Bio1332 Biochemistry - Lecture Nineteen - Fatty Acid Metabolism

FALSE.
Fatty acids normally have an even number of carbon atoms.

Fatty acids are oxidized in the mitochondria. This organelle is responsible for generating energy through the process of cellular respiration. Fatty acids are broken down into acetyl-CoA molecules, which enter the citric acid cycle in the mitochondria to produce ATP. The mitochondria have specialized enzymes and transporters that facilitate the oxidation of fatty acids and the production of energy.

Fatty acid synthesis occurs in the cytoplasm. This process involves the conversion of acetyl-CoA into fatty acids, which are essential for the synthesis of lipids. The enzymes required for fatty acid synthesis are located in the cytoplasm, specifically in a complex called the fatty acid synthase complex. This complex catalyzes the step-by-step synthesis of fatty acids, using acetyl-CoA as the building block. Therefore, the cytoplasm is the correct location for fatty acid synthesis to occur.

Fatty acids are often conjugated with glycerol to form lipids. Glycerol is a three-carbon alcohol that serves as the backbone for triglycerides, which are the most common type of lipid found in our bodies. When three fatty acids are esterified to a glycerol molecule, a triglyceride is formed. This process is essential for the storage and transport of energy in the form of fats. Glycerols, on the other hand, is not a correct term and does not accurately describe the conjugation of fatty acids with glycerol.

During β-oxidation, fatty acids are broken down into acetyl-CoA molecules. Each round of β-oxidation produces one molecule of acetyl-CoA, which enters the citric acid cycle and generates 3 molecules of NADH and 1 molecule of FADH2. These electron carriers go on to produce ATP through oxidative phosphorylation. In total, 7 rounds of β-oxidation would produce 7 acetyl-CoA molecules, resulting in the production of 21 NADH and 7 FADH2. Considering the ATP yield from oxidative phosphorylation, which is 2.5 ATP per NADH and 1.5 ATP per FADH2, the total ATP produced would be 106 ATP.

Plants and fungi have the ability to convert acetyl coenzyme A into sugars through a process known as photosynthesis. This metabolic pathway allows them to utilize sunlight, carbon dioxide, and water to produce glucose, which can then be used as an energy source for growth and other cellular functions. On the other hand, animals lack the necessary enzymes and mechanisms to perform photosynthesis, and therefore cannot convert acetyl coenzyme A into sugars. Hence, the statement that animals cannot convert acetyl coenzyme A into sugars is true.

Fatty acid activation requires the attachment of a molecule called Coenzyme A (CoA) to the fatty acid, which requires the hydrolysis of ATP to AMP and pyrophosphate. This process occurs twice, resulting in the expenditure of 2 ATP molecules. Therefore, the correct answer is 2 ATPs.

Triacylglycerol (TAG) is a type of lipid molecule that consists of three fatty acids linked to a glycerol molecule. The bond between the fatty acids and glycerol is called an ester bond. Ester bonds are formed through a condensation reaction between the carboxyl group of the fatty acid and the hydroxyl group of the glycerol. This linkage allows for the storage of large amounts of energy in the form of TAGs, making them an important energy reserve in organisms.

The first step in fatty acid synthesis is the synthesis of malonyl coA, which is catalyzed by the enzyme Acetyl coA carboxylase. The alternative answer, malonyl coenzyme A, Acetyl coenzyme A carboxylase, is incorrect as the correct term is malonyl coA, not malonyl coenzyme A. Acetyl coA carboxylase is the enzyme responsible for catalyzing the synthesis of malonyl coA.

Triacylglycerol lipase is the enzyme responsible for catalyzing the breakdown of triacylglycerols (TAGs) in adipose tissue. This enzyme breaks down TAGs into glycerol and fatty acids, which can then be used as a source of energy. Adipose tissue, also known as fat tissue, stores excess energy in the form of TAGs, and the action of triacylglycerol lipase helps release this stored energy when needed by the body.

Mammals are unable to produce glucose directly from acetyl CoA, but they can synthesize glucose from propionyl CoA or propionyl coenzyme A. This is achieved through a metabolic pathway called gluconeogenesis, which allows the conversion of non-carbohydrate sources, such as certain amino acids and organic acids, into glucose. Therefore, propionyl CoA or propionyl coenzyme A can serve as precursors for glucose production in mammals.