cell transport

Question 1

what is diffusion?

Answer 1

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

Question 2

what is the concentration gradient?

Answer 2

difference in concentration between two regions

Question 3

what molecules does diffusion allow to diffuse?

Answer 3

non-polar molecules
small molecules
lipid-soluable molecules

Question 4

when does diffusion occur?

Answer 4

kinetic energy in molecules
concentration gradient
(no ATP needed)

Question 5

what is facilitated diffusion?

Answer 5

passive transport via channel/carrier proteins

Question 6

how do channel proteins carry out diffusion (properties)?

Answer 6

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

Question 7

how do carrier proteins carry out diffusion (properties)?

Answer 7

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

Question 8

what molecules do carrier proteins allow to diffuse?

Answer 8

large molecules

Question 9

what molecules do channel proteins allow to diffuse through?

Answer 9

polar/charged molecules

Question 10

what does the graph look like for facilitated diffusion?

Answer 10

graph plateaus off
not directly proportional

Question 11

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

Answer 11

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

Question 12

what is osmosis?

Answer 12

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

Question 13

what is water potential?

Answer 13

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

Question 14

what is the water potential of pure/distilled water?

Answer 14

0 kPa

Question 15

how do you find the water potential of plant cells?

Answer 15

solute potential of cytoplasm + pressure potential

Question 16

what happens to cells in HYPOTONIC solutions?

Answer 16

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

Question 17

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

Answer 17

lysis (cell bursts)

Question 18

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

Answer 18

turgidity (cell bursts)

Question 19

what happens to cells in HYPERTONIC solutions?

Answer 19

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

Question 20

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

Answer 20

crenation of the cell

Question 21

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

Answer 21

cell is plasmolysed

Question 22

what are isotonic solutions?

Answer 22

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

Question 23

what is active transport?

Answer 23

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

Question 24

how does active transport via carrier proteins work?

Answer 24

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

Question 25

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

Answer 25

ATP
lots of mitochondria

Question 26

what are examples when active transport is used?

Answer 26

protein synthesis
muscle contraction
reabsorption of glucose in kidneys

Question 27

what happens in bulk transport?

Answer 27

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

Question 28

what is endocytosis (bulk transport)?

Answer 28

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