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Biochemistry > Biochem Exam 3: Lipid Metabolism > Flashcards

Biochem Exam 3: Lipid Metabolism Flashcards

1
Q

What is a major source of carbon for fatty acid synthesis?

A

Dietary carbohydrates

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2
Q

Where does fatty acid synthesis primarily occur?

A

Liver;

It can also occur in adipose tissue, brain, kidneys, & lactating mammary glands

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3
Q

What is a precursor molecule for fatty acid synthesis?

A

Acetyl CoA

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4
Q

What is phase 1 of FA synthesis?

A

Cytosolic entry of acetyl CoA (made in mitochondria but needed in cytoplasm)

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5
Q

What is phase II of FA synthesis?

A

Generation of Malonyl CoA (acetyl CoA is carboxylase to malonyl CoA)

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6
Q

What is phase III of FA synthesis?

A

Fatty acid chain formation. ( the enzyme fatty acid synthase catalyzes 7 reactions that incorporate acetyl CoA and malonyl CoA into plamitate (C16))

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7
Q

What is the most important phase of FA synthase?

A

Phase II; Rate limiting step

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8
Q

How does acetyl CoA leave the mitochondria?

A

As citrate using the citrate shuttle

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9
Q

What enzyme breaks citrate down into oxaloacetate and acetyl CoA?

A

ATP citrate lyase

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10
Q

What is a positive regulator for ATP citrate lyase?

A

Glucose, insulin

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11
Q

What is a negative regulator for ATP citrate lyase?

A

PUFA, Leptin

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12
Q

How can malate be transported into mitochondria?

A

Malate alpha ketoglutarate transporter or being converted to pyruvate

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13
Q

How is acetyl CoA converted into malonyl CoA?

A

Acetyl CoA carboxylase (ACC)

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14
Q

What cofactor is needed for acetyl CoA carboxylase to function?

A

Biotin (B7)

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15
Q

What does ACC do?

A

Adds a CO2 to acetyl CoA

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16
Q

When ACC is dimeric it is ___________

A

Inactive

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17
Q

When ACC is polymeric it is ____________

A

Active

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18
Q

ACC is positively regulated by:

A

Citrate, insulin

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19
Q

ACC is negatively regulated by:

A

Glucagon, epinephrine, high AMP, palmitate, PUFA

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20
Q

What inhibits carnitine acyltransferase (rate limiting step in FA degradation) ?

A

Malonyl CoA

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21
Q

Where does the reactions of fatty acid synthesis occur ?

A

Fatty acid synthase complex

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22
Q

What is a positive regulator on the fatty acid synthase?

A

Insulin, glucocorticoid hormones

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23
Q

What is a negative regulator of fatty acid synthase?

A

PUFA

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24
Q

What is the FA synthase composed of?

