In which cellular compartment does the lengthening of fatty acid chains primarily take place in the mammalian liver?
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(D)
Microsomes
2
Which enzyme is crucial for facilitating the movement of acetyl-CoA, the primary building block of fatty acids, from the mitochondria to the cytosol?
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(C)
Citrate lyase
3
The process of fatty acid synthesis is often described as a reductive process. Which of the following molecules provides the necessary reducing power for this process?
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(D)
NADPH
4
Which complex functions as a multifunctional enzyme in higher organisms, playing a key role in fatty acid synthesis?
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(D)
Fatty acid synthase
5
The fatty acid synthase complex carries out how many distinct enzymatic steps?
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(B)
6 sequential enzymatic steps
6
What is the major pathway that generates the reducing equivalents (NADPH) required for the synthesis of fatty acids?
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(A)
Pentose phosphate pathway
7
ACP (acyl carrier protein), a component of fatty acid synthase in both bacteria and mammals, contains which vitamin?
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(D)
Pantothenic acid
8
Which enzyme catalyzes the reaction that converts acetyl-CoA to malonyl-CoA?
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(A)
Acetyl-CoA carboxylase
9
In the pathway of fatty acid synthesis, what is the step that most significantly controls the rate of the overall process?
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(A)
Acetyl-CoA carboxylase step
10
To create an acylCoA derivative with two additional carbon atoms from fatty acyl-CoA, which molecule serves as the source of acetyl units?
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(D)
Malonyl-CoA
11
What cofactor is necessary for the transformation of acetyl-CoA to malonyl-CoA during fatty acid synthesis outside of mitochondria?
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(A)
Biotin
12
Where does the glycerol used for fatty acid esterification primarily originate in fat cells?
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(A)
Primarily from glucose
13
What is the initial intermediate formed in the process of synthesizing triglycerides from glycerol 3-phosphate and acyl-CoA?
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(D)
Phosphatidic acid
14
In which of the following tissues is the activity of the enzyme glycerol kinase notably low?
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(D)
Adipose tissue
15
What is the shared precursor in the creation of both triacylglycerol and phospholipids?
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(A)
1, 2-Diacylglycerol phosphate
16
Which enzyme systems are involved in the synthesis of polyunsaturated fatty acids?
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(A)
Acyl transferase and hydratase
17
Which factor promotes the desaturation and chain elongation system of polyunsaturated fatty acids?
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(A)
Insulin
18
A higher rate of fat production (lipogenesis) is linked to what dietary or hormonal state?
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(A)
High proportion of carbohydrate in diet
19
Which of the following exemplifies enzyme specificity?
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(D)
All of these
20
Phospholipase C cleaves the ester bond, releasing 1, 2-diacylglycerol and a phosphoryl base at which position?
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(D)
3
21
What enzyme facilitates the creation of phosphatidylinositol by attaching inositol to CDP diacylglycerol?
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(C)
CDP-diacylglycerol inositol transferase
22
Which cofactor is necessary for the creation of sphingosine?
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(C)
NADPH+
23
What two molecules combine to create ceramide?
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(B)
Acyl-CoA
24
Where does the synthesis of the amino alcohol sphingosine primarily occur?
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(D)
Endoplasmic reticulum
25
Which hormone decreases the release of free fatty acids from fat tissue?
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(A)
Insulin
26
What is the main way insulin affects fat tissue, specifically regarding enzyme activity?
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(A)
Hormone sensitive lipoprotein lipase
27
In the process of non-shivering thermogenesis, what is the primary mechanism?
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(B)
Fatty acids uncouple oxidative phosphorylation
28
What best characterizes brown adipose tissue?
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(B)
Characterised by high content of mitochondria
29
What substance accumulates in the liver, leading to fatty liver disease?
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(D)
Triacylglycerol
30
What is an example of a lipotropic factor?
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(A)
Choline
31
Which of the following substances is linked to the development of fatty liver?
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(B)
CCl4
32
Where are all the enzymes necessary for cholesterol production primarily located?
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(D)
Endoplasmic reticulum and cytosol
33
What is the primary source of all the carbon atoms in cholesterol?
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(A)
Acetyl-CoA
34
What enzyme facilitates the condensation of two acetyl-CoA molecules into acetoacetyl-CoA?
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(A)
Thiolase
35
What molecule is formed when acetoacetyl-CoA combines with another acetyl-CoA molecule?
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(D)
3-Hydroxy 3-methyl-glutaryl-CoA
36
What enzyme catalyzes the conversion of HMG-CoA to mevalonate through reduction?
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(B)
HMG-CoA reductase
37
What cofactor is essential for the enzyme HMG-CoA reductase during the reduction process?
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(A)
NADPH
38
Which step in cholesterol biosynthesis is key for controlling the rate and site of metabolic regulation?
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(C)
HMG CoA → mevalonate
39
What sterol is directly produced by the cyclization of squalene in mammals?
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(B)
Lanosterol
40
Which enzyme is the rate-limiting factor in the biosynthesis of cholesterol?
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(C)
HMG-CoA reductase
41
Which enzyme's activity is suppressed by cholesterol through a regulatory loop?
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(B)
HMG-CoA reductase
42
Which of the following is known to suppress the function of HMG-CoA reductase?
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(A)
A fungal-derived compound related to mevastatin
43
What is the primary mechanism by which clofibrate, a lipid-lowering medication, achieves its effect?
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(B)
Lowering the release of VLDL particles, which transport triacylglycerol and cholesterol, by the liver
44
In the production of cholesterol, which enzyme's function is disrupted by triparanol?
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(A)
Δ24 Reductase
45
Which hormone's presence is associated with increased activity of HMG-CoA reductase?
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(A)
Insulin
46
Which of the following sterols is the primary one found in fecal matter?
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(A)
Coprostanol
47
The most crucial, or rate-limiting, process in the creation of bile acids involves which of the following?
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(A)
7-Hydroxylase reaction
48
Which of the following conditions is often associated with elevated cholesterol levels?
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(A)
Xanthomatosis
49
In which of these conditions is a decrease in cholesterol levels typically observed?
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(A)
Thyrotoxicosis
50
What is the main source of cholesterol outside of cells that is available for human tissues?
