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Med 1: GI > Goal 8: TAG Synthesis > Flashcards

Goal 8: TAG Synthesis Flashcards

1
Q

Only what can you get triacyglycerol from?

A
  • Glucose!

- not from insulin

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2
Q

In TAG synthesis, what pathway gives NADPH, which is needed to turn acetyl CoA to Fatty acids?

A

Pentode P Pathway (HMP shunt)

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3
Q

What are the main sites of TAG synthesis?

A
  • MAINLY Liver and lactating mammary glands

- partially in adipose tissue

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4
Q

What is the precursor required for TAG synthesis? What is required for the precursor to even be created?

A
  • precursor: acetyl CoA needed for TAG synthesis

- glucose needed to make acetyl CoA

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5
Q

Where is Acetyl CoA produced?

A

Mitochondria

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6
Q

Where does fatty acid biosynthesis happen?

A
  • In cytosol

- DONT confuse with elongation of fatty acids which happen in smooth ER

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7
Q

Acetyl CoA can’t go from mitchochondria to cytosol without what?

A
  • Converting into citrate to go through citrate shuttle to mitochondria
  • once it gets to cytosol, citrate is turned back to Acetyl CoA
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8
Q

What enzyme turns NADP to NADPH? Where does it happen?

A
  • malic enzyme

- cytosol

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9
Q

What is the first step of fatty acid biosynthesis? What regulatory enzyme makes this happen? What coenzymes are required to make it happen?

A
  • Acetyl CoA turned into Malonyl CoA
  • enzyme used: Acetyl CoA Carboxylase
  • required coenzymes: ABC- ATP, Biotin, CO2
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10
Q

What are the 2 regulatory enzymes for de novo synthesis of fatty acids?

A
  • Acetyl CoA Carboxylase MAJOR ONE

- Fatty acid synthase

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11
Q

What is the allosteric activator of Acetyl CoA Carboxylase? Allosteric inhibitor?

A
  • activator: citrate

- inhibitor: long chain fatty acyl CoA like palmitoyl CoA

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12
Q

What enzyme in glycolysis does citrate allosterically inhibit?

A

PFK1

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13
Q

What is the difference between Acetyl CoA Carboxylase’s active form and inactive form?

A
  • active: tightly connected, in a chain

- inactive: disconnected, scattered

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14
Q

What 4 enzymes are active in dephosphorylated state?

A
  • Acetyl CoA Carboxylase
  • glycogen synthase
  • pyruvate kinase
  • PDH complex
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15
Q

How is Acetyl CoA Carboxylase in the dephosphorylated state? How about the phosphorylated state?

A
  • dephos: active

- phospho: inactive

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16
Q

What is insulin’s effect on Acetyl CoA Carboxylase (ACC)? What inhibits it ACC?

A
  • activates it by promoting dephosphorylation

- epinephrine and glucagon promote phosphorylation and inactivates ACC

17
Q

What type of diet stimulates ACC and fatty acid synthase? What diet decreases it? What protein mediates this process through insulin?

A
  • stimulates: high carbohydrate
  • inhibits: low carbohydrate
  • sterol regulatory element binding protein (SREBP-1)
18
Q

De novo synthesis of fatty acids is terminated by the formation of what?

A

Palmitic acid (16C)

19
Q

What process is done to make a higher chain length of fatty acids? Where does it happen?

A
  • elongation of fatty acids

- smooth ER

20
Q

What is desaturation? Where does it happen? What is stearic acid turned into when desaturated? Palmitic acid? What enzyme and coenzymes are required for this to happen?

A
  • double bonds added to fatty acids; saturated fatty acids give rise to unsaturated fatty acids
  • smooth ER
  • oleic acid
  • palmitoleic acid
  • desaturases; cytochrome b5, NADH, 02
21
Q

What two essential polyunsaturated fatty acids can the body not synthesize? Why? How can we do it then?

A
  • linoleic acid and linolenic acid
  • can’t desaturate it because there’s an existing double bond already
  • need to change linoleic acid to arcachidonic acid by desaturation and elongation
22
Q

What components are required for TAG synthesis?

A
  • Acyl CoA (activated free fatty acid)

- glycerol 3-phosphate

23
Q

What are the two sources of fatty acid used in TAG synthesis?

A
  • Chylomicron- from diet

- VLDL- from liver

24
Q

What enzyme is used to activate fatty acid?

A

Acyl CoA synthase(thiokinase)

25
Q

What are the two sources of Gylcerol 3-Phosphate?

A
  • Glycolysis: glucose-> DHAP->glycerol 3P

- from free glycerol in liver( NOT ADIPOSE TISSUE): glycerol to gylcerol 3p with glycerol kinase

26
Q

What hormone stimulates TAG synthesis under well fed conditions? At what sites?

A
  • Insulin

- liver and adipose tissues

27
Q

What mediates the insulin transportation of glucose into adipose cells?

A

GluT 4

28
Q

What happens to the TAGs after they’re synthesized in the liver? Are the TAGs meant to store and save for later?

A
  • transported out of liver through VLDL

- TAGs aren’t meant to store in the liver, this can lead to Fatty Liver

29
Q

What happens to TAGs after synthesized in adipose tissue?

A

-it’s stored in adipose and saved until it needs to be degradated

Med 1: GI (15 decks)

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