Lecture 8 DA Flashcards
What is the simplest phospholipid? Why is it important?
Phosphatidic acid. It is the precursor to other phospholipids.
What is a triacylglycerol?
Lipid with three fatty acids esterified to a glycerol backbone.
What is the main form of energy storage?
Triglycerides.
Is the formation of lipid bilarys energetically favourable?
Yes.
What is the energy content of triacylglycerides vs carbohydrates/proteins (kcal/g)?
Triacylglyceride - 9kcal/g
Protein/carb - 4kcal/g
Why do triacylglycerides store mor energy vs carbohydrates or protein?
Carbohydrates and proteins are hydrated, making them more dense. Fat has little water around it and is more efficient.
What are the fat soluble vitamins?
A, D, E, and K.
How are triacylglycerides synthesised?
By elongating an acetyl CoA, and a primer with malonyl CoA.
What are sphingolipids synthesised from?
Serine and long chain acyl CoA.
What is the backbone of sphingolipids?
Sphenoid backbone.
Where are sphingolipids found?
Nerves.
What are saccharolipids, and where are they found?
Lipid with a sugar backbone, are compatible with the membrane.
What is the shortest fatty acid in mammals?
Palmitic acid.
What is the farthest desaturatable bond in fatty acids? What is a consequence of this?
The ninth bond from the α carbon. Mammals cant make double bonds in the last 6 bonds. Making longer fatty acids needs to be ingested.
What organism can make double bonds past the ninth bond?
Plants.
Which two fatty acids cant be synthesised, and where do they come from?
Two essential fatty acids are linoleic acid and linolenic acid.
Linolenic comes from fish only, while linoleic comes from both plants and fish.
Why do fish make linolenic acid?
To stop their membranes from being rigid due to fluctuating water temperatures.
What is prostaglandin, and were is it made?
Its an eicosanoid, and made in almost all tissue.
What kind of action does prostaglandin have, and does it have a long or short half life?
Short half life, it acts locally - paracrine.
Do cells store prostaglandin?
No.
What is prostaglandin made from?
Arachidonic acid.
Aside from prostaglandin, what are two other eicosanoids? What are their effects, and how do they work?
Thromoxanes and leukotrienes. They act similar to ibuprofen/aspirin, which inhibit the enzyme cox2.
Eicosanoids also inhibit cox1, causing side effects.
What are NSAIDs, and how do they work? Do they have side effects?
Non-steroidal anti-inflammatory drugs.
All inhibit prostaglandin production. Some selectively inhibit cox2, less side effects on the GI tract.
Higher cardiovascular risk, some cause ulcers.
What are phospholipids made from?
Phosphatidic acid or diacylglycerol.
What is used to provide energy for phospholipid synthesis?
CTP.
What happens to synthesise phospholipids?
Polar head must be activated first, or hydrophilic tail of the diacylglycerol is activated first.
What is the most abundant phospholipid in mammals? What is the second most abundant?
- Phosphatidylcholine - lecithin.
2. Phosphoethanolamine.
How is phosphatidylserine made? Can mammals make it?
Head group exchange
Head groups are swapped. Mammals cant make it, must eat it.
Can mammals make lecithin, phosphatidylethanolamine or phosphatidylserine?
No, but can convert the three between each other.
Is transverse/vertical diffusion in cell membranes slow or fast? What does it require? What about lateral diffusion?
It is very slow, requires flippase enzymes. Lateral diffusion is very fast.
Are the two membranes in a bilayer similar in terms of lipid population?
Not always, they can be very different, and often are.
Which side of cell membranes do receptors point to?
They aim out.
Where are embedded enzymes found in cell membranes?
They localise to one side.
How are fats digested?
Bile is used to emulsify fat into micelles for digestion.
What is bile?
Highly oxidised cholesterol.
What is the use of pancreatic lipase? What are they specific to?
They digest fat, but only from 1 and 3 positions.
What is needed for pancreatic lipase to bind?
Colipase.
What is the starting point for ceramides?
Sphingosine.
What is a ceramide?
Sphingosine molecule connected to a fatty acid by an amide bond.
What is the starting point for sphingomyeline?
Ceramide.
What is a sphingomyeline?
Ceramide with phosphorylcholine head group.
Where is sphingomyeline found?
Myelin of nerves.
What are cerebrosides and gangliosides?
Cerebroside - ceramide with some sugars.
Ganglioside - ceramide with many sugars.
Where are chylomicrons formed, and where do they go?
Form in the gut, go to the liver.
Where do VLDLs form, and where do they go?
Form in the liver, and go to the periphery.
Where do LDLs and IDLs form, and where do they go?
Form in the periphery, and go to the liver.
What are LDLs and IDLs the remnants of?
VLDL remnants.
Where are the precursors of HDLs found? Where are HDLs themselves formed? Where do they go after?
Precursors made in the liver, HDLs made in the periphery. They go to the liver.
Concerning fat, what effect does insulin and cAMP have?
Insulin - stores fat.
cAMP - releases fat.
What do LDL receptors do, and where are they found?
Found in the liver, reabsorb lipoproteins.
