Name: atp powers cellular work
Uploaded: 2025-05-22T09:05:36.000Z
Duration: 1 min 17 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Chemistry

Matter And Its Interactions

HS-PS1-4

Coupled Reactions

当一个高度放能反应驱动一个吸能反应时，就会发生能量偶联。这种组合反应被称为偶联反应。
细胞利用偶联反应执行多种过程，包括生物合成、离子的主动运输以及机械功。ATP的水解是一种常见的与放能反应偶联的反应，为生物过程提供能量。
例如，谷氨酸与氨生成谷氨酰胺的吸能反应与ATP水解为ADP和无机磷酸盐的放能反应相偶联。
耦合反应的净自由能变化是各个单独反应自由能变化的总和。由于其显著的负值 ΔG 对于ATP水解，总标准自由能变化为-16.3 kJ/mol，反应可以进行。
偶联的生物合成反应通常共享一个共同的不稳定中间产物。在谷氨酰胺的生物合成过程中，ATP 中的磷酸基团转移至谷氨酸形成中间产物谷氨酰磷酸，后者再与氨反应生成谷氨酰胺。

耦合反应

构建和分解复杂分子之类的细胞过程是通过逐步的化学反应来进行的。其中一些化学反应是自发的、是能够释放能量的，而另一些则需要吸收能量才能够得以进行。细胞通常会将释放能量的反应与吸收能量的反应结合起来，以此来执行重要的细胞功能。

三磷酸腺苷或 ATP 分子中的能量很容易被用来做功。ATP 为大多数需要能量的细胞反应来提供动力。细胞能够将 ATP 水解与吸能反应结合起来，使得吸能反应能够继续进行。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。

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反应的底物。例如，在细胞呼吸的最初步骤中，糖分子在葡萄糖酵解的过程中便会发生分解。在第一步中，需要 ATP 对葡萄糖进行磷酸化，从而产生一个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将葡萄糖转化为过程中的磷酸化中间体的放能反应相结合。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。

诸如构建和分解复杂分子等细胞过程是通过逐步的化学反应进行的。其中一些化学反应是……

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 work

ATP powers many kinds of cellular work by coupling energy-releasing reactions to energy-requiring ones. Some reactions happen on their own and release energy. Others need an energy input to move forward. Cells link these reactions so important processes can still occur.

Adenosine triphosphate, or ATP, stores energy that cells can use quickly. ATP hydrolysis is the breaking of ATP, and it releases energy. Cells often use that released energy to drive endergonic reactions, which are reactions that require energy. This coupling helps cells carry out most energy-requiring reactions.

One major example is the sodium-potassium pump, or Na+/K+ pump. This transmembrane ion pump moves sodium out of the cell and potassium into the cell. Many cell processes bring sodium in and potassium out, so a large share of cellular ATP is used to keep these ion levels stable. The pump works constantly to support cell function.

ATP also helps reactions in metabolism, including the first steps of glycolysis, which is part of cellular respiration. In the first step, ATP phosphorylates glucose by adding a phosphate group. This creates a high-energy but unstable intermediate. The phosphorylation causes a conformational change, or shape change, that lets the molecule continue through the pathway.

That shape change allows the phosphorylated glucose to become phosphorylated fructose, which is needed for glycolysis to proceed. Here again, the exergonic reaction of ATP hydrolysis is paired with an endergonic reaction in the pathway. The energy released from breaking a phosphate bond in ATP is used to phosphorylate another molecule and keep the reaction series moving forward.

ATP Powers Cellular Work

the first law of thermodynamics

Energy Changes in Cells and Matter

The first law of thermodynamics describes how energy changes form in the universe. The total amount of energy stays constant. Energy can move from one place to another or change into a different form, but it cannot be created or destroyed. These energy changes happen in everyday life. A light bulb changes electrical energy into light energy. A gas stove changes chemical energy in natural gas into heat energy. Plants also carry out a major energy transformation when they convert sunlight energy...

the second law of thermodynamics

Entropy and Spontaneous Change

Entropy helps predict whether a process will happen on its own. Entropy is a measure of randomness or disorder in a system. High entropy means high disorder and low energy. A student’s bedroom is a simple example. If no work is done, the room becomes messy over time. That messy state is highly disordered and has high entropy. To make the room clean again, energy must be added as the student puts things away. That organized state has low entropy. Processes that increase the entropy of the...

enthalpy within the cell

Cellular Enthalpy and Energy Changes

Cellular enthalpy describes how heat and energy change during chemical and physical processes. Enthalpy is written as H and is defined as the sum of a system’s internal energy, U, and the product of pressure and volume, PV. It is a state function, which means its value depends on the state of the system, not the path taken. Scientists cannot measure the enthalpy of a single substance directly. They can determine enthalpy changes, or ΔH, for a process instead. For reactions or changes that...

