cell transport Flashcards

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1
Q

what is diffusion?

A

movement of particles from a region of high concentration to a region of low concentration along the concentration gradient

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2
Q

what is the concentration gradient?

A

difference in concentration between two regions

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3
Q

what molecules does diffusion allow to diffuse?

A

non-polar molecules
small molecules
lipid-soluable molecules

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4
Q

when does diffusion occur?

A

kinetic energy in molecules
concentration gradient
(no ATP needed)

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5
Q

what is facilitated diffusion?

A

passive transport via channel/carrier proteins

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6
Q

how do channel proteins carry out diffusion (properties)?

A

polar/charged molecules allowed through
can be gated
each protein is specific and will only allow one type of ion through

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7
Q

how do carrier proteins carry out diffusion (properties)?

A

particular molecule will attach to protein at binding site causing protein to change shape and release molecule through membrane

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8
Q

what molecules do carrier proteins allow to diffuse?

A

large molecules

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9
Q

what molecules do channel proteins allow to diffuse through?

A

polar/charged molecules

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10
Q

what does the graph look like for facilitated diffusion?

A

graph plateaus off
not directly proportional

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11
Q

what conditions do there have to be for facilitated diffusion to occur?

A

no concentration gradient
in a state of random movement due to kinetic energy
proteins present
(no ATP needed)

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12
Q

what is osmosis?

A

movement of water from an area of high water potential to an area of low water potential down a water potential gradient across a partially permeable membrane

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13
Q

what is water potential?

A

tendency for water molecules to enter or leave a solution by osmosis

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14
Q

what is the water potential of pure/distilled water?

A

0 kPa

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15
Q

how do you find the water potential of plant cells?

A

solute potential of cytoplasm + pressure potential

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16
Q

what happens to cells in HYPOTONIC solutions?

A

water potential of solution is higher
water moves into cell by osmosis

17
Q

what happens to an animal cell when water moves into it?

A

lysis (cell bursts)

18
Q

what happens to a plant cell when water moves into it?

A

turgidity (cell bursts)

19
Q

what happens to cells in HYPERTONIC solutions?

A

water potential of solution is lower
water moves out of the cell by osmosis

20
Q

what happens to an animal cell when water moves out of it?

A

crenation of the cell

21
Q

what happens to a plant cell when water moves out of it?

A

cell is plasmolysed

22
Q

what are isotonic solutions?

A

water potential value is the same in the solution and cell
(50% of cells are plasmolysed)

23
Q

what is active transport?

A

movement of ions and other molecules across the membrane via carrier proteins
from an area of low concentration to high concentration against the concentration gradient

24
Q

how does active transport via carrier proteins work?

A

molecules combine with specific protein
ATP transfers a phosphate group to carrier protein
protein changes shape and carries molecule across membrane into cell
molecule is released into cytoplasm
phosphate ion is released back to cytoplasm to recombine with ADP to make ATP
protein returns to original shape

25
Q

what are the properties needed for active transport to take place?

A

ATP
lots of mitochondria

26
Q

what are examples when active transport is used?

A

protein synthesis
muscle contraction
reabsorption of glucose in kidneys

27
Q

what happens in bulk transport?

A

bacterium will fit into receptor on phagocyte membrane
phagocyte will extend and engulf bacterium into a phagocyte vesicle (phagosomes)
lysosomes fuse with phagosome and empty enzymes onto it to form a phagolysosome
useful substances are absorbed from vesicle and undigested material is expelled by exocytosis

28
Q

what is endocytosis (bulk transport)?

A

movement of substances into cell
moves membrane to form vesicles that contain substances (needs ATP)