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Bio 540 - Biochem > Exam 4 - Lipid Metabolism > Flashcards

Exam 4 - Lipid Metabolism Flashcards

1
Q

What are the two most important tissues with respect to TAG production?

A

Liver and adipose

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2
Q

TAG is stored as lipid droplets in the []

A

cytoplasm

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3
Q

What “form” is TAG transported through the blood as?

A

Plasma-lipoprotein

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4
Q

Chylomicrons are a type of what….?

A

Plasma-lipoprotein

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5
Q

In a fasted states FA could be used for 2 things:

  1. Burned for energy to make []
  2. Used to make [] bodies
A
  1. glucose
  2. Ketone bodies
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6
Q

Acyl-CoA Synthetase does?

A

Activates fatty acids to acyl-CoA using ATP and CoASH

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7
Q

What primary intermediate do we need to get to in order to take Glyceraldehyde 3-Phosphate to TAG?

What 2 reactions take place to reach this intermediate?

A
  1. Lysophosphatidic Acid
  2. Reduction and Acylation
    1. Depends on the minor or major pathway for which one is first
    2. If Major pathway - reduction, followed by acylation
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8
Q

What is the path of “main” molecules from Glucose –> TAG?

A
  • Glucose –> Glyceraldehyde 3-P
  • Glyceraldehyde 3-P —> Glyceral 3-P
  • Glycerol 3-P —> Lysophosphatidic acid
  • Lysophosphatidic Acid —> Phosphatidic Acid
  • Phosphatidic Acid —> DAG
    • removal of a Pi
  • DAG —> TAG
    • Addition of Acyl group
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9
Q

Glycerol 3-Phosphate acyl transferase does what?

A
  • Adds a Carbonyl/Acyl group to a glycerol 3-P molecule making the lysophosphatidic acid
    • Lyso means it only has 1 acyl group
    • The other group is an OH and the phosphate
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10
Q

What enzyme adds a second acyl group onto lysophosphatidic acids?

What would the product be?

A

Lysophosphatidic acid acyl transferase

Phosphatidic Acid

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11
Q

What acyltransferase acylates DHAP in TAG synth?

A

DHAP acyltransferase

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12
Q

What enzyme oxdizes acyldihydroxyacetone phosphate?

A
  • Psych
  • This enzyme reduces it - produces an NADP+
  • Acyldihydroxyacetone Phosphate reductase
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13
Q

What enzyme catalyzes the reaction of PA to DAG?

What “mechanism” does it use?

A

Phosphatidate phosphatase (or phosphatidic)

Hydrolyzes the phosphate

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14
Q

What enzyme catalyzes DAG —> TAG?

A

DAGAT

Diacylglycerate acyltransferase

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15
Q

What are all the acyltransferases in the Major and Minor Pathways of TAG synthesis?

A
  • Major
    • Glycerol 3-P acyltransferase
  • Minor
    • DHAP acyltransferase
  • Major and Minor - both meet at Lysophosphatidic Acid
    • Lysophosphatidic Acyltransferase
    • Diacylglycerate acyltransferase
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16
Q

What are the non acyltransferases in TAG synth?

A
  • Major
    • DHAP –> Glycerol 3-P…some sort of reductase
  • Minor
    • AcylDHAP Reductase
  • Both
    • Phosphatidic Phosphatase
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17
Q

During fasting - does the body overcompensate by producing fatty acids form fat cells?

During fasting - glycerol production is [] via glycolytic intermediates, but requires [] …?

A

Yes

Not, Glyceroneogenesis

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18
Q

What are the 3 ways to utilize fatty acids for energy?

A
  1. Hydrolysis of Acyl groups from TAG
  2. Lipid Transport
  3. Deriving energy from fatty acids (B-Ox for example)
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19
Q
  1. Acyl groups hydrolysis from glycerol lipids is catalyzed by []
  2. [] are specfic for the lipid species and acyl position
  3. Adipose cells utilizes [] responsive lipases
  4. Any remaining glycerol is transported to the [] to be converted to []
A
  1. lipases
  2. Lipases
  3. hormone
  4. liver, DHAP
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20
Q

What are the 3 types of lipids that are transported…and how is each transported?

A
  1. TAG
    1. PLP - plasma lipoproteins
  2. Fatty Acids
    1. Sereum Albumin (non covalent interactions)
  3. Ketone Bodies
    1. aqueous soluble…no transporter necessary
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21
Q

What are the 3 lipid transport pathways?

A
  1. Dietary Pathway
  2. Liver Pathway
  3. Fat Cell Pathway
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22
Q
  1. Bulk of blood lipid is []
  2. [] bound fatty acids have the highest turnover rate
A
  1. TAG
  2. Albumin
23
Q

What are the 2 types of plama lipoproteins we covered?

