Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
23 Cards in this Set
- Front
- Back
|
How many phospholipids in average cell membrane? how thick membrane? |
10^9 phospholipids in average cell 5nm thick |
|
|
Structure of phospholipid |
choline* I phosphate* * hydrophillic head group I glycerol* I 2x Fatty acid tails- hydrophobic |
|
|
Phospholipids normally found in inner leaflet |
phosphatidylethanolamine phosphatidyl serine- neg charged (used by proteins to interact with it) - normally found in inner leaflet of membrane -only found in outer leaflet if cell going through apoptosis -acts as a signal to immune system that cell is going through apoptosis and leads t recruitment of phagocytes -therefore can be used experimentally to differentiate alive cells from dying (apoptopic) cells -used to see if new dug is killing cells |
|
|
Phospholipids normally found in outer (extracellular) leaflet |
phosphatidylcholine sphingomyelin- not gylceride, backbone made from sphingosine -NH4 group instead of, found in higher conc in myelin leads to ridgidity of the surface -both uncharged |
|
|
What do all these phospholipids have in common? why? |
All these phospholipids- unsatuated which increased fluidity as they can't back closly together, increases freezing point |
|
|
Cholesterol structure size effect in membrane |
-ampipathic -polar head -ridged steroid ring structure (in flexible) -nonpolar hydrocarbon tail size- not as big as phospholipid designed to interact with phospholipid tail high density of cholesterol will immobolise first few carbons of lipid tail reducing flexibility -membrane more cholesterol dense will lead to thicker less fluid membrane -lipid rafts have high density cholesterol- prevent proteins from moving in membrane |
|
|
enzyme used to manufacturer cholesterol -inhibited by? -polymorphisum? (and treatment) |
HNG CoA reductase -inhibited by high levels of cholesterol- manufacturer rate dependent on intake -polymorphosium- manufactor too much cholesterol, can't be switched off. -poor HDL:LDL -take statins to inhibit HNG coA reductase to stop production of cholesterol |
|
|
3 things cholesterol does |
-makes steroid hormones -makes bile acids -transport of fats |
|
|
Cholesterol test |
tests for lipoproteins gives ratio of HDLs (good): to LDLs (bad) poor ratio associated with cardio vascular disease |
|
|
Steroid hormones |
-made from cholesterol -eg testosterone, oestrodiol, progesterones- sex hormones -cortisol- stress hormone -alderstone- mineralcorticoid move into cell, binds to target (nuclear receptor) and moves into nucleus causes change in gene expression can change what cell is designed to do |
|
|
Bile acids |
synthesised from cholesterol -help to digest fats -primary bile acids and secondary -inhibit own manufacture |
|
|
Fat soluble vitamins |
don't manufactor our own, have to get from diet Vitamin A- required for synthesis of retinol- photopigment Vitamin D- bone homoeostasis, calcium Vitamin K- blood clotting cascade |
|
|
How is cholesterol made? -starting product -rate limiting step -made in? |
starts from acetyl coA rate limiting step 3-hydroxy-3-methylglutaryl-coA --> mevalonic acid with HMG- CoA reductase enzyme made in the liver some ends up bound to lipoproteins and some converted to bile acids and stored in the gall bladder |
|
|
The gall bladder and bile acids |
some cholsterol ends up bound to lipoproteins and some converted to bile acids and stored in the gall bladder hepotocytes of liver arranged in hexagonal formation, each drain into bile duct -ca or protein rich diet develop gall stones -CCK causing constriction of gall bladder and release of bile but can suivive without it -bile- neutralises stomach acid so enzymes in s. intestines can work -protects s intestines from damage -emulsifies fats primary bile acids -toxic if left to build up -converted to secondary bile acids -negative inhibition of manufactor of bile salts |
|
|
Drugs and bile |
-drugs can be made to utilise bile acids recirculation mechanism -bile acids valuable and therefore recyled- transporter molecules help to do this - when want drugs to cross gut used these transporter molecules to stop them from being immediately excreted |
|
|
Emulsification |
role of bile acids converts fats to small droplets increasing SA allows fat to be digested |
|
|
transport of fats |
large chylomicron broken down into smaller molecule taken up by tissues -skeletal muscle- main tissue that uses fat as energy source -liver- takes up fat and converts it to acetyl coA -Adipose- stores fat -LDL- low density lipoprotein -phospholipids and lipases inbedded on surface -cholesterol and triglycerides found inside |
|
|
formation of phospholipid membrane -ball of phospholids- use -bilayer |
would form micelle-round ball of phospholipids -tails very compressed -continue to add phospholids form bilayer- freer to move and very fluid -allows hydrophobic molecules to enter membrane -cell manufactures lipids in SER -hydrophbic gas (O2) can move in freely formation of sphere - unfolded- energetically unfavourable -spontaeously forms ball -requires distrupt from proteins -ball of phospholipids- makes effective drug delivery system -pack ball with drugs, binds to cell membranes and releases drugs into cell -used for injected and inhaled drugs bilayer -tails interacte with each other -pressure of water molecules keeps bilayer together |
|
|
phospholipid movement |
-lateral diffuctsion - normally stoped by cholesterol -rotation- if tail further away and allows it -flexion- shows how compressed a phospholipid is -'flip-flop'- movement of phospholipid from one envelop to another- rare as hydrophillic head would need to move through hydrophobic section- enzymes flipase and flopase alow this (more in next section) |
|
|
Lipid density |
some parts of cell/ molecule need to stay in certain area of ceel/ membrane -saturation can effect yhis -saturated FA less free to move- as they are packed more closely together so denser, thicker membrane that is less flexiable -inner membranes (oraganelle membranes) tend to be more unsatuated as need to be flexible -membrane proteins will diffuse away after time |
|
|
Diffusion in cells demonstated by fusion cells |
-fuse mouse and human cells with electrical charge -tag species protein with specific marker -shows that proteins will freely diffuse around cell membrane |
|
|
consituation of mebrane -high cholesterol -low cholesterol glycolipds- what are they |
liver- high cholesterol, low glycolipids RBC- even higher cholesterol and lower glycolipids myeiln- high cholesterol and glycolipids mitochondria- low cholesterol, trace glycolipids bacterium-E.coli- 0 cholesterol 0 glycolipids glycolipids -sugar and lipid -used for recognition and signalling -give protection -myelin- wrapped around nerves so has high con glycolipids to protect nerve cells |
|
|
Lipid raft |
areas of higher concs of cholesterol and denser phospholipids -keeps proteins closer together -proteins still free to diffuse but anchored to lipids molecules and each other so harder |
