Name: cellular enthalpy and energy changes
Uploaded: 2023-04-30T10:40:59.000Z
Duration: 1 min 18 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Biology

BIO.11

BIO.11.A

Enthalpy within the Cell

내부 에너지 또는 E는 화학 결합에 포함된 에너지 및 입자의 무작위 운동과 같이 시스템 내에 포함된 에너지입니다. 시스템과 그 주변 환경은 시스템 간에 에너지를 전달할 수 있습니다.
시스템의 내부 에너지 변화 델타 E는 시스템으로 전달되는 총 열인 q와 시스템에서 수행된 총 작업인 w의 합과 같습니다.
대부분의 생화학 반응에서는 어떤 작업도 수행되지 않으므로 내부 에너지의 변화는 엔탈피라고 하는 다른 열역학적 기능과 동일합니다.
시스템 또는 ∆H의 엔탈피 변화는 주변 엔탈피의 동일하고 반대되는 변화를 동반합니다.
발열 과정은 시스템이 주변으로 열을 방출하고 음의 엔탈피로 표시되는 경우입니다. 흡열 과정은 시스템이 양의 엔탈피로 표시되는 열을 얻을 때입니다.
살아있는 세포는 열역학 제1법칙에 따라 발열 및 흡열 과정을 통해 주변 환경과 물질과 에너지를 교환하는 열린 시스템입니다.

세포 내 엔탈피

엔탈피(H)는 화학적 및 물리적 과정의 열역학을 설명하는 데 사용됩니다. 엔탈피는 시스템의 내부 에너지(U)와 압력(P) 및 부피(V)의 수학적 곱의 합으로 정의됩니다.

H = U + PV

엔탈피도 상태함수입니다. 특정 물질의 엔탈피 값은 직접 측정할 수 없습니다. 화학적 또는 물리적 과정에 대한 엔탈피 변화만 결정할 수 있습니다. 일정한 압력(많은 화학적 및 물리적 변화에 대한 일반적인 조건)에서 발생하는 공정의 경우 엔탈피 변화(ΔH)는 다음과 같습니다.

ΔH = ΔU + PΔV

분젠 버너를 작동할 때 방출되는 열은 발생하는 메탄 연소 반응의 엔탈피 변화와 동일합니다. 왜냐하면 이 반응은 본질적으로 일정한 대기압에서 발생하기 때문입니다. 엔탈피 변화의 음수 값(ΔH < 0)은 발열 반응을 나타냅니다. 양수 값인 ΔH > 0은 흡열 반응을 나타냅니다.

ΔH와 델타 G(ΔG)라고 불리는 자유 에너지의 변화는 Gibbs Helmholtz 방정식으로 알려진 다음 방정식과 관련됩니다.  

ΔG = ΔH − TΔS

일반적으로 생물학적 시스템에서 표준 pH, 온도, 압력 조건은 각각 pH 7.0, 섭씨 25도, 100킬로파스칼(1bar)입니다. 세포 조건은 이러한 표준 조건과 상당히 다르므로, 생물학적 반응에 대한 표준 계산된 ∆G 값은 세포 내에서 다를 수 있습니다.

이 텍스트는 Openstax, Biology 2e에서 가져온 것입니다 <a href="https://openstax.org/books/biology-2e/pages/6-3-the-laws-of-thermodynamics">Section 6.3: The Laws of Thermodynamics</a> 그리고 Openstax, Chemistry 2e, <a href="https://neuron4.jove.com/publish/util/translations.php?id=12545&language=Korean">Section 5.3: Enthalpy.</a>

엔탈피(H)는 화학적 및 물리적 과정의 열역학을 설명하는 데 사용됩니다. 엔탈피는 시스템의 내부 에너지의 합으로 정의됩니다 ...

Education

교육

JoVE Core

Cell Biology

세포생물학

Unit 1

제1단원

Energy and Catalysis

에너지 및 촉매

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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 occur at constant pressure, which is common in many chemical and physical processes, ΔH equals ΔU + PΔV.

A simple example is the heat released when a Bunsen burner burns methane. That heat is equal to the enthalpy change of the combustion reaction because the reaction happens at essentially constant atmospheric pressure. A negative ΔH means the reaction is exothermic, while a positive ΔH means it is endothermic.

Enthalpy also connects to free energy through the Gibbs-Helmholtz equation, ΔG = ΔH − TΔS. In biology, standard conditions are usually pH 7.0, 25 degrees Celsius, and 100 kilopascals, or 1 bar. Cellular conditions often differ from these standards, so standard calculated ΔG values for biological reactions can change inside the cell.