A

2 identical dimers

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25
How many active enzymes does each dimer have in a FA synthase?
7 enzymes
26
How many proteins does a FA synthase dimer carry?
1: acyl carrier protein (ACP)
27
How does the reaction catalyzed by fatty acid synthase organize itself using: Condensation Reduction Dehydration
1. Condensation 2. Reduction 3. Dehydration 4. Reduction
28
T/F | Gene expression fo the enzymes is induced by low fat, high carb diets
True
29
When ATP citrate lyase is phosphorylated, is it active or inactive?
Active
30
What enzyme does insulin change in ACC to potivitvely regulate it?
Protein phosphatase
31
What enzyme does epinephrine alter to negatively regulate ACC?
Protein kinase A
32
What enzyme does glucagon alter to negatively regulate ACC?
Protein kinase A
33
What enzyme does AMP alter to negatively regulate ACC?
AMP kinase (energy sensor)
34
When ACC is phosphorylated it is active or inactive?
Inactive
35
With FA synthase, the presence of phosphorylated sugars increase or decrease activity?
Increase
36
Palmitate converted to longer chain fatty acids in smooth endoplasmic reticulum or mitochondria is known as _____________
Elongation
37
Which organ needs longer fatty acids?
Brain
38
What is used as a reducing power when synthesizing FA?
NADPH
39
The smooth endoplasmic uses ______________ as a carbon donor
Malonyl CoA
40
The mitochondria uses ______________ as carbon donor
Acetyl CoA
41
The introduction of double bonds in FA is known as ___________
Desaturation
42
Desaturation occurs in the SER, uses NADPH and oxygen, catalyzed by _________________
Acyl CoA Desaturases
43
Humans have _________ desaturases
4 (4,5,6,9)
44
Double bonds between carbons can be introduced inbetween _______, _______, _______, ________
4,5,6,9
45
FA cant be synthesized past _______ in humans
Carbons 9 & 10
46
Omega 3 and omega 6 are known as _______________. They need to be ingested as the precursors: ____________ & _____________
Essential fatty acids | Linoleic Acid & linoleic acids
47
Triacylglycerols (TAGS) contain about _____________ times as much energy as carbs
6.75
48
TAG packaged with ________ to form VLDL and secreted into blood
Apoproteins
49
Glucose, glycerol, and fatty acids are ______________ for TAG
Precursors
50
____________ is used as backbone for TAG synthesis
Glycerol-3-phosphate
51
Intestinal enzymes called _________ digest TAGS
Lipases
52
Breakdown depends on __________ of fatty acids in TAG
Length
53
Suspension into small particles in the aqueous enviroment
Emulsification
54
Fats are emulsified by _______ in the small intestines
Bile salt
55
T/F | Bile salts are amphipathic
True
56
T/F | Emulsification decreases surface area of fats
False | It increases
57
What enzyme digest all lengths of FA in TAGs?
Pancreatic lipase
58
The biles salts breaks down fats into FFA and _____________
2 monoacylglycerol (2MAG)
59
In the synthesis of chylomicrons the FFA and MAGs are condensed to form _______
TAG
60
The TAGs are packaged to form _________
Lipoprotein called “chylomicrons”
61
Chylomicrons contain:
Apoproteins, phospholipids, cholesterol, and fat soluble vitamins
62
A major apoproteins is
APO B 48
63
Nascent chylomicrons are released into the ________ then then the blood stream
Lymph
64
Nascent chylomicrons secreted by intestinal epithelial cells by ____________
Exocytosis
65
Chylomicrons enter the blood via the ________
Thoracic duct
66
Accept proteins from HDL within lymph and blood convert into ________________
Mature chylomicrons
67
ApoE is found in the _______
Liver cells
68
ApoCII is found in the ________
Muscle and adipose tissue
69
T/F | Breakdown of TAGS stored in adipose tissue
True
70
In fatty acid oxidation, how many phases are there?
2 | Phase I and phase II
71
In phase I of fatty acid oxidation, what happens?
Fatty acid activation | -occurs in cytosol
72
In phase II of fatty Acid oxidation, what happens?
Beta-oxidation | -primarily occurs in mitochondrial matrix
73
What are the four steps of beta oxidation of fatty acids?
1. Acyl CoA dehydrogenase (ACAD) 2. Enoyl CoA hydratase 3. B hydroxy acyl CoA dehydrogenase 4. Acyl CoA Acyl transferase (ketothiolase)
74
What is the order of reaction in beta oxidation: Oxidation Hydration Thiolysis
``` Oxidation Hydration Oxidation Thiolysis (Repeat 7 times) ```
75
How much ATP does FADH2 generate?
1.5 (times 7= 10.5)
76
How much ATP does NADH generate?
2.5 (time 7 = 17.5)
77
How much ATP does Acetyl CoA generate?
10 (time 8 =80)
78
The net production of ATP from catabolism of palmitic acid is _______
106 ATP
79
Odd numbered double bonds in fatty acids are handled by __________
Isomerase
80
Even numbered double bonds are handled by ___________ & ___________
Isomerase & reductase
81
Odd chains give rise to prpionyl CoA and acetyl coa, propionyl coa is converted to ____________ and then enters the TCA cycle.
Succinyl CoA
82
The conversion of propionyl CoA to succinyl CoA requires __________ vitamin
B12 (cobalamin)
83
Water soluble and transportable form of acetyl CoA
Ketone bodies
84
Acetoacetate Beta hydroxybutyrate Acetone Are all what type of ketone?
Acidic
85
In what order do these go for diabetic ketosis? - No Glucose - blood pH drops - coma and death - free fatty acids are released - ketone bodies formed - oAA levels drop - CAC slows
1. No glucose 2. OAA levels drop 3. CAC slows 4. Free fatty acids are released 5. Ketone bodies form 6. Blood pH drops 7. Death

Biochemistry (9 decks)

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