MCO - L 22-31 Flashcards
Function of membrane?
semi permeable ; detects & interprets changes to extracellular environment ; anchorage sites for extracellular proteins & cytoskeleton ; alternative environment (hydrophobic)
what makes the membrane fluid?
the lipids and proteins
list the proteins & their function in the membrane
– sensing & reacting ti environment; — cell to cell communication ; Flopase - flips phospholipids ; translocate - semipermeable barrier
why does the ER have an extracellular lumen
the proteins made inside the ER will be placed on the membrane therefore need extracellular environment.
what is PM mainly made of (using units)?
10^9 lipids in a typical cell, mainly made of phospholipids, glycolipids, cholesterol.
list where lipids are used and their place of function
fule for metabolism in the form to triacylglycerides; membranes as phospholipids, glycolipids and cholesterol ; signalling ag steroid hormones or Eicosanoids
in what solution are lipids soluble?
hydrophobic organic solvents eg. chloroform
list properties of micelle and liposomes
extensive, close in on themselves, self sealing
what makes up the tail of phospholipids and treacly glycerides?
FA
list the properties of FA
end in COOH, long hydrocarbon chains (14-24C), saturated or unsaturated
name the three numbering systems for carbon chains:
w1, w2… ; 1,2,3 ;
what does C18. ⃤9 mean
18 carbon chain with double bond between 9 and 10
what happens to melting point as double bonds increase?
decrease
what happens to hydrocarbon chains when unsaturated?
kink making irregular packing therefore decrease in melting point, increase in fluidity.
how do you obtain linoleic acid?
diet
what is lionleic acid used for in cells?
cell signalling
outline the synthesis of eicosanoids:
linoleic acid is synthesised into arachidonic acid which is then synthesised into eicosanoids
explain the process of pain signalling
inflammation signal -> membrane -> arachidonic acid released -> prostaglandin or eicosanoids -> inflammation or pain.
name the parts of a phospholipid
OH head , phosphate, glycerol , 2 FA
how can phosphates be modified?
by adding head groups by ester bonds eg. Choline
function of head groups
signalling
explain the mechanism for PLC
signal -> PCL -> cleave Inositol phosphate -> transmit signal into cell
what do sphingomyelin form and what is its function?
forms an amide not an ester, and use is signal transduction and apoptosis
glycolipid structure and function:
1 sugar derived from sphingosine ; immune response and cell-cell recognition and attachment.
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?
cholesterol
how is lateral diffusion measured?
flurophores are bleached blight and measure the rate of diffusion
what happens when temperature increases too much for a membrane?
increased fluidity, permeability and lipid molecular movement
what happens lipid composition as fluidity fluctuates?
unsaturated kinks, short chain, high temp.
chat does cholesterol do?
increase fluidity in the middle of the membrane, and decrease in the edges.
cholesterol structure
polar head, 4 rings, non polar hydrocarbon tail.
how is the lipid belayer asymmetric?
Dif lipid composition on either side. flippase catalyses flipping to maintain correct monolayer.
role of the er in the membrane:
synthesis & modification of lipids, proteins and carbohydrates.
types of membrane proteins:
integral, peripheral, proteins bound to integral, covalently anchored to membrane
how is topology maintained?
hydrophobic & electrostatic interactions
function and structure of ICAM?
several extracellular domains, cell-cell adhesion, immune system & endothelial cells, increased in inflammation ; 5 extracellular immunoglobulin domains, 1 transmembrane spanning helix, short cytoplasmic tail
function and structure of bacteriorhodopsin:
**
describe the structure of porins:
barrel shape + pore centre ; hydrophobic exterior and hydrophilic interior
what kind of interactions do parietal proteins form?
NOT COVALENT, only electrostatic, H- bond, van Der Waals
how are peripheral proteins anchored to the membrane?
hydrocarbon groups
role of ankyrin and spectrin:
maintain plasma membrane integrity based cytoskeletal structure.
function of carbohydrates:
attach to lipids & proteins to form a physical barrier against bacteria or viruses, mechanosensing and/or cell shape –> cell recognition and immune response
where are carbohydrates?
proteins in the form of oligosaccharide chains and in lipids in the form of sugar residue
why are transporters needed in membranes?
–
name the types of molecules that pass through the membrane:
small hydrophobic, small uncharged, water
name the characteristics of transport:
passive or active, specific, regulated
characteristic of carrier:
passive or active , for specific ions
what % of ATP is used for ATP hydrolysis in humans?
40%
active transporters:
ATP driven, light dependent, coupled
3 transpoters:
P type, F type, ABC transporter
how is stomach acid made?
CO2 diffuses, combine with water & carbonic acid, bicarbonate exchanged for CL-, H+ enters the lumen via CL- channel
explain the FISH technique:
grow cells on glass and fix, add in detergent to make permeable, incubate with chromosome specific fluorescent oligonucleotide probes.
are chromosomes evenly dispersed in the nucleus during interphase?
no
how is G2 different from G1?
different number of chromosomes - separated by 3 steps for interphase.
outline how unfertilised eggs showed protein expression
denatured -> s methionine -> Gell -> protein pattern
explain cyclin A expression in cell fertilisation
A accumulates, fertilised= rise and falls –> cyclin rises and falls in cell division
what was Tim hunts conclusion?
cyclin is the key controller of cell cycle
where r CDKs present?
all eukaryotic
how do you form an inactive hetrodynimic complex?
CDK + cyclin
how many cyclins and CDK are there?
2 cyclins and 3 CDK
how s phase cyclins expressed?
G1 cyclins-CDK complexes phosphorylate their targets which prep for S phase and promote the expression of cyclins
list how cyclins A, B, D, E control replication:
D&E - prep for S phase
A - replication of chromosomes
A&B - phosphorylate to activate spindle fibres
what signals are needed for cell proliferation or differentiation?
mitogenic signal, restriction point
explain the reentry of G1 from G0
mitogenic signals