Cellular Enthalpy and Energy Changes

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 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...

entropy within the cell

Cell Energy Loss and Entropy

Cell energy loss and entropy explain why living things need constant energy input. Cells obtain energy, transform it, and use it to do work, but these transfers are never completely efficient. In each transfer, some energy is lost in a form that cannot be used. In many cases, that lost energy is heat energy.

an introduction to free energy

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...

endergonic and exergonic reactions in the cell

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Cell Reactions That Release or Store Energy

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the equilibrium binding constant and binding strength

the-equilibrium-binding-constant-and-binding-strength

How Equilibrium Binding Constant Affects Binding

The equilibrium binding constant describes how strongly two molecules bind at equilibrium. It is a useful way to compare binding strength in molecular interactions. This topic focuses on how binding is measured and what the equilibrium binding constant means. A higher value indicates stronger binding, while a lower value indicates weaker binding. Understanding this constant helps explain how tightly molecules stay together under equilibrium conditions. The page also connects the binding...

free energy and equilibrium

Free Energy and Reaction Direction

Free energy and reaction direction are linked in chemical equilibrium. A free energy change, ΔG, shows the driving force for a process. When ΔG is negative, the process is driven forward. When ΔG is positive, the reverse direction is favored. When ΔG is zero, the forward and reverse driving forces are equal, and the system is at equilibrium. The reaction quotient, Q, helps show how close a system is to equilibrium. Q is the numerical value of the mass action expression for the system. It can...

non-equilibrium in the cell

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

oxidation-and-reduction-of-organic-molecules

Electron Carriers in Cell Energy Transfer

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introduction to enzymes

Enzyme Function, Cofactors, and Inhibitors

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enzymes and activation energy

How Enzymes Lower Reaction Energy

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Graphing Enzyme Kinetics Data

Enzyme kinetics uses graphs to show how fast a biochemical reaction happens. Scientists measure the initial reaction rate, or velocity (Vo), at different substrate concentrations ([S]). They may also run trials with inhibitors or other molecules that change the reaction rate. The results are often plotted as Vo against [S]. For many single-substrate reactions, the data fits the Michaelis-Menten equation. This equation, named after Leonor Michaelis and Maud Menten, helps estimate the maximum...

turnover number and catalytic efficiency

How Fast Enzymes Work in Digestion

Enzymes can work at very different speeds, and their turnover number shows how fast they convert substrate molecules into products. Turnover number is the maximum number of substrate molecules an enzyme can transform per unit time. For most enzymes, this value is between 1 and 1000 molecules per second. Some enzymes are especially fast. Catalase has the highest known turnover number and can convert up to 2.8×10^6 molecules of hydrogen peroxide into water and oxygen each second. Lysozyme has...

catalytically perfect enzymes

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.

introduction to mechanisms of enzyme catalysis

introduction-to-mechanisms-of-enzyme-catalysis

How Enzymes Change Shape to Catalyze

Enzyme catalysis depends on how enzymes bind substrates and how the active site responds during the reaction. Scientists once described this process with a simple lock-and-key model, where the enzyme and substrate fit together in one instant. Research now supports induced fit, a more dynamic model in which binding causes a small change in the enzyme’s shape. That shift helps create an ideal match between the enzyme and the substrate’s transition state, which improves catalysis. The active site...

ligand binding and linkage

Ligand Binding and Allosteric Effects

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cooperative allosteric transitions

How Proteins Shift Shape Together

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ribozymes

Catalytic RNA: Ribozymes in Action

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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...

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ATP Powers Cellular Work

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key terms and concepts

Explore enthalpy, ΔH, and Gibbs free energy in cells. Learn how constant pressure, exothermic and endothermic reactions, and cellular conditions affect energy change.

Cellular Enthalpy and Energy Changes | 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.

Enthalpy (H) is used to describe the thermodynamics of chemical and physical processes. Enthalpy is defined as the sum of a system&#39;s internal energy ...

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What is Glycolysis?

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Energy-requiring Steps of Glycolysis

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Energy-releasing Steps of Glycolysis

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Outcomes of Glycolysis

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Pyruvate Oxidation

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The Citric Acid Cycle

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Products of the Citric Acid Cycle

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Electron Transport Chains

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Chemiosmosis

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Electron Carriers

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ATP Yield

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Fermentation

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Dietary Connections

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Explain how matter is conserved and energy is transferred during photosynthesis and cellular respiration using models, including the chemical equations for these processes.

Introduction to Enzymes

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Enzymes and Activation Energy

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Introduction to Enzyme Kinetics

Enzyme kinetics studies the rates of biochemical reactions. Scientists monitor the reaction rates for a particular enzymatic reaction at various substrate ...

Introduction to Mechanisms of Enzyme Catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple &#34;lock-and-key&#34; fashion. This model stated that the enzyme ...

Ligand Binding and Linkage

Cooperative Allosteric Transitions

Ribozymes

ATP Energy Storage and Release

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ATP and Macromolecule Synthesis

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Coupled Reactions

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Overview of Metabolism

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Investigate and explain the role of enzymes in facilitating cellular processes.

BIO.11.B

Science concepts--biological structures, functions, and processes. The student knows the significance of matter cycling, energy flow, and enzymes in living organisms. The student is expected to:

Cellular Enthalpy and Energy Changes

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