Name: atp powers cellular transport and reactions
Uploaded: 2025-05-22T09:05:36.000Z
Duration: 1 min 31 s
Channel: JoVE

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High School

Life Science

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms: Structures and Processes

HS-LS1-5

ATP Energy Storage and Release

三磷酸腺苷（ATP）是细胞内最重要的能量载体，可为多种生物化学过程提供能量。
ATP 是一种有机化合物，由一个腺苷分子（用 A 表示）与三个磷酸基团（用 P 表示）相连构成。这三个磷酸基团之间通过两个高能磷酸酐键连接。这些键的水解反应可释放约 46 至 54 千焦/摩尔的自由能，具体数值取决于细胞内的条件。
由于将磷酸基团连接到ADP分子上在能量上是不利的，细胞需通过光合作用或细胞呼吸获取能量，以形成ADP与第三个磷酸基团之间的磷酸酐键。
相反，在需要能量时，ATP 会水解生成无机磷酸盐和一分子 ADP。这一在能量上有利的反应可与其他不利反应相偶联，其中释放的磷酸基团被转移至反应物，从而形成新的产物。
此外，ATP水解释放的能量可驱动跨膜转运溶质的泵，同时也为肌肉收缩和神经元信号传导通路提供动力。

atp 的能量储存和释放

ATP 是一种极其不稳定的分子。除非将其迅速用于做功，否则 ATP 会自发分解成 ADP 和无机磷酸盐（Pi），在此过程中释放的自由能会以热量的形式散失。ATP 水解过程中所释放的能量用于在细胞内做功，这取决于一种称为能量耦合的过程。细胞能够将 ATP 水解的放能反应与吸能反应结合起来，从而使得它们能够继续进行。

使用 ATP 能量耦合的一个例子是：对细胞功能极其重要的跨膜离子泵。这种钠钾泵（Na^+/K^+ 泵）能够将钠离子从细胞中流出，将钾离子流入到细胞中。由于细胞过程会定期向细胞输入大量的钠离子，并同时向细胞输入大量的钾离子，因此细胞中的很大一部分 ATP 可以用来为该泵提供能量。钠钾泵能够通过不断的工作来稳定细胞中钠离子和钾离子的浓度。为了使泵能够运转一个周期（输出三个钠离子并输入两个钾离子），则必须水解一分子 ATP。当 ATP 发生水解时，ATP 中的 γ 磷酸盐则会被转移到泵蛋白中。

这种磷酸基团与分子结合的过程被称为磷酸化。这与大多数 ATP 水解的过程是一样的，ATP 中的磷酸盐将会被转移到另一个分子上。在磷酸化状态下，钠钾泵具有更多的自由能，并被触发进行构象变化的过程。这种变化使其能够将钠离子释放到细胞外部。然后，它会与细胞外的钾离子进行结合，并通过另一种构象变化来使得磷酸盐能够与泵发生分离。磷酸盐的释放会引发钾离子释放到细胞内部。从本质上来讲，水解 ATP 所释放的能量与为泵提供动力和运输钠离子和钾离子所需的能量相结合。ATP 能够通过磷酸化这种基本形式的能量偶联来完成细胞工作。

通常，在细胞代谢反应（例如营养物质的合成和分解）过程中，某些分子的构象必须能够发生轻微改变，才能能够成为反应过程中下一步的底物。其中的一个例子是在糖酵解的过程中（即细胞呼吸的第一步）。在第一步中，需要 ATP 来磷酸化葡萄糖，从而产生一种高能但不稳定的中间体。这种磷酸化反应能够产生构象变化，从而使磷酸化的葡萄糖分子转化为磷酸化的果糖。果糖是糖酵解继续进行的必要中间体。在这里，ATP 水解的放能反应能够与葡萄糖磷酸化的放能反应相结合，从而构成了这一途径的中间过程。ATP 内的磷酸键断裂所释放的能量将会再次被用于另一个分子的磷酸化，从而产生了一个不稳定的中间体，并为重要的构象变化提供了动力。

ATP 的能量储存和释放

ATP 是一种高度不稳定的分子。除非被迅速用于做功，否则 ATP 会自发解离为 ADP 和无机磷酸盐（Pi），并释放出自由能。

Education

教育

JoVE Core

Cell Biology

细胞生物学

Unit 1

第一单元

Energy and Catalysis

能量与催化

KEY TERMS AND CONCEPTS

关键术语与概念

atp powers cellular transport and reactions

ATP powers cellular transport and many reactions by transferring energy through phosphorylation. ATP is a highly unstable molecule. If it is not used quickly, it breaks down into ADP and inorganic phosphate, and the released energy is lost as heat.

Cells use ATP through energy coupling. This means the exergonic reaction of ATP hydrolysis is linked to an endergonic reaction so the reaction can move forward. One major example is the sodium-potassium pump, a transmembrane ion pump that is vital for cell function.

The sodium-potassium pump moves sodium out of the cell and potassium into the cell. Cells spend a large amount of ATP on this pump because sodium and potassium are regularly moved in opposite directions across the membrane. To complete one cycle, the pump exports three sodium ions and imports two potassium ions, and one ATP molecule must be hydrolyzed.

During ATP hydrolysis, the gamma phosphate is transferred to the pump protein. This is called phosphorylation, which means a phosphate group binds to a molecule. In the phosphorylated state, the pump has more free energy and changes shape. That shape change lets it release sodium outside the cell. The pump then binds potassium outside the cell, and another shape change removes the phosphate and releases potassium inside the cell.

ATP also helps start steps in cellular metabolism. In glycolysis, which is the first stage of cellular respiration, ATP phosphorylates glucose. This creates a high-energy but unstable intermediate. The phosphorylation also drives a conformational change that helps the molecule become phosphorylated fructose, which is needed for glycolysis to continue. In both examples, ATP hydrolysis is coupled to another reaction by transferring a phosphate group and powering an important change in shape.

ATP Powers Cellular Transport and Reactions

atp-powers-cellular-transport-and-reactions

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ATP powers cellular transport and many reactions by transferring energy through phosphorylation. ATP is a highly unstable molecule. If it is not used quickly, it breaks down into ADP and inorganic phosphate, and the released energy is lost as heat. Cells use ATP through energy coupling. This means the exergonic reaction of ATP hydrolysis is linked to an endergonic reaction so the reaction can move forward. One major example is the sodium-potassium pump, a transmembrane ion pump that is vital...

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ATP Powers Cellular Transport and Reactions | JoVE K12

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ATP Powers Cellular Transport and Reactions

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