Lecture 8 DA

Question 1

What is the simplest phospholipid? Why is it important?

Answer 1

Phosphatidic acid. It is the precursor to other phospholipids.

Question 2

What is a triacylglycerol?

Answer 2

Lipid with three fatty acids esterified to a glycerol backbone.

Question 3

What is the main form of energy storage?

Answer 3

Triglycerides.

Question 4

Is the formation of lipid bilarys energetically favourable?

Answer 4

Yes.

Question 5

What is the energy content of triacylglycerides vs carbohydrates/proteins (kcal/g)?

Answer 5

Triacylglyceride - 9kcal/g

Protein/carb - 4kcal/g

Question 6

Why do triacylglycerides store mor energy vs carbohydrates or protein?

Answer 6

Carbohydrates and proteins are hydrated, making them more dense. Fat has little water around it and is more efficient.

Question 7

What are the fat soluble vitamins?

Answer 7

A, D, E, and K.

Question 8

How are triacylglycerides synthesised?

Answer 8

By elongating an acetyl CoA, and a primer with malonyl CoA.

Question 9

What are sphingolipids synthesised from?

Answer 9

Serine and long chain acyl CoA.

Question 10

What is the backbone of sphingolipids?

Answer 10

Sphenoid backbone.

Question 11

Where are sphingolipids found?

Answer 11

Nerves.

Question 12

What are saccharolipids, and where are they found?

Answer 12

Lipid with a sugar backbone, are compatible with the membrane.

Question 13

What is the shortest fatty acid in mammals?

Answer 13

Palmitic acid.

Question 14

What is the farthest desaturatable bond in fatty acids? What is a consequence of this?

Answer 14

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.

Question 15

What organism can make double bonds past the ninth bond?

Answer 15

Plants.

Question 16

Which two fatty acids cant be synthesised, and where do they come from?

Answer 16

Two essential fatty acids are linoleic acid and linolenic acid.
Linolenic comes from fish only, while linoleic comes from both plants and fish.

Question 17

Why do fish make linolenic acid?

Answer 17

To stop their membranes from being rigid due to fluctuating water temperatures.

Question 18

What is prostaglandin, and were is it made?

Answer 18

Its an eicosanoid, and made in almost all tissue.

Question 19

What kind of action does prostaglandin have, and does it have a long or short half life?

Answer 19

Short half life, it acts locally - paracrine.

Question 20

Do cells store prostaglandin?

Answer 20

No.

Question 21

What is prostaglandin made from?

Answer 21

Arachidonic acid.

Question 22

Aside from prostaglandin, what are two other eicosanoids? What are their effects, and how do they work?

Answer 22

Thromoxanes and leukotrienes. They act similar to ibuprofen/aspirin, which inhibit the enzyme cox2.
Eicosanoids also inhibit cox1, causing side effects.

Question 23

What are NSAIDs, and how do they work? Do they have side effects?

Answer 23

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.

Question 24

What are phospholipids made from?

Answer 24

Phosphatidic acid or diacylglycerol.

Question 25

What is used to provide energy for phospholipid synthesis?

Answer 25

CTP.

Question 26

What happens to synthesise phospholipids?

Answer 26

Polar head must be activated first, or hydrophilic tail of the diacylglycerol is activated first.

Question 27

What is the most abundant phospholipid in mammals? What is the second most abundant?

Answer 27

1. Phosphatidylcholine - lecithin. | 2. Phosphoethanolamine.

Question 28

How is phosphatidylserine made? Can mammals make it?

Answer 28

Head group exchange | Head groups are swapped. Mammals cant make it, must eat it.

Question 29

Can mammals make lecithin, phosphatidylethanolamine or phosphatidylserine?

Answer 29

No, but can convert the three between each other.

Question 30

Is transverse/vertical diffusion in cell membranes slow or fast? What does it require? What about lateral diffusion?

Answer 30

It is very slow, requires flippase enzymes. Lateral diffusion is very fast.

Question 31

Are the two membranes in a bilayer similar in terms of lipid population?

Answer 31

Not always, they can be very different, and often are.

Question 32

Which side of cell membranes do receptors point to?

Answer 32

They aim out.

Question 33

Where are embedded enzymes found in cell membranes?

Answer 33

They localise to one side.

Question 34

How are fats digested?

Answer 34

Bile is used to emulsify fat into micelles for digestion.

Question 35

What is bile?

Answer 35

Highly oxidised cholesterol.

Question 36

What is the use of pancreatic lipase? What are they specific to?

Answer 36

They digest fat, but only from 1 and 3 positions.

Question 37

What is needed for pancreatic lipase to bind?

Answer 37

Colipase.

Question 38

What is the starting point for ceramides?

Answer 38

Sphingosine.

Question 39

What is a ceramide?

Answer 39

Sphingosine molecule connected to a fatty acid by an amide bond.

Question 40

What is the starting point for sphingomyeline?

Answer 40

Ceramide.

Question 41

What is a sphingomyeline?

Answer 41

Ceramide with phosphorylcholine head group.

Question 42

Where is sphingomyeline found?

Answer 42

Myelin of nerves.

Question 43

What are cerebrosides and gangliosides?

Answer 43

Cerebroside - ceramide with some sugars. | Ganglioside - ceramide with many sugars.

Question 44

Where are chylomicrons formed, and where do they go?

Answer 44

Form in the gut, go to the liver.

Question 45

Where do VLDLs form, and where do they go?

Answer 45

Form in the liver, and go to the periphery.

Question 46

Where do LDLs and IDLs form, and where do they go?

Answer 46

Form in the periphery, and go to the liver.

Question 47

What are LDLs and IDLs the remnants of?

Answer 47

VLDL remnants.

Question 48

Where are the precursors of HDLs found? Where are HDLs themselves formed? Where do they go after?

Answer 48

Precursors made in the liver, HDLs made in the periphery. They go to the liver.

Question 49

Concerning fat, what effect does insulin and cAMP have?

Answer 49

Insulin - stores fat. | cAMP - releases fat.

Question 50

What do LDL receptors do, and where are they found?

Answer 50

Found in the liver, reabsorb lipoproteins.