MCO - L 22-31

Question 1

Function of membrane?

Answer 1

semi permeable ; detects & interprets changes to extracellular environment ; anchorage sites for extracellular proteins & cytoskeleton ; alternative environment (hydrophobic)

Question 2

what makes the membrane fluid?

Answer 2

the lipids and proteins

Question 3

list the proteins & their function in the membrane

Answer 3

– sensing & reacting ti environment; — cell to cell communication ; Flopase - flips phospholipids ; translocate - semipermeable barrier

Question 4

why does the ER have an extracellular lumen

Answer 4

the proteins made inside the ER will be placed on the membrane therefore need extracellular environment.

Question 5

what is PM mainly made of (using units)?

Answer 5

10^9 lipids in a typical cell, mainly made of phospholipids, glycolipids, cholesterol.

Question 6

list where lipids are used and their place of function

Answer 6

fule for metabolism in the form to triacylglycerides; membranes as phospholipids, glycolipids and cholesterol ; signalling ag steroid hormones or Eicosanoids

Question 7

in what solution are lipids soluble?

Answer 7

hydrophobic organic solvents eg. chloroform

Question 8

list properties of micelle and liposomes

Answer 8

extensive, close in on themselves, self sealing

Question 9

what makes up the tail of phospholipids and treacly glycerides?

Answer 9

FA

Question 10

list the properties of FA

Answer 10

end in COOH, long hydrocarbon chains (14-24C), saturated or unsaturated

Question 11

name the three numbering systems for carbon chains:

Answer 11

w1, w2… ; 1,2,3 ;

Question 12

what does C18. ⃤9 mean

Answer 12

18 carbon chain with double bond between 9 and 10

Question 13

what happens to melting point as double bonds increase?

Answer 13

decrease

Question 14

what happens to hydrocarbon chains when unsaturated?

Answer 14

kink making irregular packing therefore decrease in melting point, increase in fluidity.

Question 15

how do you obtain linoleic acid?

Answer 15

diet

Question 16

what is lionleic acid used for in cells?

Answer 16

cell signalling

Question 17

outline the synthesis of eicosanoids:

Answer 17

linoleic acid is synthesised into arachidonic acid which is then synthesised into eicosanoids

Question 18

explain the process of pain signalling

Answer 18

inflammation signal -> membrane -> arachidonic acid released -> prostaglandin or eicosanoids -> inflammation or pain.

Question 19

name the parts of a phospholipid

Answer 19

OH head , phosphate, glycerol , 2 FA

Question 20

how can phosphates be modified?

Answer 20

by adding head groups by ester bonds eg. Choline

Question 21

function of head groups

Answer 21

signalling

Question 22

explain the mechanism for PLC

Answer 22

signal -> PCL -> cleave Inositol phosphate -> transmit signal into cell

Question 23

what do sphingomyelin form and what is its function?

Answer 23

forms an amide not an ester, and use is signal transduction and apoptosis

Question 24

glycolipid structure and function:

Answer 24

1 sugar derived from sphingosine ; immune response and cell-cell recognition and attachment.

Question 25

what is a sterol and has 4 carbon rings, effects membrane fluidity and is only found in animal and is the only steoroid in the plasma membrane?

Answer 25

cholesterol

Question 26

how is lateral diffusion measured?

Answer 26

flurophores are bleached blight and measure the rate of diffusion

Question 27

what happens when temperature increases too much for a membrane?

Answer 27

increased fluidity, permeability and lipid molecular movement

Question 28

what happens lipid composition as fluidity fluctuates?

Answer 28

unsaturated kinks, short chain, high temp.

Question 29

chat does cholesterol do?

Answer 29

increase fluidity in the middle of the membrane, and decrease in the edges.

Question 30

cholesterol structure

Answer 30

polar head, 4 rings, non polar hydrocarbon tail.

Question 31

how is the lipid belayer asymmetric?

