Anatomy & Physiology: The Unity of Form and Function, 7th Edition

Published by McGraw-Hill Education
ISBN 10: 0073403717
ISBN 13: 978-0-07340-371-7

Chapter 26 - Section 26.2 - Study Guide - Assess Your Learning Outcomes - Page 1024: 10

Answer

The efficiency of aerobic respiration refers to the ratio of the actual energy produced in the form of ATP (\text{adenosine triphosphate}) to the potential energy available in the glucose molecule (\text{C}_6\text{H}_{12}\text{O}_6) that serves as the starting substrate for the process. This efficiency is not \(100\%\) due to energy losses at various stages of cellular respiration, such as heat generation and inefficiencies in energy conversion. The efficiency of aerobic respiration can be calculated using the following formula: \[ \text{Efficiency (\%)} = \left( \frac{\text{ATP produced}}{\text{Energy available in glucose}} \right) \times 100 \] The potential energy available in a glucose molecule can be estimated based on the number of ATP molecules that can theoretically be generated from its complete oxidation through glycolysis, the citric acid cycle, and oxidative phosphorylation. For one molecule of glucose, the theoretical maximum ATP yield through oxidative phosphorylation can be calculated as follows: 1. Glycolysis (net ATP): \(2\) ATP 2. Citric Acid Cycle (2 cycles): Approximately \(2\) ATP (considering \(1\) ATP equivalent from GTP conversion) from substrate-level phosphorylation 3. NADH from glycolysis (per glucose): \(2\) NADH \(\times 2.5\) ATP/NADH = \(5\) ATP 4. NADH from citric acid cycle (per glucose): \(6\) NADH \(\times 2.5\) ATP/NADH = \(15\) ATP 5. FADH\(_2\) from citric acid cycle (per glucose): \(2\) FADH\(_2\) \(\times 1.5\) ATP/FADH\(_2\) = \(3\) ATP Total ATP from oxidative phosphorylation (per glucose) = \(2 + 2 + 5 + 15 + 3 = 27\) ATP Therefore, the theoretical maximum ATP yield from one molecule of glucose through oxidative phosphorylation is \(27\) ATP. Now, you can calculate the efficiency using the formula: \[ \text{Efficiency (\%)} = \left( \frac{\text{ATP produced}}{\text{Energy available in glucose}} \right) \times 100 \] \[ \text{Efficiency (\%)} = \left( \frac{27 \text{ ATP}}{\text{Energy available in glucose}} \right) \times 100 \] Please note that calculating the actual efficiency of aerobic respiration in a biological system is quite complex due to various factors, including differences in cell types, metabolic pathways, and energy utilization for other cellular processes. The calculated efficiency provides a theoretical estimate and does not account for real-world inefficiencies and energy losses.

Work Step by Step

The efficiency of aerobic respiration refers to the ratio of the actual energy produced in the form of ATP (\text{adenosine triphosphate}) to the potential energy available in the glucose molecule (\text{C}_6\text{H}_{12}\text{O}_6) that serves as the starting substrate for the process. This efficiency is not \(100\%\) due to energy losses at various stages of cellular respiration, such as heat generation and inefficiencies in energy conversion. The efficiency of aerobic respiration can be calculated using the following formula: \[ \text{Efficiency (\%)} = \left( \frac{\text{ATP produced}}{\text{Energy available in glucose}} \right) \times 100 \] The potential energy available in a glucose molecule can be estimated based on the number of ATP molecules that can theoretically be generated from its complete oxidation through glycolysis, the citric acid cycle, and oxidative phosphorylation. For one molecule of glucose, the theoretical maximum ATP yield through oxidative phosphorylation can be calculated as follows: 1. Glycolysis (net ATP): \(2\) ATP 2. Citric Acid Cycle (2 cycles): Approximately \(2\) ATP (considering \(1\) ATP equivalent from GTP conversion) from substrate-level phosphorylation 3. NADH from glycolysis (per glucose): \(2\) NADH \(\times 2.5\) ATP/NADH = \(5\) ATP 4. NADH from citric acid cycle (per glucose): \(6\) NADH \(\times 2.5\) ATP/NADH = \(15\) ATP 5. FADH\(_2\) from citric acid cycle (per glucose): \(2\) FADH\(_2\) \(\times 1.5\) ATP/FADH\(_2\) = \(3\) ATP Total ATP from oxidative phosphorylation (per glucose) = \(2 + 2 + 5 + 15 + 3 = 27\) ATP Therefore, the theoretical maximum ATP yield from one molecule of glucose through oxidative phosphorylation is \(27\) ATP. Now, you can calculate the efficiency using the formula: \[ \text{Efficiency (\%)} = \left( \frac{\text{ATP produced}}{\text{Energy available in glucose}} \right) \times 100 \] \[ \text{Efficiency (\%)} = \left( \frac{27 \text{ ATP}}{\text{Energy available in glucose}} \right) \times 100 \] Please note that calculating the actual efficiency of aerobic respiration in a biological system is quite complex due to various factors, including differences in cell types, metabolic pathways, and energy utilization for other cellular processes. The calculated efficiency provides a theoretical estimate and does not account for real-world inefficiencies and energy losses.
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