Lipids Flashcards

1
Q

what does lipid contain?

A
  • C, H, O
  • soluble in non-polar organic solvents
  • Includes: mostly triglycerides
    • fats: solid at room temp.
    • oils: liquid at room temp.
  • 3 fatty acids + glycerol
  • other lipids:
    • phospholipids
    • free fatty acids
    • cholesterol
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2
Q

fatty acids

A
  • contain an even # of carbon atoms
  • unbranched lines
  • have carboxyl group on one end (-COOH) & methyl group (CH3) on the other end
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3
Q

fatty acid chain lengths

A

short: 2-6C
medium: 8-12C
long: 14-24C

  • as the chain increases = the melting point increases
  • fatty acids synthesized by plants & animals =
    • mostly long chain
    • 16-18C fatty acids
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4
Q

saturate fats

A
  • NO DOUBLE BONDS
  • solid at room temperature:
    • Butter, shortening, lard, coconut oil, palm oil, and
      fully hydrogenated vegetable oils
    • Poultry skin, whole milk
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5
Q

mono-unsaturated fats

A
  • ONLY one double bond
  • liquid at room temperature:
    - Olive oil, canola oil, peanut oil
    - Other sources: avocado, almonds,
    cashews, pecans and sesame seeds
    (tahini paste)
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6
Q

poly-unsaturated fats

A
  • 2 or MORE double bonds
  • include:
    • omega 3 FAs: linolenic acid
    • omega 6 FAs: linoleic acid
  • rich sources: vegetable oils
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7
Q

cis vs trans chain

A

cis: has a bent in the chain
trans: NO bent in the chain -> straight

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8
Q

trans-fatty acids

A
  • natural or manufactured
  • 1+ double bond
  • unsaturated FA that acts like saturated FA
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9
Q

what acid can be synthesized by linoleic acid?

A

Arachidonic acid = not essential
EXCEPT cats

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10
Q

what omega position can animals synthesize FAs?

A
  • Omega 9

NOT omega 3 & 6 = must be derived from the diet

  • cold water fish accumulate HIGH omega 3 FAs
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11
Q

what acid(s) can be synthesized by linolenic acid?

A
  • eicosapentaenoic acid (EPA)
  • docosahexaenoic acid (DHA)
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12
Q

what are the physical traits for FAs?

A
  • Form membranes, micelles, liposomes
    • Orient at water: oil interface
    • Contain hydrophobic and hydrophilic groups
    • Lipid bilayer for membranes
    • micelles formed during digestion

FAs forms “soaps” with cations:
- Na & K soaps = water soluble
- Ca & Mg soaps = NOT water soluble (poorly digested)

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13
Q

what type of FA does great with oxygen present?

A
  • unsaturated FAs:
    • auto-oxidation, peroxidation, rancidity
    • free radicals formed
    • antioxidants prevent oxidation
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14
Q

hydrogenation / saturation

A
  • making unsaturated FAs -> saturated FAs
    • convert by rumen microbes
  • create trans-FAs
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15
Q

what are the functional properties of hydrogenation/saturation?

A

excess energy from carbohydrates, proteins, and lipids are stored as triglycerides in adipose tissue

  • provide insulation to the body from cold
  • mechanical insulation
  • electrical insulation
  • supply essential FAs (EFAs)
  • formation of cell membranes
  • help transport fat-soluble vitamins
  • help control appetite
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16
Q

what are the challenges & goals in monogastrics?

A

goals:
- make lipids soluble in water
- breakdown of triglycerides & phospholipids

  • lipids are hydrophobic
  • triglycerides are too large to be absorbed
17
Q

bile

A
  • produced in the liver -> stored in the gall bladder
    EXCEPT FOR HORSES
  • responsible for fat emulsification
  • alkaline solution composed of:
    • bile salts
    • cholesterol
    • lecithin
    • bilirubin
18
Q

digestion of lipid path…

A

mouth: minimal digestion ->
stomach: minimal digestion ->
small intestine: major site for digestion ->
large intestine: <5% of fat

19
Q

micelle formation

A
  • a complex of lipids soluble in water
  • contains:
    • bile salts
    • cholesterol
    • phospholipids

combines: 2-monoglycerides, free
fatty acids and fat-soluble vitamins to
form mixed micelles

20
Q

lipid absorption

A
  • Mixed micelles move to intestinal
    mucosal cells (enterocytes) and release
    contents near cell
  • bile salts are re-absorbed further
    down the GIT (in the ileum), transported
    to the liver, and finally recycled and
    secreted back into the digestive tract
21
Q

can cholesterol be digested?

A

NO, cholesterol cannot be digest, but is absorbed with other lipid components

22
Q

lipid transport

A
  • Triglycerides and cholesterol require
    carriers in the blood or lymph
    • Lipoproteins are those carriers!
23
Q

what are the 4 lipoproteins?

A
  1. Chylomicron - mostly TG
    Carries lipid from the small intestine to
    lymph/blood/cells/liver
  2. Very low-density lipoprotein (VLDL)- mostly TG
    Carries lipid from the liver to blood/cells
  3. Low density lipoprotein (LDL)- mostly cholesterol
    Made from VLDL as TG are removed
  4. High density lipoprotein (HDL) - mostly protein
    Carries lipid to liver for removal
24
Q

lipolysis

A

Mobilization of body triglycerides for use
as energy

25
Q

triglyceride catabolism

A
  • Glycerol is used for energy or
    gluconeogenesis
  • FFA is oxidized to CO2 and H2O
    taken in place in the mitochondria
26
Q

where are steroid hormones derived from?

A

cholesterol

27
Q

Lipid Peroxidation

A
  • Auto-oxidation of lipids causing rancidity
  • Dangerous to health – linked to
    cancers, heart disease, inflammation
    and aging
28
Q

antioxidant nutrients

A
  • fight harmful particles in
    the body is known as free radicals = damage cells & tamper with DNA
  • can neutralize free radicals
    and may reduce or help prevent some
    of the damage they cause
29
Q

what are the 6 antioxidant nutrients

A
  1. vit. E
  2. vit. C
  3. carotenoids
  4. selenium
  5. carnitine
  6. polyphenols