登录

Organisms harvest energy from food, but this energy cannot be directly used by cells. Cells convert the energy stored in nutrients into a more usable form: adenosine triphosphate (ATP).

ATP stores energy in chemical bonds that can be quickly released when needed. Cells produce energy in the form of ATP through the process of cellular respiration. Although much of the energy from cellular respiration is released as heat, some of it is used to make ATP.

During cellular respiration, several oxidation-reduction (redox) reactions transfer electrons from organic molecules to other molecules. Here, oxidation refers to electron loss and reduction to electron gain. The electron carriers NAD+ and FAD and their reduced forms, NADH and FADH2, respectively, are essential for several steps of cellular respiration.

Aerobic respiration requires oxygen and generates ATP by breaking down glucose and oxygen into carbon dioxide and water. Some prokaryotes use anaerobic respiration, which does not require oxygen. Both aerobic and anaerobic respiration begins with glycolysis, which can occur without oxygen. Glycolysis breaks down glucose into pyruvate, yielding ATP. In the absence of oxygen, pyruvate ferments, producing NAD+ for continued glycolysis. Importantly, several types of yeast carry out alcoholic fermentation. Human muscle cells can use lactic acid fermentation when oxygen is depleted. Anaerobic respiration ends with fermentation.

Aerobic respiration, however, continues with pyruvate oxidation. Pyruvate oxidation generates acetyl-CoA, which enters the citric acid cycle. The citric acid cycle consists of several redox reactions that release the bond energy of acetyl-CoA, producing ATP and the reduced electron carriers NADH and FADH2.

The final stage of cellular respiration, oxidative phosphorylation, generates most of the ATP. NADH and FADH2 pass their electrons through the electron transport chain. The electron transport chain releases energy that is used to expel protons, creating a proton gradient that enables ATP synthesis.

Most organisms use aerobic (oxygen-requiring) respiration, which produces much more ATP than anaerobic respiration.

Tags

Cellular RespirationCatabolic ProcessOrganic MoleculesElectron Transport ChainOxygenCarbon DioxideWaterHeatATPGlucoseEquationGlycolysisPyruvate OxidationCitric Acid CycleOxidative PhosphorylationMitochondriaFlagellar MovementMuscle ContractionATP ProductionNutrientsAdenosine Triphosphate ATPChemical BondsOxidation

来自章节 8:

article

Now Playing

8.11 : Introduction to Cellular Respiration

Cellular Respiration

171.5K Views

article

8.1 : 什么是糖酵解?

Cellular Respiration

162.2K Views

article

8.2 : 糖酵解的能量需求步骤

Cellular Respiration

162.2K Views

article

8.3 : 糖酵解的能量释放步骤

Cellular Respiration

137.9K Views

article

8.4 : 丙酮酸氧化

Cellular Respiration

157.3K Views

article

8.5 : 柠檬酸循环

Cellular Respiration

149.7K Views

article

8.6 : 电子传输链

Cellular Respiration

95.9K Views

article

8.7 : 化学渗透

Cellular Respiration

96.0K Views

article

8.8 : 电子载体

Cellular Respiration

83.5K Views

article

8.9 : 发酵

Cellular Respiration

112.5K Views

article

8.10 : 饮食联系

Cellular Respiration

49.5K Views

article

8.12 : 柠檬酸循环的产品

Cellular Respiration

97.7K Views

article

8.13 : 糖酵解的结果

Cellular Respiration

98.0K Views

article

8.14 : ATP 产量

Cellular Respiration

68.1K Views

JoVE Logo

政策

使用条款

隐私

科研

教育

关于 JoVE

版权所属 © 2025 MyJoVE 公司版权所有,本公司不涉及任何医疗业务和医疗服务。