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52 Cards in this Set
- Front
- Back
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glycerolipids are made up of? |
gycerol + fatty acid at the 2 carbon |
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sphingolipids are made up of? |
sphingosine + fatty acid |
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What is a glycerophospholipid? |
glycerol + phospho because it has the phosphatdiyl (-) +R group |
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what are the types of glycerophospholipids and how do their chargers work? |
it's the R group at the top that tell you which kind it will be Inositol (PI) Serine (PS) ====== net negative charge Choline (PC) Ethanolamine (PE) ==== neutral |
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why inositol (PI) R group makes the glycerophospholipid net negative charge? |
because it already has the P- phosphatidiyl group and then you add the R group that is neutral which makes it keep that negative charge |
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what is the most common gylcerophospholipid in membrane composition? |
phosphatidylacholine (35-75%) |
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how much of the membrane composition is negatively charged? |
substantial portion (~20%) |
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what is the proportion of cholesterol to phospholipid in membrane composition? |
as much cholesterol as phospholipid |
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what is the proportion of saturated/unsaturated fatty acids in plasma membrane vs organelles? |
more saturead fatty acids in plasma membrane more unsaturated in organelles so that it gives a nice curve of the membrane |
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where are fatty acids found on glycerophospholipids? |
carbon 1 and 2 |
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how can glycerophospholipids vary in terms of length and saturation? |
length: 12-122 carbons, usually 16-18 degree of saturation: no double bonds (saturated with H), to 3 double bonds (unsaturated) |
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what are the types of fatty acids? |
1. stearic acid 2. oleic acid 3. linoleic acid 4. linolenic acid |
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Stearic acid has ... carbons ... double bonds and is found in ....? |
18 carbons 0 double bonds enriched in meats |
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Oleic acid has ... carbons ... double bonds and is found in ...? |
18 carbons 1 @ position 9 enriched in olive oil |
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Linoleic acid has ... carbons ... double bonds .. and is found in ... ? |
18 carbons 2 @ position 6 & 9 omega 6 fatty acid |
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Linolenic acid has ... carbons ... dobule bonds ... and is found in ...? |
18 carbons 3 @ position 3 ,6,9 omega 3 fatty acids |
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what are the factors that influence the fluidity of the membrane? |
1) level of unsaturated:saturated fatty acids 2) temperature 3) cholesterol 4) proteins 6) lipid rafts! |
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how does the level of saturation affect fluidity of membrane? |
the more unsaturated the more fluid. |
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how does temperature affect the fluidity of the membrane? |
low temperature means more rigidity |
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how does cholesterol affect fluidity of membrane? |
at high temperatures it prevents it from being too fluid, increases melting point at low temperature it prevents it from being too stiff tooo much cholesterol makes it too rigid makes lipid rafts. too little is too fluid. |
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What does membrane asymmetry look like? |
glycolipids on outer membrane: because it was made it was glycosylated in the Golgi so it was put on the surface more PC (choline) in outer membrane of PM PS (serine) in the inner membrane of PM toward cytosol
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what are the different types of lipid transport within a cell? |
1. lateral diffusion 2. transbilayer movement 3. vesicular transport 4. monomeric exchange (btween organelles) |
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which type of lipid transport is fastest, which one is slowest? |
the fastest one is lateral diffusion then vesicular transport the slowest one is transbilayer movement unless catalyzed |
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which type of lipid transport within the cell is most rare? |
monomeric exchange |
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What is used in catalyzed transbilayer lipid movement? |
flippase floppase scramblase |
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what do flippases do? |
in transbilayer movement: takes phospholipids from the ECM and takes it intracellular ATP/ADP dependent (phosphotydil serine is on the inside) |
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what do floppases do? |
takes it form inside and puts it ouside ATP dependent |
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what is the substrate for flippase? |
