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A Level Biology > Biological Membranes > Flashcards

Biological Membranes Flashcards

1
Q

membranes 3 main roles

A

cell signalling, site of chemical reactions & barrier to X’s environment

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2
Q

q

A

q

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3
Q

example of membranes as sites for chemical reactions: chloroplasts

A

thylakoids contain chlorophyll = photosynthesis

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4
Q

true or false facillitated diffusion uses ATP

A

false

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5
Q

True or False carrier proteins can do both facilitated diffusion & active transport

A

True and false - carrier proteins collectively can do both, but individual ones are specialized do one or the other;.

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6
Q

why is chemical signaling important

A

for cell to stay in contact with the environment & adjacent cells

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7
Q

Why can chemical signals trigger a response

in some cells and not others?

A

Only target cells carry the complementary receptor molecule for the
signal

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8
Q

what factor increases the number of different types of cell signaling receptors on a plasma membrane in the fluid mosaic model, other than proteins amino acids & shape?

A

carbohydrate chains attached to glycoprotein & glycolipid receptors increases variation

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9
Q

what is the total thickness of a cell membrane

A

5-10nm

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10
Q

who proposed the fluid mosaic model

A

Singer & Nicolson

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11
Q

what is the diameter of a water-filled protein channel

A

0.8nm

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12
Q

what are the 2 types of diffusion

A

facilitated & simple

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13
Q

crenated cell meaning

A

an ANIMAL cell that has lost water by osmosis

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14
Q

plasmolysis meaning

A

the process in which cells lose water in a hypertonic solution

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15
Q

hypertonic meaning

A

lowER solute concentration

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16
Q

turgid meaning

A

refers to cells or tissues that are swollen from water uptake

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17
Q

hypotonic meaning

A

low solute concentration

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18
Q

cytolysis meaning

A

IN ANIMAL CELLS ONLY: when cell swells due to water uptake, causing plasma membrane to burst releasing the cells contents into the extracellular environment

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19
Q

plasmolysed definition

A

a word to describe the shape of a plant CELL after water loss: cytoplasm of cell shrinks and membrane pulls away from cellulose cell wall

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20
Q

what are transport proteins

A

protein carriers & channels

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21
Q

name 2 passive transport processes

A

simple diffusion & facilitated diffusion

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22
Q

what is the difference between facilitated diffusion & simple diffusion

A

in facilitated molecules move across a partially permeable membrane (1) via protein channels/carriers

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23
Q

what are the similarities between glycolipids & glycoproteins in function and structure

A
  • both are antigens

- both have attached carbohydrate chains

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24
Q

what other functions do glycoproteins do that glycolipids don’t

A
  • receptors for chemical signalling

- cell adhesion

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25
Q

cholesterol function

A

stablailes phospholip bilayer & regulated fluidity

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26
Q

does an increase in cholesterol increase fluidity or decrease it

A

decreases permability & fluidity

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27
Q

what moleculues can pass through membrane freely in fluid mosaic model

A

water, oxygen & co2, steroid hormones

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28
Q

name 2 intrinsic proteins

A

carrier proteins & protein channels

29
Q

are lipids soluble in phospholipid bilayer?

A

true, soluble

30
Q

how is the concentration gradient maintained in a cell

A

molecules entering the cell are passed onto organelles to use in metabolic reactions = lowering their concentration in the cytoplasm

31
Q

where does active transport occur at the cell membrane

A

carrier proteins e.g aqua porins for water

32
Q

how do carrier proteins work

A

large molecules bind to carrier proteins (1) which changes shape to allow molecules to pass through

33
Q

true or false carrier proteins can carry out facilitated diffusion on any molecule

A

false- specific to the molecule

34
Q

name 5 things impacting the rate of simple diffusion

A
  • temperature
  • diffusion distance
  • surface area
  • size of diffusing molecule
  • concentration gradient
35
Q

Do smaller molecules diffuse faster than larger molecules

A

Yes, only applicable for partially permeable membrane

36
Q

how do (organic) solvents affect the rate of simple diffusion

A

increase in solvents = dissolves & disrupts cell membrane = increase in fluidity & permeabliliyty

37
Q

give an example of an organic solvent

A

benzene (non-polar alcholol)

38
Q

intrinsic proteins defintiion

A

embedded through both layers of a partially permeable membrane

39
Q

extrinsic proteins defintiion

A

present in 1 side of bilayer & could move between layers

40
Q

true or false extrincis proteins are fixtated in their position in the phospholipid bilyayer

A

false

41
Q

PAG what is the pigment that is released from beetroot

A

betalain

42
Q

what does ethanol do to cell membranes

A

dissolves lipids in cell membrane

43
Q

what impact does increase in temperature have on membrane

A

creates temproary pores

44
Q

active trnasportdefinition

A

movement of particles across a plasma membrane (1) against a concentration gradients (2) energy is recquiresd (3)

45
Q

what organelle is used in active transport across a cell surface membrane

A

carrier protein

46
Q

what organelle is used in facilitated diffusion across a cell surface membrane

A

channel protein

47
Q

what does ATP stand for

A

adensosine triphosphaye

48
Q

what does ADP stand for

A

adenosine diphosphate

49
Q

give exampels of active transport usages

A

glucose in small intestine into cappilaries

50
Q

what is bulk transport

A

used got transporting molecules that are too big for protein carriers

51
Q

what are vesicles

A

small membrane-bound sacs

52
Q

Name 2 times when ATP is needed during exocytosis

A

to form vesicles and to move them to the cell surface mambrane

53
Q

give the 3 step process to endocytosis

A

segment of cell surface membrane surrounds & encloses the particles (1) & brings it into the cell (2), enclosed in a vesicle(3)

54
Q

how are vesicles transported along the cytoskeleton

A

motor proteins along the cytoskeleton move vesciles

55
Q

endocytosis process (3)

A

a membrane-bound vesicle is transported towards the cell membrane (1) membrane and vesicle fuse together (2), fused site opens up, secreting the large particle (3)

56
Q

example of exocytosis process

A

vesicles in synapses got transmitting chemical signals

57
Q

In endocytosis what is the process called when a solid molecule is engulfed? give an example

A

phagocytosis, e.g white blood cell engulfing bacteria

58
Q

In endocytosis what is the process called when a liquid molecule is engulfed?

A

pinocytosis

59
Q

what are aquaporins

A

protein channels specifically for water, to allow fasterd iffusion into the cell

60
Q

what is flaccid

A

an adjective to describe plant TISSUE with plasmolyzed cells

61
Q

difference ebtween flaccid and plasmolyzed?

A

plasmolyzed talks about cell, flaccid talks about tissue

62
Q

do carrier proteins use facilitated diffusion or active transport

A

both

63
Q

water potential defintion

A

the pressure exerted by water molecules as they collide with a membrane or container

64
Q

what is water potential units

A

Pascals or Kilo pascals (KPa)

65
Q

what is the water potential of pure water?

A

0KPa

66
Q

True or false all solutions have a positive water potential?

A

false, all are under 0Kpa

67
Q

Complete the phrase: the higher the solute concentration in a solution the ___ the water potential

A

lower the water potential

68
Q

hydrostatic pressure definition

A

the pressure created by water in a closed system e.g in a cell; measured in KPa

69
Q

How do multicellular animal cells prevent crenation or cytolysis occuring?

A

make sure cells are continuously surrounded by solutions with equal water potential

A Level Biology (12 decks)

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