Name: how catalysts lower reaction barriers
Uploaded: 2019-03-11T09:21:09.000Z
Duration: 1 min 26 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Chemistry

Matter And Its Interactions

HS-PS1-4

Activation Energy

활성화 에너지는반응물 사이의 화학 반응을개시하는데 필요한 에너지이다에너지 근원은 종종 열에너지인데이는 분자가 더 빨리 움직이고서로 충돌하게 하여반응물의 결합을 부서지게 만든다그래서, 원래의 반응물은 반응이 일어나기 위해서자유 에너지가 필요하다이 커브의 오르막 부분으로 표시된이 에너지는 반응에 대한 활성화 에너지의 양이다전이 상태로 알려진 정점에서결합이 풀린 분자가 불안한 상태에 있다원자가 새로운 결합으로 재 부착될 때주위에 자유 에너지를 방출하는데이 반응의 내리막 부분으로 표시된다인간은 설탕과 지방 섭취하여 에너지를 얻지만열에너지가 이 분자들을 부수는데 이용된다면아주 많은 자유 에너지가 열로 방출되기 때문에아마도 세포 내의 단백질이 변성이 될 것이다대신에, 촉매라는 물질이구체적으로 첨가되어 신진대사의 속도를 규제하는데가속을 시켜준다이를테면, 생물학적 촉매인 효소는결합을 부수는데 필요한 활성화 에너지를 낮추어서세포에 피해 없이 합리적인 속도로 반응이일어나게 해준다

로빈슨, 피터 K. "효소: 원리와 생명공학 응용." Essays in Biochemistry 59 (2015년 11월 15일): 1–41. [<a href="https://doi.org/10.1042/bse0590001" target="__blank">소스</a>]

활성화 에너지

활성화 에너지(activation energy)는 화학 반응을 진행하기 위해 필요한 최소 에너지입니다. 활성화 에너지가 높을수록 반응 속도가 느려집니다. 그러나 반응에 열을 가하면 분자는 빠르게 움직이고 분자는 충돌할 가능성이 증가해 반응 속도가 빨라집니다. 결합의 충돌과 파괴는 반응이 에너지 장벽을 오르는 오르막 단계를 나타내며 전이상태(transition state)로 이어집니다. 전이상태에서 반응물(reactant)은 불안정하고 에너지가 높은 상태입니다. 새로운 화학 결합과 최종 생성물(product) 형성은 에너지 장벽을 내려가며 자유 에너지를 방출하는 내리막 단계입니다. 촉매는 활성화 에너지를 낮춰 반응 속도를 높입니다. 예를 들어 생물학에서 당과 지방을 대사하는 효소는 이 분자들의 분해가 일어나는 속도를 증가시키고 동시에 세포에서 단백질을 변성시키는 자유 에너지의 과잉 생산을 막습니다.
 
 <h4>촉매</h4>
 
 촉매는 활성화 에너지를 낮추어 반응 속도를 높이고, 그 과정에서 스스로 재생하는 물질입니다. 촉매는 반응이 일어날 수 있는 대체 경로(alternative pathway) 또는 작용을 제공하고 정반응(forward reaction)과 역반응(reverse reaction)을 가속합니다. 생물학에서 효소는 세포 대사의 반응에 필요한 활성화 에너지를 낮추기 때문에 촉매의 대표적인 예입니다.
 
 예를 들어, 인간은 에너지를 얻기 위해 당과 지방을 대사합니다. 이 물질대사가 열에너지만 사용한다면 열의 형태로 방출되는 자유 에너지는 세포의 단백질변성을 일으키고 비특이적으로 모든 반응을 촉매할 것입니다. 따라서 효소는 물질대사에서 분자를 분해하는 데 필수적인데, 효소가 기질(substrate)이라 불리는 특정 반응물에만 결합하여 반응물의 활성화 에너지를 낮추고 선택적으로 세포 반응을 촉매하기 때문입니다.

활성화 에너지는 화학 반응이 진행되는 데 필요한 최소한의 에너지입니다. 활성화 에너지가 높을수록 속도가 느려집니다 ...

Education

교육

JoVE Core

Biology

생물학

Cellular Processes

세포 과정

Metabolism

신진대사

KEY TERMS AND CONCEPTS

주요 용어 및 개념

how catalysts lower reaction barriers

Activation energy is the minimum energy a chemical reaction needs to keep going. When the activation energy is higher, the reaction usually happens more slowly. Adding heat can speed the reaction because molecules move faster and collide more often.

As reactants collide, bonds break and the reaction moves through an uphill phase. That step creates the transition state, which is an unstable, high-energy state of the reactants. After that, new bonds form, products appear, and free energy is released in the downhill phase.

Catalysts speed up reactions by lowering the activation energy. A catalyst is a substance that takes part in the reaction pathway and then regenerates itself. It offers an alternate mechanism and speeds up both the forward and reverse reactions.

In biology, enzymes are catalysts that help cells control metabolism. They help break down sugar and fat for energy, and they do it without releasing too much free energy as heat. That matters because excess heat could denature proteins in the cell.

