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Macronutrients > Exam #3 > Flashcards

Exam #3 Flashcards

1
Q

Simple Lipids

A
  1. ) Fatty Acids
  2. ) Triacylglycerols, diacylglycerols, and monoacylglycerols
  3. ) Waxes (esters of fatty acids with higher alcohols)
    includes: sterol esters (cholesterol - fatty acid esters) and nonsterol esters (vitamin A esters)
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2
Q

Compound Lipids

A

1.) Phospholipids

Includes: Phosphatidic acids, Plasmalogens, Sphingomyelins

  1. ) Glycolipids (CHO containing)
  2. ) Lipoproteins (lipids associated with protein)
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3
Q

Lipids in Human Nutrition

A

Fatty Acids

Triacylglycerols

Sterols & Steroids

Phospholipids

Glycolipids

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4
Q

Fatty Acids

A

Simplest of lipids

Straight hydrocarbon chain

polar hydophilic end (carboxyl group) terminating end

nonpolar hydrophobic end (methyl group) insoluble

important energy nutrient furnishing most of the calories from dietary fat

chains vary from 4 (butyric acid) to 24 carbon atoms

Functional Groups makes 2 things possible:

  1. ) attach to other things (ie glycerol and protein)
  2. ) hydrophilic likes water

Most FA have an even number of carbon atoms - this is because building block Actyl CoA (2C)

Odd-numbered FAs do occur naturally to some extent (seafood)

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5
Q

Cis Isomerism

A

unsaturated

folding back and kinking

U like orientation

most naturally occurring

Hydrogens on adjacent Cs attached by double bond are either both up or both down (same side)

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6
Q

Trans Isomerism

A

unsaturated

extending molecule into linear shape similar to that of saturated fatty acids

partially hydrogenated fats and oils

margarine and frying oils designed to be solids at room temp

trans= 1H up and 1H down on adjacent carbons (more straight) (opposite sides)

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7
Q

Delta Nomenclature

A

Ex: 18:2 Δ9,12 linoleic acid

18 = 18 carbons

2 = 2 double bonds

9,12 = carbon atoms at which double bond begins (numbering starts from carboxyl end)

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8
Q

Omega Nomenclature

A

Ex: 18:2 n-6 linoleic acid

18 = 18 carbon atoms

2 = 2 double bonds

n-6 = loaction of carbon atom of the first double bond (starts counting from the methyl end)

** Takes into account that double bonds in a fatty acid are always separted by 3 carbons**

omega 6 = 2 double bonds

omega 3 = 3 double bonds

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9
Q

Saturated Fatty Acid

A

SFA

contains no double bonds

packs a lot of lipids in a small space packaged well

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10
Q

Palmitic Acid

A

saturated fatty acid

16Cs with no double bonds (16:0)

animal and plant fats

CH3-(CH2)14-COOH

Fatty Acid Synthesis: glucose->fat make palmitic acid first

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11
Q

Stearic Acid

A

saturated - solids at room temp

18C length no double bonds (18:0)

animal fats (beef), and some plant fats

CH3-(CH2)16-COOH

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12
Q

Monounsaturated

A

MUFA

possessing one carbon-carbon double bond

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13
Q

Palmitoleic Acid

A

Monounsaturated fatty acid

16Cs and 1 double bond (16:1Δ9 (n-7))

marine animal oils, small amt of plant and animal fats

CH3-(CH2)5-CH=CH-(CH2)7-COOH

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14
Q

Oleic Acid

A

unsaturated fatty acid

18Cs and 1 double bond (18:1)

plant and animal fats

CH3-(CH2)7-CH=CH-(CH2)7-COOH

olive oil (usually oils are mixtures oleic is found in a lot of stuff)

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15
Q

Polyunsaturated

A

PUFA

have two or more carbon-carbon double bonds

may have as many as 6 double bonds

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16
Q

Linoleic Acid

A

polyunsaturated fatty acid

18Cs 2 double bonds (18:2Δ9,12 (n-6))

corn, safflower, soybean, cottonseed, sunflower seed, and peanut oil

CH3-(CH2)4-CH=CH-CH2-CH=CH-(CH2)7-COOH

essential fatty acid

Be able to draw!

17
Q

α-linolenic acid

A

Polyunsaturated fatty acid

18Cs 3 double bonds (18:3Δ9,12,15 (n-3))

linseed, soybean, and other seed oils

CH3-CH2-CH=CH-CH2-CH=CH-CH2-CH=CH-(CH2)7-COOH

or

CH3-(CH2-CH=CH)3-(CH2)7-COOH

essential fatty acid

18
Q

Fatty Acid Length

A

fatty acids with 14 or more carbon atoms are most important nutritionally and functionally

The following account for 90% of US diet:

palmitic acid (16:0)

stearic acid (18:0)

oleic acid (18:1)

linoleic acid (18:2)

In milk fat and coconut oil: butyric acid (4:0) and lauric acid (12:0)

19
Q

Melting Point

A

more saturation = higher melting point

longer chain - higher melting point

MP high for saturated fat bc double bond gives space between structure so heat can escape not as tightly packed

