Lipids - Structure Flashcards

1
Q

Why are lipids classified
differently from
carbohydrates and proteins?
On what basis are lipids
classified?

A

-They are structurally and functionally diverse

-Tends to be water soluble
-dissolve in solvents (alcohol, acetone, ether)

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2
Q

What are amphipathic
lipids?

A

Lipids that are both hydrophobic and hydrophillic

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3
Q

What are the components of
triglycerides, diglycerides,
and monoglycerides?

A

Tri: Glycerol + 3 Fatty Acids
Di: Glycerol + 2 Fatty Acids
Mono: glycerol + 1 Fatty Acid

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4
Q

(1)What is the structure of a phospholipid. (2)What is it classified as?

A

1 - Glycerol + 2 fatty acids + phosphate group

2- amphipathic

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5
Q

What type of lipid is similar to phospholipids?

A

Triglycerides

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6
Q

Which parts of the phospholipids are hydrophobic and hydrophillic?

A

Hydrophillic = phosphate head
Hydrophobic = fatty acids

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7
Q

What do cell membranes consist of?

A

2 layers of phospholipids

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8
Q

How do the layers of phospholipids function in cell membrane

A

Polar head: oriented towards intracellular & extracellular fluid

Nonpolar fatty acids: oriented inwards, away from intracellular & extracellular fluid

intra = inside cell
extra = outside cell

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9
Q

(1)What do phospholipids form? (2) What is its function?

A

1 - lipoproteins
2 - complexes that transport insoluble lipids in blood

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10
Q

How do phospholipids function in bile?

A

Aids in lipid digestion by emulsifying dietary lipids into lipid droplets.

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11
Q

What is the basis of
determining if a
nutrient is classified as a
lipid?

A
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12
Q

Describe the structure
of triglycerides and
phospholipids.

A

Triglyceride= glycerol + 3 FA

Phopholipids = glycerol + 2 FA + phosphate head

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13
Q

What makes
phospholipids
amphipathic?

A
  1. Hydrophillic polar phosphate head
  2. Hydophobic fatty acid tails
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14
Q

What functions do
phospholipids have in
the body?

A

Form lipoproteins that transport insoluble lipids around body. In bile they assist in protein digestion.

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15
Q

What is cholesterol?

A

The most abundant sterol in the body madeby the liver(not an energy source)

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16
Q

What are the functions
of cholesterol in the
body?

A

1 - important component of cell membranes
2 - Parent compounds used to make other sterols
3 - Nonessential nutrient

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17
Q

Why is cholesterol important for cell membranes?

A

Maintain stability and fluidity

18
Q

What sterols do cholesterol form?

A

Vitamin D, Cortisol, reproductive hormones

19
Q

Where is cholesterol made

A

liver

20
Q

Describe the structure
of a generic fatty acid

A

Carbon-hydrogen-oxygen with an acid group (COO) group at one end and methyl group (CH3) on the other.

21
Q

In what ways do fatty
acids differ?

A

1) C=C vs C-C (type of carbon bond)

2) # carbons in the chain (short/medium/long fatty acid chain)

3) Essential and Nonessential

22
Q

How does carbon chain length affect the fatty acid?

A

Shorter chain = more soluble

23
Q

What makes a fatty acid
a saturated vs. an
unsaturated fatty acid?

A

Saturated: C-C and contain the max. number of H-atoms
Unsaturated: C=C and have 2 or less H-atoms with equal number of C-atoms

24
Q

What are the types of unsaturated fatty acids and how do they differ?

A

1) Monosaturated = one double bond
2) polyunsaturated = 2 or more double bonds

25
Q

How does the fatty acid
composition of a food
influence its physical
property? Fats vs. oils

A

-Proportion of saturated to unsaturated fatty acids in food determines whether solid or liquid at room temp (fat or oil)

26
Q

Fats vs. Oils

A

Fats: Solid at room temp (b/c high % saturated fatty acids)
Oils: Liquid at room temp (b/c high % unsaturated fatty acids)

27
Q

Why does unsaturation/saturation influence physical properties?

A

SFA: Pack closely together in an orderly array = solid at room temp
UFA: Have bends and kinks that prevent close orderly packing = liquid at room temp

28
Q

How are fatty acids named?

A

of carbon bonds, # double bonds, position of double bonds

29
Q

What makes a fatty acid
is essential or
nonessential? What are
the 2 essential FA?

A

Essentially based on the position of the first double bond from the methyl end.

Essential = 1st double bond occurs BEFORE 9th C-atom

30
Q

Why can’t the body digestion essential fatty acids?

A

Humans lack the enzymes needed to synthesize double bonds occurring before C-9

31
Q

Describe the omega
system nomenclature

A

omega-n system = number of the carbon atom with the first double bond from the methyl end.

32
Q

What are the 2 essential fatty acids?

A

1) Linolenic Acid: 18:3 omega-3 FA (walnuts/flaxseed oil/fortified foods/fatty fish)

2) Linoleic Acid: 18.2 omega-6 FA (seeds, nuts, seed oils)

33
Q

How are essential FA
used to make other
omega-3 and omega-6
FAs?

A

They are parent compounds used to make other omega-3 and omega-6 fatty acids.

34
Q

What does elongation
and desaturation do to a
FA?

A

Elongation: increase length of the C-chain by addition of C-atoms

Desaturation: Increase # of double bonds by removal of H-atoms

35
Q

3 types of fatty acids formed from elongation and desaturation:

A

Arachiodnic acid (AA): Linoleic Acid 18:2 omega-6 + 4 C-atoms + 2 double bonds

Eicosapentaenoic acid (EPA): Linoleic Acid 18:3 omega-3 + 2 C-atoms + 2 double bonds

Docosahexaenoic acid (DHA): +2 C-atoms + 1 double bonds

36
Q

How do you increase EPA and DHA in the body?

A

Dietary/supplementation

37
Q

Why is dietary/supplementation the best way of increasing EPA and DHA in the body?

A

EPA and DHA can be synthesized but the conversion is slow and limited.

38
Q

Why is DHA important
to health (3)?

A

(1) Lower cardiovascular disease risk
(2) Brain + eye development in fetus
(3) Brain development throughout infancy

39
Q

In what foods are DHA found?

A

1 - Oily, dark fishes (salmon, tuna, mackerel, herring, sardines have high mercury)

40
Q

How is DHA important for mothers?

A

Developmentof fetus