A
  1. Chylomicrons
  2. VLDL - very low density lipoproteins
24
Q
  • Chylomicrons function in the [] in abosprtion and [] of dietary TAG, [] , and fat -soluble vitamins
  • VLDLS
    • synthesized in the []
    • Transports [] and [] to adipose tissue
      *
A
  1. intestine, transport, cholesterol
  2. Liver, TAG and fatty acids
25
1. What does Serum Albumin do? 2. What are the 2 ketone bodies?
1. hydrolysis of fatty acids from TAG in the blood 2. Acetoacetate and B-hydoxybutyrate
26
What are the 2 Ketone Bodies, and how is each made?
1. Acetoacetic Acid 1. Condense 2 acetic acids 2. B-Hydoxybutyric Acid 1. Reductino of acetoacetic Acid.....
27
B-oxidation is [] -iterative process for [], []-numbered, [] chain fatty acids....
1. 4 step 2. saturated 3. even numbered 4. straight chain
28
Why are fatty acids linked to ACP during B-oxidation?
* Psych! * They are linked to **CoA** during B-oxidation!!
29
What are the 4 "generic" steps of B-oxidation?
1. Oxidation 2. Hydration 3. Oxidation 4. Lysis
30
Fatty Acids must be activated to the CoA ester by [] ??
Acyl CoA synthetase
31
What molecule acts as a carrier of FA from the cytosl into the mitochondria? What is the name of this system? How many carbon-long chains does it normally transport?
* Carnitine * Carnitine Palmital Transport * 12-18 Carbons
32
Where is carnitine located as a transport molecule? What is the negative effector of the carnitine transport system?
* In between outer and inner mitochondrial membrane * Malonyl CoA * This is used to make FA - so of course it would be a negative effector of shit trying to break down FA like B-Ox
33
What are the 4 enzymes used for normal B-ox?
Acyl-CoA dehydrogenase Enoyl-CoA hydratase Hydroxyacyl-CoA dehydrogenase Ketoacyl-CoA thiolase
34
How many ATP does Acyl CoA Synthetase require to active the acyl fatty acids?
2 ATP
35
What does Acyl-CoA dehydrogenase do? What are this enzymes products?
* removes two electrons and forms and enoyl-CoA with trans double bond between the Alphat and Beta carbon * Products: * trans-delta2-Enoyl CoA * FADH2
36
What does Enoyl-CoA hydratase do? What are this enzymes products?
* adds a water molecule across the trans double bond (lyase reaction) of trans-delta2-Enoyl-CoA... to generate a hydroxylacyl-CoA * Products: * 3-L-Hydroxyacyl-CoA
37
What does Hydroxyacyl-CoA dehydrogenase do? What are this enzymes products?
* removes two electrons, reducing the hydroxyl group to a keto group * Produts: * B-Ketoacyl-CoA * NADH
38
What does Ketoacyl-CoA thiolase do? What are this enzymes products?
* catalyzes the thioester cleavage and generates an acetyl-CoA and a fatty acid that is shorter by two carbons. * Products: * Acetyl-CoA * 2 carbon shorter FA
39
Roughly, how many ATP does Acetyl-CoA get you through Krebs....
10 ATP
40
* Citrate and isocitrate act as [] regulators of ACCase through [] activation * C16 -C18 acyl CoAs act as [] regulators of ACCase through [] inhibition
* Positive, allosteric * Negative allosteric
41
How does insulin and glucagon effect ACCase?
* Glucagon - inhibits it via PKA phosphorylation of ACC * Insulin - activation by dephosphorylation of ACC
42
How many ATP are used to make palmitate and acetyl CoA?
42 ATP
43
What are the differences in the steroechemical configurations of the B-hydroxy intermediats of Lipid Biosynth and B-Ox?
* Biosynthesis * D * B-Ox * L
44
Why does our normal Enoyl hydratase in B-Oxidation not work on unsaturated FA?
Becuase Enoyl hydratatse requires a trans double bond between the C2 and C3...however, unsaturated Fats have a cis double bond here.
45
* Enoyl-CoA isomerase* does what?? * 2,4-dienoyl-CoA reductase* does what? * Enoyl-CoA isomerase* does what?
1. converst a cis C3 double bond to a trans C2 double bond 2. uses NADPH to produce trans C3 enoyl-CoA 3. Converts the trans C3 enoyl-CoA to a trans C2 enoyl-CoA
46
a-oxidation 1. [] carbon elimination 2. Requires a-carbon [] 3. Used to removes [] from branched chain FA 4. Occurs in the [] , [] , and predominately the []
1. 1 carbon 2. hydroxylation 3. branched 4. mitochondria, ER, peroxisome
47
What type of oxidation could yield a dicarboxylate?
w-oxidation
48
Where is the primary site of Ketone Body Synth?
Liver
49
What enzyme forms acetoacetyl-CoA by condensation reaction between two acetyl-CoA molecule in the mitochondria?
B-ketothiolase
50
What is HMG-CoA Synthase's function?
forms HMG-CoA by condensation reaction between acetoacetyl-CoA and acetyl-CoA
51
What is HMG-CoA Lyase's function?
cleaves HMG CoA into acetoacetate and Acetyl-CoA
52
What enzyme uses NADH to reduce acetoacetate to B-hydroxybutyrate?
B-hydroxybutyrate dehydrogenase
53
How many CoA's are invested into the making of Ketone bodies...but how many are "actually" used?
* 3 total are invest * 1 is remade though...so only 2 are used.
54
What enzyme activates acetoacetate in muscle/brain cells in order to utilizes ketone bodies for energy?
3-oxoacid-CoA transferase OR **Thioferase** - This adds a CoA to acetoacetate!

Bio 540 - Biochem (14 decks)

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