chapter 4 key terms

Question 1

passive transport

Answer 1

movement across the cell membrane that does not require energy from the cell

Question 2

concentration gradient

Answer 2

the difference of concentration of a substance across a space, one area may have high concentration and other may be low

Question 3

equilibrium

Answer 3

when the concentration of a substance is equal throughout a space

Question 4

diffusion

Answer 4

the movement of a substance from an area of high concentration to an area of low concentration caused by the random motion of particles, equilibrium will result if substance is left to random movement

Question 5

osmosis

Answer 5

the diffusion of water through a permeable membrane from an area of high concentration to an area of lower concentration, water moves down the concentration gradient, type of passive transport

Question 6

hypertonic solution

Answer 6

a solution that causes a cell to shrink because of osmosis (water moves out of the cell)

Question 7

hypotonic solution

Answer 7

a solution that causes a cell to swell because of osmosis (water moves into the cell)

Question 8

isotonic solution

Answer 8

a solution that produces no change in cell volume because of osmosis (the water moves in and out of the cell at the same rate)

Question 9

ion channel

Answer 9

a doughnut-shaped transport protein with a polar pore through which certain ions can pass

Question 10

carrier proteins

Answer 10

a transport protein that binds to a specific substance on one side of the cell membrane and then carries it across the cell membrane and releases it on the other side

Question 11

facilitated diffusion

Answer 11

(passive) transport of substances through a cell membrane down a concentration gradient aided by carrier proteins

Question 12

active transport

Answer 12

transport of a substance across the cell membrane against its concentration gradient, this requires the cell to use energy (usually this energy comes from ATP)

Question 13

sodium-potassium pump

Answer 13

a carrier protein that transports 3 sodium ions out of the cell and 2 potassium ions into the cell, these ions are being actively transported against their concentration gradient

Question 14

endocytosis

Answer 14

the movement of larger substances into a cell by a vesicle (a pouch formed by the cell membrane)

Question 15

exocytosis

Answer 15

the movement of larger substances out of a cell by a vesicle

Question 16

receptor protein

Answer 16

a protein that binds to a specific signal molecule which enables the cell to respond to the signal molecule

Question 17

second messenger

Answer 17

created by a receptor protein when necessary, acts as a signal molecule in the cytoplasm, amplifies the signal of the first signal molecule, alters the chemical activity within the cell