Other Lipds
Waxes: esters of fatty acids and long chain alcholos
Steroids:
insoluble in water*basic structure
Cholesterol
- precursor for sex hormonesCarotenoids
- carotene - yellow pigment of veggies (Vit. A precursor)
Monogastrics
Digestion:
goal = TG ® MG + 2 FA ® absorbedTG insoluble
® must become soluble1.
Course emulsion is formed - (Fat globule) in stomach - HCl2.
Bile acts to form droplet - duodenum3.
Lipase acts at the fat:water interface and cleaves FA #1 and #34.
Micelles - 2MG, FFA & bile salts are formed with polar (hydrophilic) on outside and non-polar (lipophilic) on inside of micelle5.
upon contact with microvilli in duodenum - MG & FFA absorbed6.
as absorbed, MD & FA are immediately resynthesized to TG and Phospholipids7.
TG droplets enveloped by lipoprotein - chylomicron - exits cell to lymph system (NOT BLOOD!!)8.
Glycerol is passively absorbed9.
short chain FA (more water soluble) are absorbed without chylomicron, and go to the blood. If #2 FA is short chain, goes to lymph!
Post-Absorption:
1.
2.
Converted to acetyl - CoA via b -oxidationacetyl CoA can be used for energy (NOT glucose), synthesis of fat, or formation of ketone body.
b
-Oxidation - O2 needed, so in the mitochondria.Break down of fat to acetyl-CoA
One fatty acid goes through several cycles.
1 Cycle
1.
2.
1 FADH23.
1 NADHTakes 2 ATP to activate (initial investment)
Examples:
Caproic Acid
C6:0 ® C6H12O22 cycles of
b -oxidation ®3 acetyl CoA X 12 = 36 ATP
2 turns of cycle X 5 = 10 ATP
= 46 ATP - 2 ATP (initial investment) yields 44 ATP
Glucose only yields 36 ATP.