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biology > cc3 > Flashcards

cc3 Flashcards

1
Q

what does the fluid mosaic model contain?

A

phospholipid bilayer, fatty acid, phospholipid, carrier protein, hydrophilic channel, extrinsic protein, intrinsic protein, glycoprotein, carbohydrate, glycocalyx

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2
Q

why do cells need membranes?

A

control entry and exit of substances, contain cell contents + compartmentalise cell processes, communication with external environment, site of chemical reactions, allow cells to change shape, transport and packaging within a cell

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3
Q

what are cell membranes made of?

A

composed of phospholipids

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4
Q

how do water soluble substances pass through the cell?

A

through passageways made of proteins

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5
Q

why do fats and water not mix?

A

water is polar and fats are non polar so don’t form hydrogen bonds with water

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6
Q

what happens when fats and water are put together?

A

fats are hydrophobic and lie on the surface to reduce area in contact with water

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7
Q

what is the structure of phospholipids?

A

glycerol backbone, two fatty acid tails and a phosphate group

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8
Q

why is it called the fluid mosaic model?

A

it isn’t a fixed structure, individual phospholipids can move, can rotate on their axis, they can ‘swap’ places with the phospholipids next to them and rarely with the one opposite

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9
Q

what are the type of proteins?

A

carrier protein (passive), gated-channel protein, channel protein, carrier protein (active)

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10
Q

what is the definition of osmosis?

A

the net passive diffusion of water molecules across a selectively permeable membrane from an area of high water potential to an area of lower water potential

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11
Q

what is meant by net movement?

A

movement in 1 direction - movement in other direction.
water moves in both directions at the same time

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12
Q

what is meant by selectively permeable?

A

only permeable to certain molecules and not to all

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13
Q

what is water potential?

A

the measure of free energy of water molecules and its tendency to move from one solution to another (higher to lower)

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14
Q

what is the highest water potential?

A

0KPa = pure water. all solutions have a lower water potential than water (negative values)

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15
Q

why does water move?

A

water molecules are weakly bound to the solute molecules so fewer are free to move

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16
Q

what is the equation for water potential?

A

solute potential + pressure potential

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17
Q

what type of value is solute potential?

A

negative

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18
Q

what type of value is pressure potential?

A

positive

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19
Q

how permeable are cell walls?

A

fully permeable to all molecules

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20
Q

why and how does a plant cell develop high internal pressures?

A

the cell wall is inelastic and strong and pushes against the cytoplasm of the cell pushing against the cell wall causing the cell to develop high internal pressures in the right conditions

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21
Q

what is a hypotonic solution?

A

the water potential is higher outside the cell than the inside (due to there being lower solute potential present = more free water = higher water potential)

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22
Q

what is isotonic solution?

A

inside and outside of cells each have the same amount of free water so there’s no net movement of water

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23
Q

what is a hypertonic solution?

A

has less free water because there is more solute present so there is a lower water potential compared to inside cell

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24
Q

what is turgor pressure?

A

when the cajole is full it presses against the cell wall creating a normal internal cellular pressure

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25
Q

what does turgor pressure do in young and soft parts of the plant?

A

provides strength

26
Q

what happens when there’s reduced turgor pressure?

A

the plant wilts

27
Q

when is there no net movement of water?

A

the water potential of plant tissue and its surroundings are equal

28
Q

what is incipient plasmolysis?

A

when the cell is neither turgid nor plasmolysed. the cell membrane is withdrawn from the cell wall in places and the cell contents exert no pressure on the cell wall

29
Q

what is active processes?

A

need energy in the form of ATP, used if diffusion cannot meet needs of cell (not quick enough), to move molecules from an area of low concentration to high concentration

30
Q

what is passive processes?

A

does not require energy in form of ATP, to transport molecules across cell membrane from a high concentration to a low concentration

31
Q

what is active transport?

A

requires energy, against concentration gradient, energy supplied by ATP, molecules attach to specific proteins in membrane which change shape due to energy from ATP

32
Q

how does a carrier proteins shape change?

