Lipid Metabolism 1 Flashcards Preview

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Flashcards in Lipid Metabolism 1 Deck (26):
1

What is a fatty acid derivative?

Contains fatty acids

2

What is an eicosanoid?

Derived from 20 carbon arachidonic acid

3

What is an isoprene derivative and what are some examples?

Made of multiple isoprene units. Lipid soluble vitamins, ubiquinone, cholesterol, steroids.

4

Where does FA synthesis occur mainly and name a few secondary?

Liver. Also adipose tissue (Not important brain, kidneys)

5

What two places in the cell does FA synthesis occur?

Cytosol and mitochondria

6

What is the end product of FA synthesis? The precursor?

16 Carbon FA Palmitic acid Acetyl CoA

7

What are the three main steps in FA synthesis?

1. Cytosolic entry of Acetyl CoA 2. Generation of Malonyl CoA 3. Fatty acid chain formationly

8

What converts Acetyl-CoA +OAA to Citrate?

Citrate Synthase

9

What converts Citrate to Acetyl-CoA and OAA?

Citrate Lyase

10

What induces gene expression of Citrate Lyase? What counter acts it? Is the enzyme stimulated or unstimulated by phosphorylation?

Activators: Glucose, Insulin Inhibitors: PUFA, Leptin Stimulated by phosphorylation

11

What does Acetyl CoA get converted to in FA synthesis? What is the enzyme responsible? What is the enzymes cofactor? Is this the rate limiting step? What are the two other reactants used in this reaction?

Malonate CoA Acetyl CoA Carboxylase Biotin Rate limiting step of FA Synthesis Co2 and ATP

12

Is Acetyl CoA Carboxylase activated or deactivated by Phosphorylation? What activates Acetyl CoA Carboxylase? (2) Which of these are allosteric? What inhibits Acetyl CoA Carboxylase? (5) Which two of these are allosteric? Does a high carb/low fat diet up or down regulate gene expression?

Activators: Citrate (Allosteric), Insulin (De-Phosphorylates) Inhibitors: Palmitate/PUFA (Allosterics) Glucagon/Epinephrine/High AMP (Phosphorylation) Deactivated by phosphorylation Up regulates

13

What is PUFA?

Poly unsaturated fatty acids

14

What does Malonyl CoA inhibit? What is the significance of this enzyme? What is the significance of this inhibition?

Carnitine Acyltransferase This is the rate limiting enzyme in FA degradation This prevents FAs from being synthesized and degraded simultaneously

15

On what complex does fatty acid synthesis occur? What is the structure of the enzyme and how is it composed?

Fatty Acid Synthase Complex (FAS) 2 Identical dimers in head to tail configuration, Each has 7 Enzyme activities and an Acyl Carrier Protein (ACP) It also has a flexible arm

16

What does malonyl CoA get converted to?

Palmitate (16C)

17

What are the carbon stoichiometry units in the Palmitate Synthesis reaction?

7 Malonyl CoA + 1 Acetyl CoA = Palmitate (16C) + 8 CoA

18

What is the reaction order by the Fatty Acid Synthase complex? How many cycles? What are the starting molecules? What carbon molecule is added every time? What is the final product? What are the sources of NADPH?

Condensation, Reduction, Dehydration, Reduction. 7 cycles. Acetyl CoA, Malonyl Group Malonyl Group Palmitate 1 from the Malic Enzyme, 11 from PPP

19

For the Fatty Acid Synthase Complex What has an allosteric effect of this? What things increase synthesis at gene level? (3) What things suppress synthesis? (3)

Phosphorylated Sugars increase its activity Insulin, glucocorticoids, High carb/Low fat diets High fat diets, starvation, High PUFA

20

What kind of macromolecule is leptin? It is secreted in direct proportion to ___ mass. What receptor does it act through and where is this expressed? How does it regulate body weight? (2)

16kDA protein Fat Leptin Receptor in Hypothalamus Inhibits food intake, stimulates energy expenditure

21

Where does FA elongation occur? (2) What are the carbon donors in each place? How many carbons is it lengthened at a time? What is used for reducing power?

Smooth Endo. Ret. (SER), Mitochondria Malonyl CoA, Acetyl CoA 2 NADPH

22

In what form are Fatty Acids incorporated into lipids?

TriacylGlycerols

23

What catalyzes FA Desaturation? What induces their gene expression? What suppresses their gene expression? How does Cholesterol affect expression? What is used to reduce? Beyond what two carbons in a FA can a double bond not be synthesized in humans? What are the precursors in FA desaturation?

  • Acyl CoA Desaturases
  • Insulin
  • PUFAs
  • induces expression of Delta9 Desaturase, suppresses all others
  • NADPH or NADH
  • Carbons 9 and 10
  • Essential Fatty Acids

24

What are the precursors of omega 3 and 6 FAs called? What are two examples Why are they called this? What is Linoleic acid used to make? What is Linolenic used to make?

Essential Fatty Acids? Linoleic acid (omega 6) Linolenic acid (omega 3) Cannot be synthesized by humans Arachidonic acid (omega 6), a eicosanoid precursor Eicosapentanoic acid (omega 3) and docosahexanoic acid (DHA)

25

What do the phrases omega 3 and 6 imply?

Double bond at the 3rd carbon from the methyl end Double bond at the 6th carbon from the methyl end

26

In the B-Oxidation of Palmitic Acid How many FADH2 created and how much ATP is this? How many NADH created and how much ATP is this? How many ATP created and how much ATP is this? What is the Total ATP Released? What is the net ATP released?

7 x 1.5 = 10.5

7 x 2.5 = 17.5

8 x 10 = 80

Total = 108

106 (2 used to activate palmitate)