Fat oral topics

Question 1

how are lipids soulbilized and digested

Answer 1

solubilized in bile salts, then degraded by pancreatic lipase in intestines

Question 2

what does pancreatic lipase generate

Answer 2

free FA and mix of mono/diacylglycerides - triacylglycerides are split at 1, 3 positions making 1,2-diacylglycerol and 2 acylglycerol

Question 3

phospholipid degr

Answer 3

at 2 position by pancreatic phospholipase

Question 4

absorption of fats

Answer 4

the products of pancreatic lipase are absorbed into intestinal mucosa cell and re-synthesized into triacyl glycerol

Question 5

how are triacylglycerols solubilized and transported

Answer 5

• 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)

Question 6

uptake of fat

Answer 6

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

Question 7

name the general steps of beta-ox of even FA

Answer 7

1. dehydration (FADH2 prod) 2. hydration 3. dehydration (NADHH prod) 4. thiolase cleavage

Question 8

how many cycles of beta ox of even (saturated) FA, and how many Ac~CoA are made

Answer 8

• *n/2-1**
  e. g. 16C/2 - 1 = 7 cycles

N/2= no. of AcCoA

e.g. 16C/2= 8 AcCoA

Question 9

energy balance of B-ox of (even) FA palmitoyl-CoA

Answer 9

8 AcCoA ⇒ 8*12 ATP

7 FADH2 ⇒ 7*2 ATP

7 NADH+H⁺ ⇒ 7*3 ATP

= 131ATP - 2 used in the synth, 129

Question 10

where does beta-ox of even FA not occur, and why

Answer 10

RBC: no mitochondrion

brain: to big to pass blood-brain barrier)

Question 11

unsaturated: cis vs. trans in B-ox

Answer 11

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

Question 12

difference in odd vs. even FA in beta oxidation

Answer 12

odd generates 7 fewer ATP’s per cycle:

• carboxylation of prop-CoA needs 1 ATP
• succinyl-CoA enters TCA instead of AcCoA -> -6ATP

Question 13

important co-factors in the reactions of prop-CoA→→→succinyl-CoA

Answer 13

biotin

vit. B12; DA-cobalamine

Question 14

ACP - acyl carrier protein: use in FA synthesis

Answer 14

“carries”/transports the acyl groups of the growing chain through even FA synthesis. it needs CoA. (synth of CoA needs vit B5/pantothenic acid)

Question 15

how do we go from one even FA cycle to another

Answer 15

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)

Question 16

how many cycles of even FA synth. to synthesize palmitic acid?

Answer 16

n/2-1

16C/2 - 1 = 7 cycles (7 malonyl-CoA)

Question 17

differences of odd carbon FA synthesis

Answer 17

the reaction of making malonyl CoA is the only difference, methyl malonyl-CoA is made instead

Question 18

making unsaturated FA

Answer 18

• cannot prod. double bond above delta9 →found in food, vitmins etc.
• oleic acid (C18, delta9) and stearic acid (C18) can be made

Question 19

how are omega 6 FA’s made

Answer 19

omega 6 linoleic acid makes arachidonic acid

Question 20

how are omega 3 FA made

Answer 20

omega-3 linoleninc acid ⇒ EPA ⇒ DHA

(EPA and DHA are found in fish)

Question 21

prostanoids

Answer 21

Inflammation and blood clotting

• *- good**: omega 3, decrease these
• *- bad**: omega 6, increase these

Question 22

whats a good prostanoid

Answer 22

CLA: conjugated linolenic acid - polyunsaturated

• anticancer
• no CH2 btw doble bonds: -CH=CH-CH=CH-
• ru: milk fat, plant origin

Question 23

where are trans FA found

Answer 23

• ru milk fat
• makes LDL (higher cholesterol and fats than VLDL)
• no flexibility: no bend

Question 24

importance of ketogenesis

Answer 24

• 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!))

Question 25

ketone body degradation

Answer 25

ketone bodies ⇒ AcCoA ⇒TCA⇒⇒⇒ glucose

Question 26

primary ketosis

Answer 26

• huge amount of energy needed
• diary ketosis: high yielding cows, GNG ⇒ use up OAC, accumilation of AcCoA

Question 27

secondary ketosis

Answer 27

• 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)