Lecture 22 Flashcards

1
Q

Why are fatty acids amphiphilic?

A

Because of the carboxylate and the hydrocarbon

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2
Q

What is the hydrophilic end of a fatty acid?

A

The carboxylate with a negative charge at pH 7

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3
Q

What is the Hydrophobic end of a fatty acid?

A

The hydrocarbon chain portion

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4
Q

In what configuration are most of the double bonds in fatty acids?

A

They exist in the cis/Z configuration

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5
Q

What is a monounsaturated fatty acid?

A

One that contains a single double bond

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6
Q

What is a polyunsaturated fatty acid?

A

One that contains many double bonds

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7
Q

What does it say about the pka of fatty acids if they carry a negative charge at pH 7?

A

The pH is greater than the pka in that functional group and it is in the base form. And the pka is less than 7

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8
Q

What conformation are most naturally occuring double bond in?

A

The cis conformation

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9
Q

What properties does the cis conformation affect?

A

Melting point

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10
Q

How does cis conformation affect melting point?

A

It lowers melting point making it melt a lower temperature

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11
Q

How do cis double bonds affect physical structure?

A

It introduces kinks or bends into the overall structure

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12
Q

Which carbon do you start counting from when counting the number of carbons in a fatty acid?

A

The carbon in the carboxyl group is alway the first carbon

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13
Q

What is carbon number two in a fatty acid chain?

A

The carbon that is attached to a carboxyl group

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14
Q

What is the ɑ carbon in a fatty acid?

A

The carbon that is attached to the carboxyl group within the fatty acid. Usually carbon 2

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15
Q

What is the greek letter designation of carbon number three in fatty acid chains?

A

It is the β carbon

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16
Q

What is the beta carbon in fatty acids?

A

It is the third carbon in a fatty acid

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17
Q

What does beta oxidation have to do with?

A

The oxidation of the beta carbon in a fatty acid

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18
Q

What is the greek letter designation of the very last carbon of a fatty acid?

A

It is the omega carbon

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19
Q

What is the ɷ carbon?

A

The very last carbon in a fatty acid chain

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20
Q

What is the shorthand notation for describing fatty acids?

A

(# of carbons):(# of double bonds)𝛥(locations of double bonds separated by commas)

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21
Q

What configuration is the double bond assumed to be unless otherwise stated in shorthand fatty acid notation?

A

They are assumed to cis unless it says trans

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22
Q

How does a double bond physically affect a hydrocarbon chain?

A

It introduces a bend in the hydrocarbon chain

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23
Q

What is the preferred conformation of fatty acids?

A

The conformation that gets the carbons as far away from each other as possible to create a low energy structure

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24
Q

What kind of aspect does a double bond introduce into a fatty aicd structure?

A

A rigid aspect

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25
Q

How do double bonds affect degrees of freedom?

A

It creates less degrees of freedom

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26
Q

What do bends in fatty acids impact?

A

How well the molecules stack together and their melting point and general behavior

27
Q

What is the state of most saturated fatty acids at room temperature?

A

They are usually solids because their fatty acids stack together

28
Q

What is the general behavior of melting points of saturated fatty acids?

A

They generally have higher melting points and are solid at room temperature

29
Q

How is melting point affected by length of a fatty acid?

A

As length increases melting point increases

30
Q

What is the difference between melting point of a short fatty acid and a long fatty acid?

A

As the length increases the melting point of the fatty acid increases. So a longer fatty acid will have a higher melting point than a shorter fatty acid

31
Q

How do double bonds affect Melting Points of fatty acids?

A

Increasing double bonds will decrease melting point causing them to be liquid at room temp

32
Q

What is the most important at determining melting point of fatty acids?

A

Length is important but saturation is most important. Length increases melting point and double bonds decrease melting point

33
Q

How does the degree of unsaturation affect melting point?

A

The greater the degree of unsaturation (meaning more double bonds) the lower the melting point

34
Q

What two things affect fatty acid melting points?

A

Length and unsaturation

35
Q

Which length of fatty acids melt at higher temperatures?

A

Longer fatty acids melt at higher temperatures

36
Q

Which saturation of fatty acids melt at higher temperatures?

A

Saturated fatty acids melt at higher temperatures

37
Q

How does saturation effect packing of fatty acids?

A

Unsaturated fatty acids cannot pack together effectively

38
Q

What are the van der walls interactions like in saturated and unsaturated fatty acids?

A

Saturated fatty acids are able to align closely and minimize van der waals interactions. Unsaturated fatty acids cannot pack together closely because of the bend

39
Q

What is the difference in packing between trans and cis fatty aicds?

A

Trans fatty acids don’t introduce kinks so they are able to pack together more

40
Q

What is one of the ways that the body stores fats?

A

In triacylglycerols

41
Q

What is the phobicity of TAG?

A

They are very hydrophobic (not amphipathic)

42
Q

What is the structure of Triacylglycerol?

A

They are three acyl chains attached to glycerol

43
Q

What is the difference in melting points between trans and cis fatty acids?

A

Trans fatty acids have higher melting points than cis melting point because they do not have the kinks that cis fatty acids have

44
Q

What kind of linkage links the acyl to the glycerol?

A

An ester linkage

45
Q

Which triacylglycerols will have lower melting points?

A

Those containing fatty acids or shorter chains

46
Q

What type of TAGs are most common?

A

Mixed TAGs so they have a mixture of saturated and unsaturated chains

47
Q

What are the three types of Membrane li[ids?

A
  • Glycerophospholipids
  • Sphingolipids
  • Cholesterol
48
Q

Which membrane lipids include fatty acids as part of their structure?

A
  • Glycerophospholipids

* Sphingolipids

49
Q

What is the structure of Glycerophospholipids?

A

A fatty acyl group covalently attached to a glycerol

50
Q

What makes Glycerophospholipids Amphipathic?

A

The presence of a large polar group

51
Q

How many acyl chains is the Glycerol attached to in Glycerophospholipids?

A

It is attached to two acyl chains

52
Q

What is the glycerol is Glycerophospholipids attached to?

A

Two acyl chains and a polar head group usually a phosphate group

53
Q

What is the polarity of each part of Glycerophospholipids?

A

The phosphate head is polar and the two acyl tails are nonpolar

54
Q

What do Glycerophospholipids by themselves usually form?

A

A bilayer or membrane structure

55
Q

What do fatty acids usually form?

A

Micelles

56
Q

What is the polarity of Cholesterol?

A

It is weakly amphipathic

57
Q

What is the flexibility of Cholesterol and why?

A

It is very rigid because of it ring structure

58
Q

What cause cholesterol to be weakly amphipathic?

A

Its small -OH group

59
Q

How much of mammalian plasma membranes does cholesterol form?

A

Around 30%

60
Q

What does each part of cholesterol associate with in the membrane?

A
  • OH associates with polar headgroup of other lipids

* Non-polar portion is found in the membrane

61
Q

What is the function of cholesterol in membranes?

A

It is important for the melting point behaviors. Maintains Fluidity and rigidity

62
Q

What do fatty acids tend to form in an aqueous environment?

A

Micelles

63
Q

What do membrane lipids tend to form in an aqueous environment?

A

They form a bilayer

64
Q

Why do Micelles or Bilayers form?

A

To limit unfavorable contact between water and H2O and hydrophobic tails and still permit solvation of polar head groups