Energy and Respiration: ATP, Glycolysis and Oxidative Phosphorylation | 能量与呼吸：ATP、糖酵解与氧化磷酸化

📚 Energy and Respiration: ATP, Glycolysis and Oxidative Phosphorylation | 能量与呼吸：ATP、糖酵解与氧化磷酸化

In A-level Biology, energy and respiration is the topic that explains how cells release chemical energy from organic fuels such as glucose and trap it in a usable form as ATP. This process links the oxidation of food molecules to the synthesis of ATP, which then powers almost every activity in the cell.

在A-level生物课程中，能量与呼吸解释了细胞如何从葡萄糖等有机燃料中释放化学能，并将其以ATP这一可利用形式储存起来。该过程将食物分子的氧化与ATP的合成联系起来，而ATP随后驱动细胞中几乎所有的生命活动。

1. Why Organisms Need Energy | 生物为何需要能量

All living cells need a continuous supply of energy to carry out work. Energy is required for active transport across membranes, anabolic reactions such as protein synthesis and DNA replication, muscle contraction, cell division, maintenance of body temperature in endotherms, and nerve impulse transmission. In plants, energy is also used for active loading of sucrose in phloem and for mineral ion uptake.

所有活细胞都需要持续的能量供应来完成各种生命活动。能量用于跨膜主动运输、蛋白质合成和DNA复制等合成代谢反应、肌肉收缩、细胞分裂、恒温动物维持体温以及神经冲动传导。在植物中，能量还用于韧皮部蔗糖的主动装载和矿质离子的吸收。

2. ATP as the Universal Energy Currency | ATP作为通用的能量货币

ATP is a nucleotide derivative consisting of adenine, ribose, and three phosphate groups. Hydrolysis of the terminal phosphate bond is catalysed by ATPase and can be written as ATP + H₂O → ADP + Pᵢ. This releases about 30.5 kJ mol⁻¹ under standard conditions and provides energy for energy-requiring reactions. ATP is the immediate energy donor in cells, not a long-term store; glucose and lipids store much more energy per gram.

ATP是一种核苷酸衍生物，由腺嘌呤、核糖和三个磷酸基团组成。末端磷酸键的水解由ATP酶催化，可写为ATP + H₂O → ADP + Pᵢ。该反应在标准条件下释放约30.5 kJ mol⁻¹的能量，为需能反应提供能量。ATP是细胞中直接的能量供体，而不是长期储能物质；葡萄糖和脂质每克储存的能量多得多。

3. Overview of Cellular Respiration | 细胞呼吸概述

Cellular respiration is the controlled release of energy from organic compounds in cells. Aerobic respiration requires oxygen and can be summarised as C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy. It occurs in four main stages: glycolysis in the cytoplasm, the link reaction and the Krebs cycle in the mitochondrial matrix, and oxidative phosphorylation on the inner mitochondrial membrane. The energy released is used to synthesise ATP from ADP and inorganic phosphate.

细胞呼吸是细胞中有机化合物受控释放能量的过程。有氧呼吸需要氧气，总反应可概括为C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 能量。它分为四个主要阶段：细胞质中的糖酵解、线粒体基质中的连接反应和克雷布斯循环，以及线粒体内膜上的氧化磷酸化。释放的能量用于从ADP和无机磷酸合成ATP。

4. Glycolysis: Glucose Splitting | 糖酵解：葡萄糖分解

Glycolysis occurs in the cytoplasm and does not require oxygen. Glucose is first phosphorylated using two ATP molecules to form hexose bisphosphate. This molecule is split into two molecules of triose phosphate. Each triose phosphate is oxidised by NAD⁺ to produce reduced NAD, and phosphate groups are transferred to ADP to form ATP by substrate-level phosphorylation. Overall, glycolysis produces a net gain of two ATP, two reduced NAD, and two pyruvate per glucose.

糖酵解发生在细胞质中，不需要氧气。葡萄糖首先利用两分子ATP磷酸化，形成己糖二磷酸。这个分子分裂为两分子丙糖磷酸。每个丙糖磷酸被NAD⁺氧化生成还原型NAD，同时磷酸基团通过底物水平磷酸化转移给ADP形成ATP。总体而言，每分子葡萄糖经糖酵解净产生两分子ATP、两分子还原型NAD和两分子丙酮酸。

5. Link Reaction and Coenzyme A | 连接反应与辅酶A

In aerobic respiration, each pyruvate enters the mitochondrial matrix by active transport. The link reaction removes one carbon atom as carbon dioxide and removes hydrogen atoms that reduce NAD⁺. The remaining two-carbon acetyl group combines with coenzyme A to form acetyl coenzyme A. For each glucose molecule, the link reaction produces two acetyl CoA, two CO₂, and two reduced NAD.

在有氧呼吸中，每个丙酮酸通过主动运输进入线粒体基质。连接反应脱去一个碳原子生成二氧化碳，并脱下氢原子使NAD⁺还原。剩余的二碳乙酰基与辅酶A结合，形成乙酰辅酶A。每分子葡萄糖经连接反应产生两分子乙酰辅酶A、两分子CO₂和两分子还原型NAD。

6. Krebs Cycle: the Metabolic Hub | 克雷布斯循环：代谢枢纽

Acetyl CoA enters the Krebs cycle in the mitochondrial matrix. Its two-carbon acetyl group combines with four-carbon oxaloacetate to form six-carbon citrate. Citrate is then decarboxylated and dehydrogenated in a series of reactions that regenerate oxaloacetate. One turn of the cycle produces three reduced NAD, one reduced FAD, one ATP, and two CO₂. Because each glucose produces two acetyl CoA, the cycle turns

Published by TutorHao | A-Level Biology Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）