Phosphotdil serine (-) |
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What do scramblases do? |
swamps one from the ouside with one from the inside Ca+ dependent |
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What can changes in the asymmetry of the membrane lead to? |
can lead to disease PS (serine) belongs in the inner membrane when it is out it tell the body that the cell is sick |
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what are some diseases where asymmetry of membrane is changed? |
diseases causing or caused by membrane asymmetry: sickle-cell anemia thalassemia malaria |
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What are membrane rafts? |
part of the membrane bilayer: SIGNALLING PLATFROMS -small (10-200nm) -heterogenous -more ordered and tightly packed than surrounding bilayer, also more cholsterol than other parts |
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what are membrane rafts composed of? Brief. |
cholesterol sphingolipids glycerophospholipids specialized proteins (caveolin, flotillin) |
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what is the function of membrane rafts? |
concentrate/separate proteins within the plane of the bilayer: to get or not get signal transduction compartmentalize cellular processes |
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what are membrane rafts composed of? |
Resident proteins: caveolin, flotilin, GPI-anchored proteins (e.g. prion protein) Tourist signalling proteins: not always there. some G-proteins non-receptor tyrosine kinases Cytoskeleton/Adhesion proteins :actin, vinculin, cadherin etc |
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What is special about membrane rafts/thickness of membrane? |
lipid rafts have increased conc cholesterol (2x more), rigid af enriched in proteins containing: -longer transmembrane domains -glycosylphosphatidylinositol (GPI) anchors +caveolin + flotilin + lots of lectins |
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what types of membrane rafts are there? |
2 types |
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what are the types of membrane rafts? |
1) caveolae 2) planar lipid rafts |
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what are caveolae membrane rafts? |
small, flask-shaped invaginations of the plasma membrane enriched in caveolin, evetually pinch off in vesicles but dont use clathrin |
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what are planar lipid rafts? |
found in neurons and enriched in flotillin |
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How are membrane rafts signalling rafts? |
caveolin and flotillin recruit signallin proteins signalling can be promoted or dampened |
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how can signalling be promoted by membrane rafts? |
receptors and effectors organized in rafts (same raft) to promote signalling |
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how can signalling be dampened by membrane rafts? |
receptor and effectors separated by raft organization to prevent signalling |
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What are the functions of membrane rafts? |
1. organizing centres: assembly of signalling molecules, signalling can be promoted or dampened 2. Effects membrane fluidity: less lateral diffusion 3. involved in trafficking of membrane proteins |
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What diseases are membrane rafts involved in? |
1. Alzheimer disease -platforms for production of amyloid-B (neurotoxic protein) 2. Prion Disease 'mad cow' -normal prion protein (PrPc) is converted to abnormal proteins (PrPsc) in lipid rafts (GPI anchor required) |
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what are the main challenges in the field of study of membrane rafts (what an exciting time to be alive)?! |
difficult to study lipid rafts in intact cells too small to be resolved by light microscopy manipulation of cholesterol: sequestration, depletion or removal ** dont use too much cholesterol chelator, difficult |
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what is the cytoskeleton? |
network of protein fibers that extend throughout the cytoplasm nomenclature is based on size |
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What are the functions of cytoskeleton? |
1. cell adhesion and movement (migration) 2. cell shape and structure: microtubules 3. endocytosis/exocytosis (secretion and recycling): highways to vesicles 4. organelle/protein transport 5. mitosis/cytokinesis 6. cilia and flagella 7. muscle contraction - etc |
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what are the three types of cytoskeleton? |
Microtubules Actin microfilaments Intermediate filaments |
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What is the structure, diameter and example of microtubules? |
protofilaments 25nm tubulin (alpha and beta subunits) |
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what is the structure, diameter and example of microfilaments(actin)? |
double helix 6-7 nm actin |
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what is the structure, diameter and example of intermediate filaments? |
two anti-parallel helices form tetramers 10nm Vimentin (mesenchymal cells) Desmin (muscle cells) Keratins (epithelial cells) Nuclear Lamins |
