Unit 3 Membranes

Question 1

What is the Fluid Mosaic Model

Answer 1

different protein molecules stuck in a fluid phospholipid bilayer

Question 2

Define Selective permeability

Answer 2

the ability of some substances to cross the plasma membrane more easily than others

Question 3

define diffusion

Answer 3

tendency for particles of any substances to spread out into the available space

Question 4

Define passive transport

Answer 4

Diffusion across a membrane with no energy used
- from high concentration to low concentration
- goes down its concentration gradient

Question 5

what substances can pass through membrane using passive diffusion

Answer 5

• small non-polar molecules
• ions and molar molecules

Question 6

Define Osmosis

Answer 6

diffusion of water across a membrane

Question 7

define Tonicity

Answer 7

ability of a surrounding solution to cause a cell to gain or loss water

Question 8

what is a isotonic solution

Answer 8

equal concentration of solutes

Question 9

what is a hypotonic solution

Answer 9

low concentration of solutes in the environment

Question 10

what is a hypertonic solution

Answer 10

high concentration of solutes in the environment

Question 11

what happens when a solution is Hypotonic

Answer 11

water rushes into the cell to equalize the solution concentration
(Cell swells up)
-if animal cell swells too much it will lyse

Question 12

what is Lysis

Answer 12

breaking or bursting

Question 13

what happens when a solution is hypertonic

Answer 13

the water will move out of the cell
-animal cells will shrivel and die
-plant cells will also shrivel but rigid cell wall cannot change shape

Question 14

what is plasmolysis

Answer 14

plasma membrane pulls away from the cells wall

Question 15

what is osmoregulation

Answer 15

the control of water balance
-prevention of excessive uptake or loss of water

Question 16

What is facilitated diffusion

Answer 16

diffusion through the membrane with the help of transport proteins
(still a part of passive transport)

Question 17

define channel protein

Answer 17

simple channel for a molecule to pass

Question 18

define carrier protein

Answer 18

solute binds protein causing it to change

Question 19

define an aquaporin

Answer 19

allows the passage of water

Question 20

define Active transport

Answer 20

cell uses energy to move a solute against its concentration gradient

Question 21

Define exocytosis

Answer 21

large molecules are excreted from the cell

Question 22

Define endocytosis

Answer 22

large molecules and fluids are taken up by the cell

Question 23

define phagocytosis

Answer 23

“cellular eating”

Question 24

Define receptor mediated phagocytosis

Answer 24

receptor proteins are embedded in the membrane in an area that is lined by coat proteins