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24 Cards in this Set
- Front
- Back
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General Features of Membranes
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non-covalent assemblies
2D fluids asymmetrical |
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General Functions of a membrane
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B- is for boundary, maintain
F- is for filter, highly selective G - Generates electrical gradient A- adhesion S - Sensor of stimuli |
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What are Glycerol-based lipids?
GEPA |
2 tails, major type, phosphate in there
alcoholic base glycerol backbone vary in size, shape, polarity Fatty acids important for function GEPA |
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How do you form glycerophospholipids?
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use a phospholipid intermediate that lacks a base then bind to glycerol
fatty acid links to CoA, then to glycerol 3-phosphate. then loses CoA and uses acyl tranferase toin cytosol, then join CDP choline, CMP |
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What is Diacylglycerol? DAG?
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lacks phopshate and a base, can form a glycerophospholipd
made dring PL synthesis by C hydrolysis of polar head groups |
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What is the deal with Serine based head groups?
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they all have alcoholic bases
variety- serine, ethanolamine after decarboxylation, then choline after methylation of ethanolamine join with phopholipids to make phosphatidylserine, etc. Used to identify dead cells- phos-serine flips to the EC surface and is ingested by lysosomes |
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What is inositol and how is it used?
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Its a base head group
- six carbon cyclic sugar olcohol ring to make PI - can by substituted by phosphates for fun - act as secondary signals |
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What are some glycerol head groups?
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DAG, DPG
- cardiolipin is in the heart - 2- % of lipid protein is DPG dip-glycerol - affects ion exchange |
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What is the role of fatty acids in phospholipids? And describe.
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12-24 carbons, connected to glycerol by COOH group
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What are glycoglycerolipids?
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They are a glycolipid prominent in plants and prokaryotes
-Perform photosynthesis -contain sugars -hexoses connect to C3 glycerol on an O bond |
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What distinguishes sphingosine-based lipids?
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-a single amphipathic chain
-Amino group OH group -Formed from Serine -Precursor to ceramide |
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What is Ceramide
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-A sphingosine-based lipid
-Add another FA chain to the amine on a sphingosine - Intermediate state for a lipid |
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How do you make a sphingophospholipid?
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=Add a phosphate and a base to a ceramide off of a carbon.
- present in non-plant eukaryotes -brain and nerves EC membrane!!!! 6% of brain gray matter. used in blood |
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Why is asymmetry good?
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-differentiate the chemistry of the leaflets
-glycolipids=cerebrosides on outside -phosphatidlserine (-)! on the inside |
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What makes up 50% of membrane mass?
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Lipids! but depends...
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What kinds of sphingoglycolipids are there?
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-cerebrosides- 1 sugar
- globosides- more than one sugar -gangliosides- more than one sugar and also sialic acids |
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What disorder can cause Tay Sachs?
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sphingoglycolipid accumulation from being unable to break it down.
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What are sterols made of?
ROT |
-Rigid ring nucleus
-OH group or polar group -Tail of fatty acid. - only in eukaryotes, also in liver, RBC, low in ER. |
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What do sterols do?
ERGO - a yeast! A stigma for plants! lano before colo! |
- Change packing of phospholipds
- alter membrane transition temp - higher - reduce membrane permeability - make membrane more rigid |
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How can lipids move in the membrane?
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They can flip, go laterally, axially, and flip-flop.
Proteins can't flip! how stupid |
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What factors affect phase transition?
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-FA length. short = lower temp to gel, lower length enhances lateral diffusion, lower interaction.
- Double bonds in fatty acids - kinks make the lipid gel at a higher temp, unsaturated= good solid |
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How does cholesterol affect lipid packing?
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- Decrease fluidity but resist gel phasing
- rigidify the chain near the head group but increases rotation of the acyl chains further down -Reduce permeability to small solutes |
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Is the following prokaryote lipds or eukaryotes?
- synthesized at plasma membrane -Only one phospholip in the membrane - No sterol - Glycolipids come from glycerol |
prokaryote
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Eukaryotic or prokaryotic lipid?
Synthesized in ER -Mostly PC.PI,PE,PS, SM - neutral and negative phospholipids - contains sterols |
eukaryotic.
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