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Cell Energy Loss and Entropy

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Gibbs Free Energy and Reaction Work

Gibbs free energy describes the usable energy in a chemical reaction. It helps scientists compare how much energy different reactions release. This measurement is called Gibbs free energy, or G, after Josiah Willard Gibbs. The second law of thermodynamics explains why not all energy stays available for work. Some energy is lost in an unusable form, such as heat, and this loss increases entropy. Gibbs free energy is the energy left after that entropy loss is taken into account. Every chemical...

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Cell Reactions That Release or Store Energy

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the equilibrium binding constant and binding strength

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How Equilibrium Binding Constant Affects Binding

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Free Energy and Reaction Direction

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Cells Stay Out of Equilibrium

Cells stay out of chemical equilibrium by constantly using energy and moving materials in and out. Chemical reactions in metabolism are often reversible. They can go in both directions. In one direction, they release energy to the surroundings. In the reverse direction, they absorb energy. The same idea applies to reactions that build and break down cell molecules. Proteins, for example, can be broken into individual amino acids, and amino acids can be used to build proteins again. In a closed...

oxidation and reduction of organic molecules

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Electron Carriers in Cell Energy Transfer

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Enzyme Function, Cofactors, and Inhibitors

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Diffusion-Controlled Enzymes and Reaction Speed

Catalytically perfect enzymes are enzymes that speed up biochemical reactions at very high rates. The idea was first proposed by W. J. Albery and J. R. Knowles in 1976. These enzymes have catalytic efficiency values of about 10^8 to 10^9 M^-1 s^-1 and are also called diffusion-controlled enzymes because diffusion of the substrate into the active site is the only rate-limiting step. Examples of catalytically perfect enzymes include triose phosphate isomerase, fumarase, and superoxide dismutase.

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introduction-to-mechanisms-of-enzyme-catalysis

How Enzymes Change Shape to Catalyze

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Ligand Binding and Allosteric Effects

Ligand binding and linkage describe how one molecule can affect another when it binds to a protein. In this topic, the focus is on how binding at one site can influence activity at a different site on the same protein. This idea is important for understanding protein function in high school biology. It helps explain why some proteins respond more strongly after a ligand attaches. The transcript centers on the connection between ligand binding and linkage, which is a key concept in molecular...

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How Proteins Shift Shape Together

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atp energy storage and release

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...

atp and macromolecule synthesis

ATP in Building Cell Macromolecules

ATP helps cells build biological macromolecules. These organic compounds are mainly made of carbon atoms bonded to hydrogen, oxygen, nitrogen, and small amounts of other elements. The four major classes of biological macromolecules are carbohydrates, lipids, proteins, and nucleic acids. Most macromolecules start as small subunits called monomers. Cells join monomers with covalent bonds to make larger molecules called polymers. This building process needs energy, so cells depend on ATP, the...

coupled reactions

ATP powers many kinds of cellular work by coupling energy-releasing reactions to energy-requiring ones. Some reactions happen on their own and release energy. Others need an energy input to move forward. Cells link these reactions so important processes can still occur. Adenosine triphosphate, or ATP, stores energy that cells can use quickly. ATP hydrolysis is the breaking of ATP, and it releases energy. Cells often use that released energy to drive endergonic reactions, which are reactions...

key terms and concepts

See how ATP drives cellular work through energy coupling, from the sodium-potassium pump to glucose phosphorylation in glycolysis.

ATP Powers Cellular Work | JoVE K12

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

HS-PS1-5

Florida Department of Education

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SC.912.L.18

SC.912.L.18.10

Texas Essential Knowledge and Skills

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BIO.11

BIO.11.B

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P-PS3-3

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New York State Science Learning Standards

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HS-PS1-3

ATP Powers Cellular Work

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