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Biochem Exam 1 > Chapter 3 - Lipids > Flashcards

Chapter 3 - Lipids Flashcards

1
Q

What are the 2 major functions of lipids?

A
  1. Energy storage
  2. Membrane formation
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2
Q

What are 2 other functions of lipids?

A
  1. Form micelles
  2. Serve as signal molecules
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3
Q

What is the most prominent class of polar lipids?

A

Phospholipids

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4
Q

What are the building blocks of lipids?

A

Fatty Acids

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5
Q

What are the components of triglyceride (triacylglycerol)

A

3 fatty acids bonded to a glycerol

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6
Q

What are the 2 components in the structure of fatty acids

A

tail - hydrocarbon chain with a variable number of double bonds
head- typically a carboxyl group

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7
Q

In a fatty acid, which carbon is considered carbon number 1?

A

Carbon of the carboxyl group

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8
Q

What does the delta sign (little triangle) symbolize in a chemical formula for a fatty acid?

A

There is a double bond at that position

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9
Q

fatty acids containing double bonds are considered _____

A

unsaturated

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10
Q

What does the term polyunsaturated mean?

A

When more than one double bond exists in a fatty acid

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11
Q

Double bonds in fatty acids can either be ___ or ____. Which one produces a kink in the chain?

A

cis, trans.
cis

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12
Q

Cis fatty acids have a ______melting point than trans.

A

lower

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13
Q

Can carbon-carbon single or double bonds rotate freely around their bond axis??

A

single

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14
Q

Are cis fatty acids liquid or solid?

A

liquid

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15
Q

Are conjugated or isolated double bonds more reactive

A

isolated. conjugated are stabilized by resonance (electrons are delocalized)

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16
Q

Polyunsaturated fatty acids always have ______ double bonds

A

isolated

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17
Q

Why is the head of a fatty acid so soluble in water?

A

COOH is a weak acid, so it is almost always in its anionic form (COO-)

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18
Q

What is the term to describe that fatty acids have both a hydrophilic/phobic part?

A

amphipathic

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19
Q

Which fatty acid is the most common in mammals and is an energy storage form

A

Triglyceride (triacylglycerol)

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20
Q

An ester bond describes the bond between…..?

A

Fatty acid and glycerol

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21
Q

Triglycerides are formed by..

A

dehydration synthesis

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22
Q

Are triacylglycerols hydrophilic or hydrophobic? why?

A

Hydrophobic - the ester bond is not able to form H bonds with water
-O-

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23
Q

Why is it a benefit for triglycerides to be hydrophobic?

A

Excluding water reduces the weight of the fat cells

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24
Q

Animals use _____
Plants use _____

A

Animals use lipids
Plants use carbohydrates

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25
Q

Molecularly - why do carbohydrates weigh more than lipids?

A

Many more oxygen molecules in carbohydrates

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26
Q

What is visceral fat?

A

Triglycerides with saturated side chains. Solid fat that is deposited near organs

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27
Q

Less saturated side chains are a fat called _________. Where are they found?

A

subcutaneous fat. Just under the skin

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28
Q

Even more unsaturated triglycerides are known as _______. They are found in seeds

A

oils

29
Q

What are the molecular components of phospholipids?

A

2 fatty acids and a phosphate group bonded to glycerol

30
Q

Phopshate is a polyprotic acid meaning what?? This makes it a good _____

A

Phosphate can donate more than one proton. It has multiple equilibria.This makes it a good buffer

31
Q

Phosphates are derivatives of….?

A

Phosphatidic acid

32
Q

Inorganic Phosphate is a ____acid

A

weak

33
Q

Phosphate reacts with _____s to form _______s

A

phosphate reacts with alcohol to form esters

34
Q

Phosphates have a lot of variability. They can form _____ and attach to all different kinds of alcohols and fatty acids.

A

diesters

35
Q

Cholesterol is a ______

A

steroid

36
Q

Steroids are _____

A

lipids

37
Q

Cholesterol consists of…

A

4 fused, flat rings and a hydroxyl group

38
Q

Is cholesterol hydrophobic or hydrophilic?

A

mostly hydrophobic

39
Q

Give 3 examples of amphipathic molecules

A

fatty acids
cholesterol
phospholipids

40
Q

Amphipathic molecules will form either _____ or _____

A

micelles or liposomes

41
Q

What is a micelle?

A

Polar portions face the aqueous exterior. Nonpolar portion forms an interior core excluded from water.

42
Q

Fatty acids form ______ in water

A

micelles

43
Q

Name 3 steroid derivatives of cholesterol

A

Testosterone, estradiol, aldosterone

44
Q

Amphipathic molecules have 2 conflicting natures. What are they?

A

Water solubility and lipid solubility

45
Q

What does CMC stand for and explain what it means

A

CMC = critical micelle concentration. This value is the concentration at which fatty acids form micelles

46
Q

The higher the CMC of a substance, the ____ soluble it is in water

A

more

47
Q

When fatty acids are added beyond the CMC, new micelles are formed but the concentration of free fatty acids in the water solution remains ______

A

constant

48
Q

CMC depends strongly on ________ such as ______

A

CMC depends strongly on experimental conditions such as salt concentration

49
Q

Liposomes consist of 3 layers. What are they?

A
  1. Exterior water phase
  2. Interior water phase
  3. Non polar phase between
50
Q

Essentially, liposomes form a _______

A

biological membrane - a bilayer

51
Q

How can you determine if a micelle or liposome will form?

A

If the volumes of the hydrophilic and hydrophobic portions are unequal, a micelle will form. If the volumes are equal, a liposome will form

52
Q

Phophatidylcholine is a major component of the _______

A

cell membrane

53
Q

Phosphatidylcholine forms a ______ in water

A

liposome

54
Q

Can water readily cross the cell membrane?? Why??

A

Yes - because of the extremely large concentration of water

55
Q

In general, can hydrophilic substances cross the cell membrane?

A

NO

56
Q

What are aquaporins?

A

Protein channels that can accelerate or regulate the flow of water through the cell membrane

57
Q

Because of the composition of a membrane, what can exist on either side?

A

2 solutions with distinct composition

58
Q

What is diffusion?

A

The movement of substances due to differences in concentration

59
Q

What is osmosis?

A

Movement of water across a semipermeable membrane from a region of low concentration to a region of high concentration

60
Q

Do double bonds in fatty acid chains decrease or increase membrane fluidity?

A

increase

61
Q

At low temperatures, cholesterol ______ the fluidity of the cell membrane

A

increases

62
Q

At high temperatures, cholesterol ________ the fluidity of the cell membrane

A

decreases

63
Q

Give another example of a lipid aside from triacylglycerol, phospholipids, and sterols

A

lipopolysaccharide - lipid + sugar

64
Q

In naturally occurring fatty acids, the double bonds are in the ______ conformation

A

cis

65
Q

Unsaturated fatty acid tails are more hydrophobic or hydrophilic?

A

hydrophilic

66
Q

Long fatty acid tails are more/less soluble in water than short tails

A

less

67
Q

What are the 3 major types of lipids

A
  1. Phospholipids
  2. Triglycerides
  3. sterols
68
Q

Why do single bonds not possess cis/trans stereochemistry?

A

They can rotate

69
Q

Whose melting temperature is higher at the same molecular weight? (saturated or unsaturated fatty acids)

A

saturated fatty acids (double bonds change shape. single bonds are more well packed)

Biochem Exam 1 (7 decks)

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