Chp 10: Short Answer

Question 0

Dependence of melting point of a fatty acid on unsaturation:

Answer 0

More unsaturation, the lower the Tm

Question 1

Dependence of melting point of a fatty acid on chain length

Answer 1

Longer the chain, higher the Tm

Question 2

Explain Tm dependencies in molecular terms:

Answer 2

More chain length= more hydrophobic inxns; less saturation= more double bonds= more kinks= harder packing upon crystallization

Question 3

Effect of a double bond on fatty acid structure

Answer 3

Double bonds are cis, and this reaults in a rigid bend in the hydrocarbon chain

Question 4

What is the molecule to which fatty acids are esterified to form triacylglycerols?

Answer 4

Three fatty acids are esterified to glycerol

Question 5

Why do cells store fatty acids in their esterified form?

Answer 5

Triacylglycerols are uncharged and insoluble in water. They form lipid droplets which do not contribute to osmolarity of the cytosol and do not require hydration

Question 6

Most significant difference between triacylglycerols and glycerophospholipids:

Answer 6

Triacylglycerols are nonpolar and hydrophobic that can be stored in nonaqueous cellular compartments. Glycerophospholipids are amphipathic and can be in membranes

Question 7

3 functions of triacylglycerols in mammals and one in higher plants:

Answer 7

Animals: stored fuel, insulation, source of metabolic water. Plants: oxidation of triacylglycerols provides germination energy before photosynthesis can be used as a source of energy

Question 8

What are the chemical components of a biological wax, what is their general structure?

Answer 8

Long-chain fatty acid in ester linkage with a long-chain fatty alcohol (draw structure)

Question 9

What chemical features distinguish a plasmologen from a common glycerophospholipid?

Answer 9

1) long-chain acyl group attached to C1 of glycerol is ether linked in pl. but is an ester linked fatty acyl group in gp. 2) double bond btwn C1-C2 in pl. but not gp.

Question 10

Function of prostoglandin:

Answer 10

Mediate pain and inflammation

Question 11

Function of sphingolipids:

Answer 11

Component of myelin membranes

Question 12

Function of thromboxanes:

Answer 12

Blood clotting

Question 13

Function of vitamin A:

Answer 13

Sight

Question 14

Biological role of Vitamin K:

Answer 14

Blood clotting

Question 15

Biological role of Vitamin D:

Answer 15

Calcium and phosphate metabolism

Question 16

Biological role of Vitamin E:

Answer 16

Prevention of oxidative damage

Question 17

What is an isoprenoid compound and give an example:

Answer 17

They contain chains that consist of multiple isoprene units (look up an example)

Question 18

What do Vitamins A, K, ubiqionone, and dolichol have in common?

Answer 18

Lipids with potent biological activities that are derived from isoprenoid precursors

Question 19

Why does extraction of lipids from tissues require organic solvents?

Answer 19

Lipids are either strongly hydrophobic or amphipathic. Because tissues are in water, lipids are present in aggregates. The aggregates don’t occur in organic solvents, and thus the lipids are more soluble in organic solvents and are easier to extract from tissues

Question 20

If beeswax, cholesterol, and phosphatidylglycerol were dissolved in chloroform, then subjected to thin-layer chromatography on silica gel using chloroform/methanol/water as the developing solvent, which would move fastest?

Answer 20

Least polar compound (beeswax) moves fastest, most polar compound (phosphatidylglycerol) moves slowest