2.1.5 biological membranes

Question 1

cell surface membranes

Answer 1

work with cytoskeleton to provide some structural support for cell
- act as partially permable barrier between cell and its enviroment
-involved in intercellular cell signalling

Question 2

membranes surrounding organelles

Answer 2

compartmentalisation
controls what enters and leaves an organelle
involved in intracelluler cell signalling

Question 3

membranes within organelles

Answer 3

partially permeable barrier between parts of an organelle
can be sites of chemical reactions

Question 4

structure of plasma membrane

Answer 4

Fluid mosaic model
fluid- flexible and can change structure or shape
mosaic- studded with phospholipids

Question 5

cell signalling

Answer 5

communication between cells

Question 6

4 ways to transport across a membrane

Answer 6

diffusion
active transport
osmosis
facilitated diffusion

Question 7

selective permeability

Answer 7

certain molecules can move across easily when others cant or need help

Question 8

method across membrane depends on

Answer 8

size
if charged or polar
if needs to move down or against a concentration gradient

Question 9

diffusion

Answer 9

net movement of particles from region of higher concentration to region of lower concentration down a concentration gradient until equilibrium is reached

Question 10

what particles can cross by simple diffusion

Answer 10

CO2
O2
small
non charged
non polar

Question 11

facilitated diffusion

Answer 11

diffusion across a membrane through a protein channel
polar molecules and ions pass through channel proteins

Question 12

carrier proteins

Answer 12

change shape when specific molecule binds

Question 13

How active transport works

Answer 13

molecule binds to receptor in channel of carrier protein
ADP binds and protein changes shape opening to inside of cell
ion is released
phosphate released and reforms ATP
returns to original protein

Question 14

Bul transport

Answer 14

energy in ATP causes change in shape of cytoskeleton
moves larged charged or polar molecules

Question 15

Endocytosis

Answer 15

transport into a cell

Question 16

how are solids transported into a cell

Answer 16

phagocytosis

Question 17

how are liquids transported into cell

Answer 17

pinocytosis

Question 18

exocytosis

Answer 18

release of something from a cell

Question 19

Osmosis

Answer 19

movement of water across a partially permeable membrane from high to low water potential

Question 20

water potential symbol

Answer 20

psi
Ψ

Question 21

water potential definition

Answer 21

pressure exerted on a membrane or container

Question 22

what concentration of solute does a high water potential have

Answer 22

low concentration of solution and hidh concentration of water

Question 23

what units is water potential

Answer 23

pascals
Pa

Question 24

what water potential is pure water

Answer 24

zero

Question 25

what happens to water potential if you add solutes

Answer 25

becomes more negative

Question 26

hypertonic

Answer 26

lower water potential than in cell
water leaves cell causing it to shrink

Question 27

hypotonic

Answer 27

higher water potential than in cell
water enters cell so it swells and bursts

Question 28

isotonic

Answer 28

same water potential in and out of cell

Question 29

how do plants maintain turgor pressure

Answer 29

water enters and pushes against membrane by increasing hydrostatic pressure
cytoplasm stays attached to plasma membrane