Question

Oxidation of Arachidic Acid How many turns of the fatty acid oxidation cycle are required for complete oxidation of arachidic acid \((20: 0)\) to acetyl-CoA?

Short answer

9 cycles are needed.

Step-by-step solution

Understanding the Problem

Arachidic acid is a saturated fatty acid with a formula of \(C_{20}H_{40}O_2\). We need to determine the number of cycles of beta-oxidation needed to break down the entire molecule into acetyl-CoA units.

Determine the Number of Carbon Atoms

Arachidic acid has 20 carbon atoms, as indicated by the notation \((20: 0)\). Each acetyl-CoA unit produced by beta-oxidation has 2 carbon atoms.

Calculate Number of Acetyl-CoA Units

The total number of acetyl-CoA units formed from a fatty acid is the total number of carbon atoms divided by 2. For arachidic acid, this calculation is \( \frac{20}{2} = 10 \) acetyl-CoA units.

Calculate Number of Beta-Oxidation Cycles

Each round of the beta-oxidation cycle shortens the fatty acid chain by 2 carbon atoms and produces 1 acetyl-CoA. Since one cycle produces 1 acetyl-CoA, and we need 10 acetyl-CoA units, the number of cycles required is \(10 - 1 = 9\). This is because the last reaction does not require an entire cycle.

Key concepts

Arachidic Acid

Arachidic acid is a long-chain saturated fatty acid, comprising 20 carbon atoms. It is represented by the notation \((20:0)\), signifying it has no double bonds. As a saturated fatty acid, it has a straight chain structure, which impacts how it is metabolized in biological systems.
This compound is found in notable quantities in peanut oil and other plant oils. Its structure and properties play a significant role in determining its function and metabolism.
Being saturated, arachidic acid is solid at room temperature, contributing to the texture and consistency of fats where it is present. These properties also influence how it undergoes the process of fatty acid oxidation.

Acetyl-CoA

Acetyl-CoA is a crucial molecule in metabolism, acting as a key metabolic intermediate. It is formed during the breakdown of carbohydrates, fatty acids, and amino acids and participates in several important biochemical pathways.
In the context of fatty acid oxidation, acetyl-CoA is the end product of each cycle of beta-oxidation. It consists of a two-carbon acetyl group linked to coenzyme A, which helps it enter the citric acid cycle, where it contributes to energy production.
Acetyl-CoA plays essential roles not only in energy metabolism but also in the synthesis of lipids and other molecules. Its versatility makes it indispensable in the metabolic pathways of living organisms.

Fatty Acid Oxidation

Fatty acid oxidation involves breaking down fatty acids to generate energy. This occurs primarily in the mitochondria through a process called beta-oxidation. Long-chain fatty acids like arachidic acid undergo this breakdown to produce acetyl-CoA.
The process involves several cycles, each shortening the fatty acid chain by two carbon atoms while producing one molecule of acetyl-CoA. Once acetyl-CoA is formed, it enters the citric acid cycle, aiding in ATP production.
Fatty acid oxidation is crucial for maintaining energy balance, especially during periods of fasting, when the body relies more heavily on stored fats to meet its energy demands.

Biochemistry Education

Biochemistry education equips students with a deep understanding of the chemical processes underlying biological systems. It covers a wide range of topics, including metabolism, enzyme function, and molecular biology.
Learning about processes like fatty acid oxidation is essential, as they form the basis for understanding how organisms obtain and use energy. It helps students appreciate the intricate biochemical networks that sustain life.
Educators aim to provide tools and techniques to analyze and solve biochemical problems. This includes grasping the mechanics of pathways like beta-oxidation, understanding molecular structures, and interpreting metabolic data.