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Biochemistry I > Lipids > Flashcards

Lipids Flashcards

1
Q

What are 5 biological functions of lipids?

A

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

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2
Q

Fatty acids with C10 or higher saturated hydrocarbon chains form…

A

Waxy solids at room temperature.

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3
Q

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

A

Oily liquids at room temperature.

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4
Q

The pKa of the COOH group is…

A

Less than 5

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5
Q

At what pH are fatty acids fully ionized?

A

pH 7

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6
Q

Most natural fatty acids…

A

Have an even number of carbons and are unbranched.

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7
Q

Cis-double bonds affect…

A

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

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8
Q

Unsaturated fatty-acids melting points are…

A

Lower

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9
Q

Solubility and melting point of fatty acids are determined by…

A

Length of hydrocarbon chains and degree of saturation.

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10
Q

All naturally occurring double bonds have…

A

Cis configuration.

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11
Q

How do trans fatty acids form?

A

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

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12
Q

When all fatty acids in a triglycerol are the same…

A

Simple tracylglycerides

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13
Q

When the fatty acids in a triglycerol are different…

A

Complex triacylglycerides

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14
Q

Triacylglycerols/Triglycerides

A

Glycerol + 3 fatty acids.

Storage lipid, neutral.

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15
Q

Waxes

A

Storage lipid, non polar, do not contain glycerol.

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16
Q

How are waxes formed?

A

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

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17
Q

Composition of glycerophospholipid

A

2 fatty acids and glycerol 3-phosphate backbone.

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18
Q

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

A

Phosphodiester bond.

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19
Q

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

A

Ester bonds.

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20
Q

How are glycerophospholipids formed?

A

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

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21
Q

Fatty acids linked to first hydroxyl in glycerophospholipids are generally…

A

Saturated.

22
Q

Fatty acids linked to second hydroxyl in glycerophospholipids are generally…

A

Unsaturated.

23
Q

Head group

A

Alcohol based compounds linked to phosphatidic acids.

24
Q

Sphingolipids are which type of lipid?

A

Structural, polar.

25
Q

Sphingolipids structure

A

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

26
Q

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

A

Amide linkage.

27
Q

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

A

Phospho-ester linkage

28
Q

Sphingomeylin is classified as…

A

A phospholipid

29
Q

Glycosphingolipids determine…

A

Blood groups

30
Q

Gangliosides

A

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

31
Q

Phospholipases

A

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

32
Q

Biologically active lipids do not contain…

A

Fatty acids or glycerol backbone.

33
Q

Two major classes of biologically active lipids

A

Prostaglandins and steroids.

34
Q

How are prostaglandins generated?

A

Through modification of fatty acids.

35
Q

How are steroids generated?

A

From two carbon acids and modification of other sterols.

36
Q

What is cholesterol made up of?

A

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

37
Q

Cholesterol prevents…

A

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

38
Q

Cholesterol promotes…

A

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

39
Q

Cholesterol is known as…

A

The membrane fluidity buffer.

40
Q

3 structures of lipid aggregates

A

Lipid micelles, lipid bilayer and liposomes.

41
Q

Which lipids favour the lipid bilayer aggregate?

A

Phosphoacylglycerides and sphingolipids.

42
Q

What is the cell membrane impermeable to?

A

Charged ions, large molecules or proteins.

43
Q

What is the cell membrane permeable to?

A

Hydrophobic molecules and neutral gases and water.

44
Q

What can lipids do across the bilayer?

A

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

45
Q

What is main asymmetry?

A

Glycerophospholipids are oriented to the cytoplasm face.

46
Q

Flippase

A

Moves things from out to in.

47
Q

Floppase

A

Moves things from in the out.

48
Q

Scramblase

A

Moves lipids in either direction, towards equilibrium

49
Q

3 classes of membrane proteins

A

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

50
Q

How are integral/intrinsic membrane proteins extracted?

A

With detergents.

51
Q

How are anchored membrane proteins extracted?

A

With detergent or phospholipases.

52
Q

How are peripheral/associated membrane proteins extracted?

A

With high pH buffers, denaturing agents and chelating agents.

Biochemistry I (10 decks)

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