Lipids Flashcards
what does lipid contain?
- 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
fatty acids
- contain an even # of carbon atoms
- unbranched lines
- have carboxyl group on one end (-COOH) & methyl group (CH3) on the other end
fatty acid chain lengths
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
saturate fats
- NO DOUBLE BONDS
- solid at room temperature:
- Butter, shortening, lard, coconut oil, palm oil, and
fully hydrogenated vegetable oils - Poultry skin, whole milk
- Butter, shortening, lard, coconut oil, palm oil, and
mono-unsaturated fats
- 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)
poly-unsaturated fats
- 2 or MORE double bonds
- include:
- omega 3 FAs: linolenic acid
- omega 6 FAs: linoleic acid
- rich sources: vegetable oils
cis vs trans chain
cis: has a bent in the chain
trans: NO bent in the chain -> straight
trans-fatty acids
- natural or manufactured
- 1+ double bond
- unsaturated FA that acts like saturated FA
what acid can be synthesized by linoleic acid?
Arachidonic acid = not essential
EXCEPT cats
what omega position can animals synthesize FAs?
- Omega 9
NOT omega 3 & 6 = must be derived from the diet
- cold water fish accumulate HIGH omega 3 FAs
what acid(s) can be synthesized by linolenic acid?
- eicosapentaenoic acid (EPA)
- docosahexaenoic acid (DHA)
what are the physical traits for FAs?
- 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)
what type of FA does great with oxygen present?
- unsaturated FAs:
- auto-oxidation, peroxidation, rancidity
- free radicals formed
- antioxidants prevent oxidation
hydrogenation / saturation
- making unsaturated FAs -> saturated FAs
- convert by rumen microbes
- create trans-FAs
what are the functional properties of hydrogenation/saturation?
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
what are the challenges & goals in monogastrics?
goals:
- make lipids soluble in water
- breakdown of triglycerides & phospholipids
- lipids are hydrophobic
- triglycerides are too large to be absorbed
bile
- 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
digestion of lipid path…
mouth: minimal digestion ->
stomach: minimal digestion ->
small intestine: major site for digestion ->
large intestine: <5% of fat
micelle formation
- 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
lipid absorption
- 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
can cholesterol be digested?
NO, cholesterol cannot be digest, but is absorbed with other lipid components
lipid transport
- Triglycerides and cholesterol require
carriers in the blood or lymph- Lipoproteins are those carriers!
what are the 4 lipoproteins?
- Chylomicron - mostly TG
Carries lipid from the small intestine to
lymph/blood/cells/liver - Very low-density lipoprotein (VLDL)- mostly TG
Carries lipid from the liver to blood/cells - Low density lipoprotein (LDL)- mostly cholesterol
Made from VLDL as TG are removed - High density lipoprotein (HDL) - mostly protein
Carries lipid to liver for removal
lipolysis
Mobilization of body triglycerides for use
as energy
triglyceride catabolism
- Glycerol is used for energy or
gluconeogenesis - FFA is oxidized to CO2 and H2O
taken in place in the mitochondria
where are steroid hormones derived from?
cholesterol
Lipid Peroxidation
- Auto-oxidation of lipids causing rancidity
- Dangerous to health – linked to
cancers, heart disease, inflammation
and aging
antioxidant nutrients
- 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
what are the 6 antioxidant nutrients
- vit. E
- vit. C
- carotenoids
- selenium
- carnitine
- polyphenols