A

due to energy from ATP

33
Q

what is shape of the carrier protein complementary to?

A

the molecules they carry

34
Q

what does a 1 way flow-molecule mean?

A

it only fits into the carrier protein on 1 side

35
Q

when and why does active transport stop?

A

in the presence of a respiratory inhibitor. respiration produces ATP. no ATP = no active transport

36
Q

what is an example of a respiratory inhibitor?

A

cyanide

37
Q

what is bulk transport?

A

moving large quantities in and out of the cell

38
Q

what is exocytosis? explain what happens

A

process where materials are secreted out of the cell. vesicles pinch off from the sacs of the golgi body and move towards the cell membrane. vesicles fuse with the membrane and release their contents outside the cell

39
Q

what molecules are secreted by exocytosis?

A

digestive enzymes, hormones, mucus and milk

40
Q

what is endocytosis?

A

when a cell takes in substances by surrounding them with a section of the cell membrane to form a vesicle

41
Q

what are the two types of endocytosis?

A

phagocytosis and pinocytosis

42
Q

what is phagocytosis?

A

solid particles or whole cells are brought into the cell, contents are digested by lysosomes then diffuse out of vesicles into cytoplasm

43
Q

what is pinocytosis?

A

similar to phagocytosis but with liquid

44
Q

what is co-transport?

A

a type of facilitated diffusion that brings molecules and ions into cells simultaneously

45
Q

why is co-transport a type of facilitated diffusion?

A

movement from high to low concentrations through a carrier protein

46
Q

how is glucose transported into a cell by co-transport?

A

glucose and sodium ions bind to carrier protein at the same time and the protein changes shape to deposit them inside the cell. sodium = high to low conc. glucose = low to high

47
Q

how do glucose and sodium move to the other side of the cell?

A

diffusion

48
Q

how does glucose leave the cell?

A

through a carrier protein (facilitated diffusion) from high to low conc

49
Q

how does sodium ions leave the cell?

A

active transport by a carrier protein which brings in potassium (sodium-potassium pump)

50
Q

what does the sodium-potassium pump do?

A

maintain concentration gradient as the sodium enters the cell is removed leading to a lower concentration being outside the cell. this means co-transport can keep happening as sodium is necessary for glucose to enter the cell

51
Q

what is diffusion?

A

a passive method of transport across a cell membrane from an area of high concentration to lower concentration

52
Q

what is simple diffusion?

A

across phospholipid bilayer

53
Q

what molecules can be transported by simple diffusion?

A

small, non-polar or lipid soluble molecules, oxygen, carbon dioxide, fat soluble vitamins (A,D,E,K)

54
Q

what is rate of diffusion dependent on?

A

surface area of membrane, length of diffusion pathway, steepness of concentration gradient, temperature, membrane permeability

55
Q

how does surface area of membrane affect rate of diffusion?

A

increase in SA, increases rate, folds in membrane increase SA

56
Q

how does length of diffusion pathway affect rate of diffusion?

A

shorter= increase rate. falttened cells, thinner membrane, less layers of cells = shorten diffusion pathways

57
Q

how does steepness of concentration gradient affect rate of diffusion?

A

larger difference = faster diffusion, circulation and ventilation = increase concentration gradient

58
Q

how does temperature affect rate of diffusion?

A

increase temp = more kinetic energy = faster movement = increase rate

59
Q

how is membrane permeability affected?

A

by salt concentrations, presence of detergents and organic solvents

60
Q

what is facilitated diffusion?

A

across a specific protein carrier or channels, passive, charged particles or molecules, large molecules that are too big for simple diffusion, high to low concentrations

61
Q

what is facilitated diffusion dependent on?

A

temperature, number of carrier proteins

62
Q

when is maximum rate reached for facilitated diffusion?

A

when there is a high concentration of substances being transported = all protein carriers are in use

biology (10 decks)

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