Concept explainers
(a)
Interpretation:
Whether or not cholesterol produced from acetyl CoA (1) can be produced in a one-step process, (2) can be produced in a multistep process, or (3) cannot be produced from acetyl CoA has to be indicated.
Concept introduction:
Fatty acids are molecules that are long hydrocarbon chain of
The fatty acids are broken down to provide energy. The breakdown of fatty acids is a three parts process. In the first part, the fatty acid is activated. In the second part, the transportation of fatty acid into the mitochondrial matrix is facilitated by a shuttle mechanism. In the third part, the fatty acid is readily oxidized, cycling through a series of four reactions. In these series of reactions, acyl CoA is degraded to acetyl CoA. This pathway is termed as the β-oxidation pathway. Acetyl CoA, FADH2, and NADH are produced in this reaction.
Cholesterol is an important component of cell membranes. It is used as the precursor for sex hormones, bile salts, and adrenal hormones. The biosynthesis of cholesterol occurs in the liver. It is a C27 molecule. The structure of cholesterol is as follows:
(b)
Interpretation:
Whether or not acetoacetyl CoA produced from acetyl CoA (1) can be produced in a one-step process, (2) can be produced in a multistep process, or (3) cannot be produced from acetyl CoA has to be indicated.
Concept introduction:
Fatty acids are molecules that are long hydrocarbon chain of carboxylic acid. They are building blocks of fat in humans and animals.
The fatty acids are broken down to provide energy. The breakdown of fatty acids is a three parts process. In the first part, the fatty acid is activated. In the second part, the transportation of fatty acid into the mitochondrial matrix is facilitated by a shuttle mechanism. In the third part, the fatty acid is readily oxidized, cycling through a series of four reactions. In these series of reactions, acyl CoA is degraded to acetyl CoA. This pathway is termed as the β-oxidation pathway. Acetyl CoA, FADH2, and NADH are produced in this reaction.
Ketogenesis is a
cleavage and hydrogenation to produce ketone bodies.
(c)
Interpretation:
Whether or not malonyl CoA produced from acetyl CoA (1) can be produced in a one-step process, (2) can be produced in a multistep process, or (3) cannot be produced from acetyl CoA has to be indicated.
Concept introduction:
Fatty acids are molecules that are long hydrocarbon chain of carboxylic acid. They are building blocks of fat in humans and animals.
The fatty acids are broken down to provide energy. The breakdown of fatty acids is a three parts process. In the first part, the fatty acid is activated. In the second part, the transportation of fatty acid into the mitochondrial matrix is facilitated by a shuttle mechanism. In the third part, the fatty acid is readily oxidized, cycling through a series of four reactions. In these series of reactions, acyl CoA is degraded to acetyl CoA. This pathway is termed as theβ-oxidation pathway. Acetyl CoA, FADH2, and NADH are produced in this reaction.
Lipogenesis is the process employed for the synthesis of fatty acid. The starting precursor for the synthesis is acetyl CoA. The enzyme employed for the process is fatty acid synthase. It is a multienzyme complex that ties the reaction responsible for the synthesis of fatty acid.
A cyclic process occurs in the enzyme fatty acid synthase. One turn of this cyclic process
constitutes four reactions. The various intermediates formed in the process are associated
with a carrier protein known as ACP.
(d)
Interpretation:
Whether or not pyruvate produced from acetyl CoA (1) can be produced in a one-step process, (2) can be produced in a multistep process, or (3) cannot be produced from acetyl CoA has to be indicated.
Concept introduction:
Fatty acids are molecules that are long hydrocarbon chain of carboxylic acid. They are building blocks of fat in humans and animals.
The fatty acids are broken down to provide energy. The breakdown of fatty acids is a three parts process. In the first part, the fatty acid is activated. In the second part, the transportation of fatty acid into the mitochondrial matrix is facilitated by a shuttle mechanism. In the third part, the fatty acid is readily oxidized, cycling through a series of four reactions. In these series of reactions, acyl CoA is degraded to acetyl CoA. This pathway is termed as the β-oxidation pathway. Acetyl CoA, FADH2, and NADH are produced in this reaction.
Pyruvate is the end product in the glycolysis. In the presence of oxygen, pyruvate is converted to acetyl CoA by the involvement of pyruvate dehydrogenase complex enzymes in the human body.
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Chapter 25 Solutions
EBK GENERAL, ORGANIC, AND BIOLOGICAL CH
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