20
Q

Trans FA

A

partially hydrogenated fat (margerine; shortening)

problem: creates unnatural double bond

Foods: cookies, cakes, mostly baked goods

accumulate in the body (too straight)

21
Q

Essential Fatty Acids

A

linoleic (18:2 n-6)

α-linolenic acid (18:3 n-3) not common

prevents blood coagulation, lowers cholesterol, contains immunities, and hormone like regulations

essential bc humans lack enzymes called Δ12 and Δ15 desaturases, which incorporate double bonds at these positions (found only in plants)

humans can’t form double bonds beyond the Δ9 carbon in chain

FA elongation by enzymatic addition of 2 carbons @ carboxyl end of chain

EFA can make other FAs

Linoleic acid (18:2 n-6) -> γ-linolenic acid (18:3 n-6) -> Eicosatienoic acid (20:3 n-6) (intermediate) -> Arachidonic acid (20:4 n-6)

22
Q

n-3 Fatty Acids (omega 3s)

A

nutritional interest

hypolipidemic and antithrombotic effects

α-linolenic acid (18:3 n-3) vegetable oils

Docosahexaenoic acid DHA (22:6 n-3) fish oils

Eicosapentaenoic acid EPA (20:5 n-3) precursor of physiological important eicosanoids

fish oils particularly good source (lower lipid in blood and anti-blood clotting)

23
Q

Triacylglycerols (TAG)

A

Structure

3 fatty acids and a glycerol attached by ester bonds results in a lose of a water molecule

FA maybe all same (simple TG)

FA maybe different (mixed TG)

mostly stored body fat (highly concentrated energy)

95% of dietary fat

the 3 Carbons of glycerol each are disguishable by enzymes with specificity for one particular carbon

these 3 Carbons are number 1,2,3

C-2 has hydroxyl group to the left

TAG are fat or oil at room temp

SCFA or UFA liquid/oil

SFAs of longer chain length solid (high MP)

What makes fat solid? lack of double bonds and length (longer needs more heat)

Energy (free fatty acids during starvation)

FA released in free form from TAGs in adipocytes by hormone sensitive lipase (HSL)

FFA are transported by albumin to other tissues for oxidation

24
Q

Sterols and Steroids

A

class of lipids characterized by a four-ring core structure (steroid)

monohydroxy alcohols of steroidal structure

Cholesterol (most common)

sources: meat, egg yolk, and dairy products

exists in free form or hydroxyl group is esterified to FA

free form is absorbable

cholesteryl ester is not absorbed its too large

Chol is essential component of cell membranes (nerve tissue)

Chol serves as precursor for:

bile acids, steroid sex hormones (estrogen, progesterone), adrenocortical hormones, vit D of animal tissues

bile salts important bc emulsifies fat needs hydrophobic and hydophilic

each differ in arrangement of DBs, presenxe of carbonyl or hydroxyl groups, nature of side chain at C-17

all these structural modifications are mediated by enzymes

Not Essential - does have good functions

Sterols and phospholipids only make up 5% of dietary lipids when combined

25
Q

Phospholipids

A

contain phosphate

possess one or more FAs

2 Types:

  1. ) Glycerophosphatides - core structure is glycerol (3C)
  2. ) Sphingophosphatides - core structure is the amino alcohol sphingosine (palmitic acid + serine = 18C)

More polar than TAGs and Sterols (attract water molecules) on surface of chylomicrons

are polar - bc of this hydrophilic property are on the surface of blood-borne lipid particles such as chylomicrons which stablizes the particles in aqueous material

Serve as regulators of passage of water and fat-soluble materials across membrane

Important:

  1. memory structures
  2. emulsifiers
  3. myelin nerve protection
  4. enzymes 2nd messages and anchors
26
Q

Glycerophosphatides

A

FAs at C-1 (saturated) and C-2 (unsaturacted) of glycerol (nonpolar)

phosphoric acid at C-3 of glycerol (polar)

serve as structural support to the membrane and source of physiologically active compounds

phosphatidic acid from a number of derivatives:

  1. phosphatidylcholine** (lecithin)** - most common, is in egg yolk, good emulsifier melts in mouth makes smooth texture in chocolate
  2. phosphatidylethanolamine**
  3. phosphatidylserine**
  4. phosphatidylinositol** -

A. anchoring membrane PTNs when PTNs are covalently attached to lipids. (observed in cells treated with PI-specific phospholipase C caused hydrolyzing of ester bond connecting glycerol to phosphate

 B. also active in intracellular signaling they act as 2nd messengers in hormone stimulation (insulin) (cause release of Ca -\> Ca depend enzymes)
27
Q

Sphingolipids

A

not as common

found in cell membrane

emulsifer

myelin sheath - nervous tissue

  1. sphingomyelins
28
Q

Glycolipids

A

2 Types:

  1. cerebrosides
  2. gangliosides

have CHO component in structure

occur in medullary sheaths of nerves and in brain tissue

shingosine backbone and don’t contain phosphate

Macronutrients (4 decks)

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