Fat oral topics Flashcards
how are lipids soulbilized and digested
solubilized in bile salts, then degraded by pancreatic lipase in intestines
what does pancreatic lipase generate
free FA and mix of mono/diacylglycerides - triacylglycerides are split at 1, 3 positions making 1,2-diacylglycerol and 2 acylglycerol
phospholipid degr
at 2 position by pancreatic phospholipase
absorption of fats
the products of pancreatic lipase are absorbed into intestinal mucosa cell and re-synthesized into triacyl glycerol
how are triacylglycerols solubilized and transported
- packed into VLDL’s to be released into blood directly - packed into chylomicrons, to be transported in the lymph to reach the blood at thoracic inlet (storage or prod of energy by ox)
uptake of fat
VLDLs and chylomicrons are hydrolized to FFA and glycerol in caps of adipose tissue and skeletal muscle using lipoprotein lipase - FFA is absorbed by cell - glycerol into caps to liver to be converted to diOHacetonphosphate -> GNG/GL
name the general steps of beta-ox of even FA
- dehydration (FADH2 prod) 2. hydration 3. dehydration (NADHH prod) 4. thiolase cleavage
how many cycles of beta ox of even (saturated) FA, and how many Ac~CoA are made
- *n/2-1**
e. g. 16C/2 - 1 = 7 cycles
N/2= no. of AcCoA
e.g. 16C/2= 8 AcCoA
energy balance of B-ox of (even) FA palmitoyl-CoA
8 AcCoA ⇒ 8*12 ATP
7 FADH2 ⇒ 7*2 ATP
7 NADH+H⁺ ⇒ 7*3 ATP
= 131ATP - 2 used in the synth, 129
where does beta-ox of even FA not occur, and why
RBC: no mitochondrion
brain: to big to pass blood-brain barrier)
unsaturated: cis vs. trans in B-ox
even: trans, uneven: cis (creates bend)
- uneven beta ox needs 2 extra ATP to convert cis to trans, so that the A,B-enoyl-CoA hydratase of B-ox to function - needs A,B configuration
difference in odd vs. even FA in beta oxidation
odd generates 7 fewer ATP’s per cycle:
- carboxylation of prop-CoA needs 1 ATP
- succinyl-CoA enters TCA instead of AcCoA -> -6ATP
important co-factors in the reactions of prop-CoA→→→succinyl-CoA
biotin
vit. B12; DA-cobalamine
ACP - acyl carrier protein: use in FA synthesis
“carries”/transports the acyl groups of the growing chain through even FA synthesis. it needs CoA. (synth of CoA needs vit B5/pantothenic acid)
how do we go from one even FA cycle to another
malonyl-s-ACP binds to endprod (1st: butyryl-s-ACP) by condensation (s-s), forming a 6 carbon compound (leangtened by 2 carbons each cycle)
(Acetyl transacetylase enzyme is needed)
how many cycles of even FA synth. to synthesize palmitic acid?
n/2-1
16C/2 - 1 = 7 cycles (7 malonyl-CoA)
differences of odd carbon FA synthesis
the reaction of making malonyl CoA is the only difference, methyl malonyl-CoA is made instead
making unsaturated FA
- cannot prod. double bond above delta9 →found in food, vitmins etc.
- oleic acid (C18, delta9) and stearic acid (C18) can be made
how are omega 6 FA’s made
omega 6 linoleic acid makes arachidonic acid
how are omega 3 FA made
omega-3 linoleninc acid ⇒ EPA ⇒ DHA
(EPA and DHA are found in fish)
prostanoids
Inflammation and blood clotting
- *- good**: omega 3, decrease these
- *- bad**: omega 6, increase these
whats a good prostanoid
CLA: conjugated linolenic acid - polyunsaturated
- anticancer
- no CH2 btw doble bonds: -CH=CH-CH=CH-
- ru: milk fat, plant origin
where are trans FA found
- ru milk fat
- makes LDL (higher cholesterol and fats than VLDL)
- no flexibility: no bend
importance of ketogenesis
- creates additional energy store using fat
- used in time of starvation, diabetes, GI diseases
- e.g. in early lactation of ru: incr. GNG
- fuel for brain, heart, muscles
- incr. ketogenesis ⇒ acidosis (ketonaemia, ketonuria(energy loss!))
ketone body degradation
ketone bodies ⇒ AcCoA ⇒TCA⇒⇒⇒ glucose
primary ketosis
- huge amount of energy needed
- diary ketosis: high yielding cows, GNG ⇒ use up OAC, accumilation of AcCoA
secondary ketosis
- not enough energy is taken up
- starvation, GI diseases, diabetes (ketoacidosis, switch to FA burning since lack of insulin doesnt allow glucose to enter cell)
