equal water potential?

Answer 61

no net movement of water by osmosis

Question 62

animal cell placed in lower water potential?

Answer 62

water leaves by osmosis down water potential gradient all shrivel- crenated

Question 63

plant cell in solution of high water potential?

Answer 63

water enters by osmosis down water potential gradient, cell becomes turgid doesn't burst due to cell wall

Question 64

plant cell in solution of equal water potential?

Answer 64

no net movement of water

Question 65

plant cell placed in solution of low water potential?

Answer 65

water leaves by osmosis down water potential gradient, protoplast shrivels plasmolysis occurs when membrane pulls away from wall

Question 66

what is active transport against?

Answer 66

concentration gradient, low-high concentration gradient

Question 67

what does active transport use?

Answer 67

energy supplied by ATP

Question 68

what is involved in active transport?

Answer 68

carrier proteins

Question 69

what are carrier proteins?

Answer 69

complementary in the molecule it transports

Question 70

what is active transport faster than?

Answer 70

diffusion

Question 71

what is active transport similar to?

Answer 71

facilitated diffusion It uses proteins in cell membrane

Question 72

why is active transport different to facilitated diffusion?

Answer 72

it is against a concentration gradient and requires energy

Question 73

how is energy supplied?

Answer 73

by ATP formed by aerobic respiration in the mitochondria

Question 74

what is bulk transport?

Answer 74

move large quantities of material in or out of the cell

Question 75

what does bulk transport require?

Answer 75

requires energy

Question 76

what is endocytosis?

Answer 76

bulk transport of material into a cell

Question 77

what is exocyctosis?

Answer 77

bulk transport of material out of a cell

Question 78

what is bulk uptake of solids?

Answer 78

endophagocytosis

Question 79

what is bulk uptake of liquids?

Answer 79

endopinocytosis

Question 80

what happens in stage 1 of exocytosis?

Answer 80

vesicle moves towards plasma membrane

Question 81

what happens in stage 2 of exocytosis?

Answer 81

vesicle joins plasma membrane

Question 82

what happens in stage 3 of exocytosis?

Answer 82

vesicle contents is released vesicle membrane becomes part of plasma membrane

Question 83

what happens in stage 1 of endocytosis?

Answer 83

cell spreads around object or area outside cell in solution

Question 84

what happens in stage 2 of endocytosis?

Answer 84

area enclosed becomes vesicle

Question 85

what happens in stage 3 of endocytosis?

Answer 85

contents of vesicle absorbed into cytoplasm vesicle membrane is recycled