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Biochemistry I > SCT II - Lipid Metabolism I > Flashcards

SCT II - Lipid Metabolism I Flashcards

1
Q

Which two processes take place at the endoplasmic reticulum?

A

Elongation & Desaturation

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2
Q

Which process takes place in the mitochondrial matrix?

A

Breakdown of fatty acids (β-oxidation)

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3
Q

What is TAG?

A

TAG = Lipid

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4
Q

What is Acyl?

A

Acyl = Fatty acid

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5
Q

Which vitamins are lipid soluble?

A

Vit. A
Vit. D
Vit. E
Vit. K

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6
Q

What is the simplest fatty acid?

A

Palmitate (16 C)

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7
Q

What are essential fatty acids?

A

Fatty acids with double bounds beyond the 9th carbon

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8
Q

Where are steroids made?

A

Starts in cytosol, then into ER

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9
Q

What transporter transports Citrate?

A

Tricarboxylic acid transporter

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10
Q

How is Acetyl-CoA transported outside the mitochondrial matrix?

A
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11
Q

What is the rate limiting reaction of fatty acid synthesis?

A
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12
Q

What is the effect of insulin/glucagon on Acetyl-CoA Carboxylase?

A

Insulin
Induces dephosphorylation; activating the enzyme

Glucagon
Induces phosphorylation; inhibiting the enzyme

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13
Q

Name the inhibitors of Acetyl-CoA Carboxylase

A

Inhibition via Phosphorylation
1. cAMP (Activates Protein Kinase A, which phosphorylates)
2. AMP-Activated Kinases (AMP-Kinase)
3. Low ATP

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14
Q

Name the allosteric regulators of Acetyl-CoA Carboxylase

A

Allosteric Activators
1. Citrate (+ve Feedback)
2. Thyroid Hormone

Allosteric Inhibitors
- C16-C18 Fatty Acids

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15
Q

What are the properties of the enzyme Fatty Acid Synthase?

A
  1. It is a dimer
  2. It has 3 domains

Each domain contains an individual enzyme

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16
Q

What does the first domain of Fatty Acid Synthase contain?

A

3 Subunit Enzymes:
1. Malonyl-CoA Transferase
2. Condensing enzyme
3. Acetyl-CoA Transferase

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17
Q

What does the second domain of Fatty Acid Synthase contain?

A

3 Subunit Enzymes
1. Ketoacyl-CoA Reductase
2. β-Hydroxyacyl-CoA
3. Enoylacyl-CoA Reductase

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18
Q

What does the third domain of Fatty Acid Synthase contain?

A

1 Subunit Enzyme: Thioesterase

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19
Q

What carrier transports the acyl group from the first domain to the second?

A

ACP = Acyl Carrier Protein

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20
Q

What is the function of Thioesterase?

A

To hydrolyze the bond between Palmitate (16C) & ACP (Acyl-Carrier-Protein) so that it’s a free fatty acid

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21
Q

Draw the reactions that take place in the first domain of the Fatty Acid Synthase enzyme!

A
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22
Q

Draw the reactions that take place in the second domain of the Fatty Acid Synthase enzyme!

A
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23
Q

Draw the reactions that take place in the third domain of the Fatty Acid Synthase enzyme!

A
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24
Q

What are the three main steps of fatty acid synthesis?

A
  1. Reduction
  2. Dehydration
  3. Reduction
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25
What are the three main steps of fatty acid degredation?
1. Oxidation 2. Hydration 3. Oxidation
26
What is the use of NADPH in lipid metabolism?
NADPH serves as an electron donor in reduction (fatty acid synthesis)
27
Which substances does **Fatty Acid Synthase** depend on?
1. Pantothenate (Vit. B5) 2. Thiol of Phosphopantotheine 3. Cysteine residue of Condensing Enzyme
28
What is another name for the **Condensing Enzyme**?
β-Ketoacyl-Synthase
29
What is the main difference between the elongation in the mitochondria and the elongation in the endoplasmic reticulum?
**Endoplasmic Reticulum** Polyunsaturated fatty acids are elongated more **Mitochondria** Saturated fatty acids are elongated more
30
What is the equation of elongation in the endoplasmic reticulum?
31
What is the equation of elongation in the mitochondria?
32
Where does carbon desaturation take place?
Membrane of endoplasmic reticulum
33
What is desaturation?
Addition of a double bond
34
What carbon positions can humans desaturate?
4,5,6, and 9
35
Name the three desaturation enzymes
1. NADH-eyt b3 Reductase (Cytochrome b5 Reductase) 2. Cytochrome b5 3. Desaturase
36
When is a compound saturated?
When it has no double bonds
37
What is the ratio of NADH and double bonds in desaturation?
NADH:Double-bond (1:1)
38
Draw the pathway of the desaturation of a saturated fatty acid
39
Name the two important essential fatty acids
Omega-3: Linolenic Acid Omega-6: Linoleic Acid
40
Which protein surrounds a TAGs in an adipocyte?
Perilipin
41
What is the effect of Glucagon on TAG degradation?
42
How many fatty acids can bind to albumin?
3
43
What is another name for free fatty acids?
Non-esterified fatty acids
44
When is a fatty acid activated?
When it is bound to CoA
45
What is the enzyme responsible for the activation of fatty acids?
Fatty Acyl-CoA Synthetase
46
Is the activation of fatty acids an energetic or non-energetic process?
Uses ATP
47
Where does fatty acid degradation (β-oxidation) take place
Mitochondrial matrix
48
What number of carbon having fatty acid can pass by the inner mitochondrial membrane?
less than 12 via passive diffusion
49
What does CPT stand for?
Carnitine-Palmitoyl-Transferase
50
Which CPT is in IMM and OMM?
OMM = CPT I IMM = CPT II w/ Translocase
51
β-oxidation pathway
Fatty Acyl-CoA Dehydrogenase (FAD to FADH2)
52
What is the ratio of product after degradation of an even carbon fatty acid?
2:1 (16C:8AcetylCoA)
53
What is the ratio of product after degradation of an odd carbon fatty acid?
2:1 (17C:8AcetylCoA + 1Propionyl-CoA)
54
What is the final product of one β-oxidation cycle?
1 FADH2 1 NADH 1 Acetyl-CoA
55
Name all lipoproteins needed for fatty acid transport
**CM**: Chylomicron **VLDL**: Very low density lipoprotein **IDL**: Intermediate density lipoprotein **LDL**: Low density lipoprotein **HDL**: High density lipoprotein
56
In lipoproteins, what is the density (inversely) proportional to?
Density **prop.** to protein content Density **inv. prop.** to lipid content
57
What is the function of chylomicron (CM)?
Transport of TAG absorbed from intestines through blood
58
What is the function of LPL?
LPL is the middle man between tissue and Chylomicron, it takes what it needs and Chylomicron remains in blood till it's fully taken from multiple LPL
59
Where is the final destination of chylomicron?
Liver, deposits whatever fat is left via **LRP1 RECEPTOR**
60
Which apoprotein does LDLR bind?
ApoB-100
61
Which apoprotein does the LRP1 bind?
ApoE
62
What is the exogenous pathway?
Transport of absorbed lipids TO THE **LIVER**
63
What is the endogenous pathway?
Transport of synthesized lipids FROM THE **LIVER** to **TISSUE** then BACK TO THE **LIVER**
64
Can free fatty acids float in blood?
No, they bind to albumin
65

Biochemistry I (12 decks)

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