Cell Membrane and Transport

Question 1

function of cell membrane

Answer 1

to maintain cell integrity and be a selective barrier and controls what goes in and out

Question 2

describe micelle

Answer 2

single sheet

stable ball structures - hydrophilic heads face outwards

Question 3

describe bilayer

Answer 3

two layered membrane

Question 4

size of bilayer membrane

Answer 4

7nm

Question 5

why is cancer cells difficult to treat

Answer 5

self mutated self cells

hard to detect

Question 6

how does cell membrane keep its shape

Answer 6

cytoskeleton

Question 7

can lipids pass

Answer 7

lipid soluble such as hormones can

Question 8

describe phospholipid behaviour when:

• longer tails
• higher temperature
• more unsaturated tails

Answer 8

the less fluid the membrane = more hydrophobic region
the more fluid the membrane = animals respond by increaseing proportion of unsat.tails
the more fluid the membrane

Question 9

what is a glycoprotein

Answer 9

protein with carbohydrate attached

Question 10

what is a glycolipid

Answer 10

lipid with carbohydrate attached

Question 11

describe intrinsic proteins

Answer 11

found in inner/outer layer spanning whole membrane (transmembrane protein)
- fixed or flaot about

Question 12

example of intrinsic proteins

Answer 12

receptors/channels/enzymes/aquaporins

Question 13

describe extrinsic proteins

Answer 13

found on outer/inner surface

Question 14

what are glycoproteins/glycolipids

Answer 14

proteins and lipids with short, branching carbohydrates chains attached

Question 15

describe cholesterol

Answer 15

small molecules that fit in between phospholipid molecules

Question 16

purpose of cholesterol

Answer 16

strengthens bilayer

increases fluidity at low tempratures

Question 17

cholesterol in animals

Answer 17

1:1

Question 18

cholesterol in plants

Answer 18

less

Question 19

purpose of glycolipids/glycoproteins for cell membrane

Answer 19

hydrogen bond with water molecules to stabilise membrane structure

Question 20

what is a glycocalyx

Answer 20

made from glycoproteins and glycolipids to form sugar coating to cell

Question 21

what do glycocalyx do in bacteria

Answer 21

protects from virus

Question 22

what is glycocalyx mainly formed from in animals

Answer 22

glycoproteins

Question 23

what do glycoproteins/glycolipid do

Answer 23

cell to cell recognition
signalling receptors
endocytosis
cell adhesion

Question 24

what is glycosylation

Answer 24

using enzymes to modify a molecule by adding sugar molecule

Question 25

cell signalling steps

Answer 25

Target cell; 
Specificity; 
Cell signalling molecule; 
Complementary; 
Trigger secondary messenger; 
extracellular/intracellular signal; 
Binding to receptor;

Question 26

what are G proteins

Answer 26

act as a switch to bring second messenger

Question 27

ways receptor can change activity of the cell

Answer 27

opening of ion channel

acting as intracellular receptor

Question 28

what is phosphorylation

Answer 28

active/deactive enzymes
adding phosphate group
making molecule trapped in cell due to charge

Question 29

what enzymes activate phosphorylation

Answer 29

kinase

Question 30

what enzymes deactivate phosphorylation

Answer 30

phosphatases

Question 31

definition of diffusion

Answer 31

Passive process of net movement of ions from area of high conc. To low conc. Down concentration gradients, using kinetic energy

Question 32

definition of faciliated diffusion

Answer 32

passive process
movement of larger molecules and ions
with channel/carrier proteins

Question 33

whats the difference between channel/carrier proteins

Answer 33

carrier proteins can flip between two shapes and need a trigger

Question 34

definition of osmosis

Answer 34

Passive movement of water from area of high concentration to low concentration through partially permeable membrane.

Question 35

describe osmosis in animals

• pure water
• concentrated

Answer 35

bursts because cell membrane cannot withstand pressure

shrinks

Question 36

describe osmosis in plants

• pure water
• concentrated

Answer 36

turgid

plasmolysis

Question 37

describe plasmolysis

Answer 37

water leaves cell by osmosis
protoplast pulls from cell wall
pressure potential = 0
about to be plasmolysed = incipient plasmolysis

Question 38

definition of water potential

Answer 38

tendency for water to move out of solution

Question 39

what is pure water water potential

Answer 39

0

Question 40

definition of hypotonic

Answer 40

water enters the cell

animal cell is lysed + plant cell is turgid

Question 41

definition of isotonic

Answer 41

same water potential

animal cell is normal + plant cell is turgid

Question 42

definition of hypertonic

Answer 42

water leaves the cell

animal cell is shriveled + plant cell plasmolysed

Question 43

definition of bulk transport

Answer 43

large quantities of material transported

Question 44

definition of endocytosis

Answer 44

engulfing material into cell by cell surface to form small sac

Question 45

three ways of endocytosis

Answer 45

phagocytosis
pinocytosis
recepter mediated endocytosis

Question 46

difference between phagocytosis and pinocytosis

Answer 46

uptake of solid material/liquid material

Question 47

definition of exocytosis

Answer 47

removal of materials from cell by fusing with the membrane

Question 48

definition of active transport

Answer 48

Movement of ions from low concentration to high concentration, through a carrier protein, using energy from ATP.

Question 49

describe sodium potassium pump

Answer 49

ATP + 3Na bind to protein
ATP hydrolysis and release energy
protein changes shape and sodium ions out of the cell
2K+ + ADP + P released into cell

Question 50

use of sodium ions in organisms

Answer 50

impulses
maintain water potential
absorb glucose

Question 51

definition of mosaic fluid phospholipid bilayer

Answer 51

moving constantly mosaic meaning proteins scattered about