Lipids

Question 1

What are 5 biological functions of lipids?

Answer 1

Storage of energy, membrane structure, signaling molecules, cofactors for enzymes, and antioxidants.

Question 2

Fatty acids with C10 or higher saturated hydrocarbon chains form…

Answer 2

Waxy solids at room temperature.

Question 3

Fatty acids with C9 or lower saturated or unsaturated hydrocarbon chains are…

Answer 3

Oily liquids at room temperature.

Question 4

The pKa of the COOH group is…

Answer 4

Less than 5

Question 5

At what pH are fatty acids fully ionized?

Answer 5

pH 7

Question 6

Most natural fatty acids…

Answer 6

Have an even number of carbons and are unbranched.

Question 7

Cis-double bonds affect…

Answer 7

The position o fatty acid tails, results in kinks or bends which equals less ordered packing.

Question 8

Unsaturated fatty-acids melting points are…

Answer 8

Lower

Question 9

Solubility and melting point of fatty acids are determined by…

Answer 9

Length of hydrocarbon chains and degree of saturation.

Question 10

All naturally occurring double bonds have…

Answer 10

Cis configuration.

Question 11

How do trans fatty acids form?

Answer 11

By partial hydrogenation of unsaturated fatty acids and cis-double bond isomerization to trans double bonds.

Question 12

When all fatty acids in a triglycerol are the same…

Answer 12

Simple tracylglycerides

Question 13

When the fatty acids in a triglycerol are different…

Answer 13

Complex triacylglycerides

Question 14

Triacylglycerols/Triglycerides

Answer 14

Glycerol + 3 fatty acids.

Storage lipid, neutral.

Question 15

Waxes

Answer 15

Storage lipid, non polar, do not contain glycerol.

Question 16

How are waxes formed?

Answer 16

By a condensation reaction between long fatty acids and alcohol hydrocarbon chains.

Question 17

Composition of glycerophospholipid

Answer 17

2 fatty acids and glycerol 3-phosphate backbone.

Question 18

What type of bond is formed between the phosphate group of glycerophospholipids and the carbon backbone chain?

Answer 18

Phosphodiester bond.

Question 19

What type of bond connects fatty acids and a carbon backbone (except in sphingolipids)?

Answer 19

Ester bonds.

Question 20

How are glycerophospholipids formed?

Answer 20

Condensation reaction between two fatty acids and the chiral carbon of glycerol 3-phosphate.

Question 21

Fatty acids linked to first hydroxyl in glycerophospholipids are generally…

Answer 21

Saturated.

Question 22

Fatty acids linked to second hydroxyl in glycerophospholipids are generally…

Answer 22

Unsaturated.

Question 23

Head group

Answer 23

Alcohol based compounds linked to phosphatidic acids.

Question 24

Sphingolipids are which type of lipid?

Answer 24

Structural, polar.

Question 25

Sphingolipids structure

Answer 25

Sphingosine backbone (long chain amino alcohol), a fatty acid at C2, and a polar head group.

Question 26

How is a fatty acid attached to the backbone of a sphingolipid?

Answer 26

Amide linkage.

Question 27

How are polar head groups connected to the sphingosine backbone of sphingolipids?

Answer 27

Phospho-ester linkage

Question 28

Sphingomeylin is classified as...

Answer 28

A phospholipid

Question 29

Glycosphingolipids determine...

Answer 29

Blood groups

Question 30

Gangliosides

Answer 30

Third group bonded to sphingosine chain in sphingolipids is a sugar.

Question 31

Phospholipases

Answer 31

Lipid specific enzymes that cleave ester linkages but not ethyl linkages.

Question 32

Biologically active lipids do not contain...

Answer 32

Fatty acids or glycerol backbone.

Question 33

Two major classes of biologically active lipids

Answer 33

Prostaglandins and steroids.

Question 34

How are prostaglandins generated?

Answer 34

Through modification of fatty acids.

Question 35

How are steroids generated?

Answer 35

From two carbon acids and modification of other sterols.

Question 36

What is cholesterol made up of?

Answer 36

Steroid nucleus, OH group and non polar branched side chain. Steroid nucleus is almost planar.

Question 37

Cholesterol prevents...

Answer 37

Close packing of lower ends of fatty acid tails. Decreases melting temp.

Question 38

Cholesterol promotes...

Answer 38

Tight packing of the upper ends of fatty acid tails. Increases melting temp.

Question 39

Cholesterol is known as...

Answer 39

The membrane fluidity buffer.

Question 40

3 structures of lipid aggregates

Answer 40

Lipid micelles, lipid bilayer and liposomes.

Question 41

Which lipids favour the lipid bilayer aggregate?

Answer 41

Phosphoacylglycerides and sphingolipids.

Question 42

What is the cell membrane impermeable to?

Answer 42

Charged ions, large molecules or proteins.

Question 43

What is the cell membrane permeable to?

Answer 43

Hydrophobic molecules and neutral gases and water.

Question 44

What can lipids do across the bilayer?

Answer 44

Diffuse laterally and spin on axis, but no uncatalyzed flip-flop motion allowed.

Question 45

What is main asymmetry?

Answer 45

Glycerophospholipids are oriented to the cytoplasm face.

Question 46

Flippase

Answer 46

Moves things from out to in.

Question 47

Floppase

Answer 47

Moves things from in the out.

Question 48

Scramblase

Answer 48

Moves lipids in either direction, towards equilibrium

Question 49

3 classes of membrane proteins

Answer 49

Integral/intrinsic membrane proteins, anchored membrane proteins and peripheral/associated membrane proteins.

Question 50

How are integral/intrinsic membrane proteins extracted?

Answer 50

With detergents.

Question 51

How are anchored membrane proteins extracted?

Answer 51

With detergent or phospholipases.

Question 52

How are peripheral/associated membrane proteins extracted?

Answer 52

With high pH buffers, denaturing agents and chelating agents.