Answer 31

Dif lipid composition on either side. flippase catalyses flipping to maintain correct monolayer.

Question 32

role of the er in the membrane:

Answer 32

synthesis & modification of lipids, proteins and carbohydrates.

Question 33

types of membrane proteins:

Answer 33

integral, peripheral, proteins bound to integral, covalently anchored to membrane

Question 34

how is topology maintained?

Answer 34

hydrophobic & electrostatic interactions

Question 35

function and structure of ICAM?

Answer 35

several extracellular domains, cell-cell adhesion, immune system & endothelial cells, increased in inflammation ; 5 extracellular immunoglobulin domains, 1 transmembrane spanning helix, short cytoplasmic tail

Question 36

function and structure of bacteriorhodopsin:

Answer 36

**

Question 37

describe the structure of porins:

Answer 37

barrel shape + pore centre ; hydrophobic exterior and hydrophilic interior

Question 38

what kind of interactions do parietal proteins form?

Answer 38

NOT COVALENT, only electrostatic, H- bond, van Der Waals

Question 39

how are peripheral proteins anchored to the membrane?

Answer 39

hydrocarbon groups

Question 40

role of ankyrin and spectrin:

Answer 40

maintain plasma membrane integrity based cytoskeletal structure.

Question 41

function of carbohydrates:

Answer 41

attach to lipids & proteins to form a physical barrier against bacteria or viruses, mechanosensing and/or cell shape --> cell recognition and immune response

Question 42

where are carbohydrates?

Answer 42

proteins in the form of oligosaccharide chains and in lipids in the form of sugar residue

Question 43

why are transporters needed in membranes?

Answer 43

--

Question 44

name the types of molecules that pass through the membrane:

Answer 44

small hydrophobic, small uncharged, water

Question 45

name the characteristics of transport:

Answer 45

passive or active, specific, regulated

Question 46

characteristic of carrier:

Answer 46

passive or active , for specific ions

Question 47

what % of ATP is used for ATP hydrolysis in humans?

Answer 47

40%

Question 48

active transporters:

Answer 48

ATP driven, light dependent, coupled

Question 49

3 transpoters:

Answer 49

P type, F type, ABC transporter

Question 50

how is stomach acid made?

Answer 50

CO2 diffuses, combine with water & carbonic acid, bicarbonate exchanged for CL-, H+ enters the lumen via CL- channel

Question 51

explain the FISH technique:

Answer 51

grow cells on glass and fix, add in detergent to make permeable, incubate with chromosome specific fluorescent oligonucleotide probes.

Question 52

are chromosomes evenly dispersed in the nucleus during interphase?

Answer 52

no

Question 53

how is G2 different from G1?

Answer 53

different number of chromosomes - separated by 3 steps for interphase.

Question 54

outline how unfertilised eggs showed protein expression

Answer 54

denatured -> s methionine -> Gell -> protein pattern

Question 55

explain cyclin A expression in cell fertilisation

Answer 55

A accumulates, fertilised= rise and falls --> cyclin rises and falls in cell division

Question 56

what was Tim hunts conclusion?

Answer 56

cyclin is the key controller of cell cycle

Question 57

where r CDKs present?

Answer 57

all eukaryotic

Question 58

how do you form an inactive hetrodynimic complex?

Answer 58

CDK + cyclin

Question 59

how many cyclins and CDK are there?

Answer 59

2 cyclins and 3 CDK

Question 60

how s phase cyclins expressed?

Answer 60

G1 cyclins-CDK complexes phosphorylate their targets which prep for S phase and promote the expression of cyclins

Question 61

list how cyclins A, B, D, E control replication:

Answer 61

D&E - prep for S phase A - replication of chromosomes A&B - phosphorylate to activate spindle fibres

Question 62

what signals are needed for cell proliferation or differentiation?

Answer 62

mitogenic signal, restriction point

Question 63

explain the reentry of G1 from G0

Answer 63

mitogenic signals