Enzymes are also selective. They bind only to specific reactants called substrates and lower the activation energy for those reactions. Thermal energy alone would not be as selective and could drive many reactions at once, but enzymes support specific cellular reactions instead.

How Catalysts Lower Reaction Barriers

what is metabolism?

Metabolism, Energy, and Cell Reactions

Metabolism is the set of chemical reactions that happen in a cell. It includes anabolism, which builds molecules, and catabolism, which breaks them down. These reactions help cells manage energy and keep life processes running. Cells use metabolism to turn food into energy, make cell parts, and remove waste products. Food stores potential energy in the bonds between atoms. Catabolic pathways break large food molecules into smaller ones and release that energy. Anabolic pathways use that energy...

first law of thermodynamics

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second law of thermodynamics

Entropy in Food Web Energy Flow

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kinetic energy

Motion as a Source of Energy

Kinetic energy is the energy of motion. It appears when an object is moving and can do work or cause change. A waterfall is one clear example. Water behind a dam has potential energy, but when it rushes downward, that moving water has kinetic energy. When the water reaches the bottom and stops moving, its energy can become potential energy again. Kinetic energy also shows up in living systems. Plants absorb light particles, called photons, which move very fast and help create chemical energy...

potential energy

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Stored energy in motion and bonds is called potential energy. It depends on the structure of an object or the position of matter in space. Raising a kettlebell changes its location and increases its potential energy. A stretched rubber band also stores potential energy, which can later change into kinetic energy. Chemical bonds between atoms hold another form of stored energy called chemical energy. These bonds involve attractive forces, and that energy can change into other forms during a...

free energy

Gibbs Free Energy in Chemical Reactions

Gibbs free energy is a measure of useful energy that can be taken from a chemical reaction to do work. It is written as G and named for scientist Gibbs, who discovered it. This energy is what remains after entropy is considered. A reaction can either take in energy or release it. Reactions that absorb energy are called endergonic reactions. Reactions that release energy are called exergonic reactions. The direction of energy flow helps show which type of reaction is happening. Plants carry...

activation energy

Activation energy is the minimum energy a chemical reaction needs to keep going. When the activation energy is higher, the reaction usually happens more slowly. Adding heat can speed the reaction because molecules move faster and collide more often. As reactants collide, bonds break and the reaction moves through an uphill phase. That step creates the transition state, which is an unstable, high-energy state of the reactants. After that, new bonds form, products appear, and free energy is...

hydrolysis of atp

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phosphorylation

Phosphorylation and Protein Control

Phosphorylation helps control how proteins work in cells. It is the addition or removal of phosphate groups, and it is the most common chemical change that regulates cellular processes. These changes can alter a protein’s structure, activity, stability, location inside the cell, and interactions with other proteins. During phosphorylation, protein kinases move the terminal phosphate group from ATP to a specific amino acid side chain on a target protein. The amino acids most often...

induced-fit model

How Enzymes Adjust to Their Substrates

Enzymes speed up many chemical reactions in cells. They are biological catalysts, so they increase reaction speed without being consumed or permanently changed. They do this by lowering the activation energy needed to turn reactants into products. Enzymes are proteins that usually work by binding to a substrate, which is the reactant molecule they act on. They show substrate specificity, meaning they bind only certain substrates. This specificity depends mainly on the shape and chemical...

enzyme kinetics

Substrate Effects on Enzyme Rates

Enzyme kinetics examines how enzymes change the rate of a reaction. Enzymes speed reactions by lowering the activation energy of the reactants. The reaction rate is the speed at which an enzyme turns reactants into products, and it can be affected by several factors, including the number of available reactants. Scientists often study enzyme kinetics in a test tube with a fixed amount of enzyme. When more substrate, or reactant, is added, the reaction rate increases because the enzyme can make...

enzyme inhibition

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feedback inhibition

How Cells Control Product Buildup

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allosteric regulation

Allosteric Control of Enzyme Speed

Allosteric control changes enzyme speed when a molecule binds to a site other than the active site. That alternate binding spot is called an allosteric site. An enzyme can have more than one allosteric site. This type of control can raise or lower enzyme activity. Many enzymes with allosteric control are metabolic enzymes. They help with the breakdown or the building of specific molecules in cells. In allosteric inhibition, the effector molecule causes a shape change that lowers the enzyme's...

cofactors and coenzymes

Enzyme Helpers: Metals, Vitamins, and More

Enzyme helpers are needed for many enzymes to work properly. These helpers fall into two groups: cofactors and coenzymes. Cofactors are metallic ions, while coenzymes are non-protein organic molecules. Both can be tightly bound to an enzyme or attach only when the substrate binds. Cofactors are common in mature proteins, appearing in about 30% of them. They are often added as the enzyme folds and help with catalytic activity. Magnesium is one important cofactor, and it is needed by more than...

key terms and concepts

Learn how heat, transition states, catalysts, and enzymes affect reaction speed. See how lowering activation energy helps cells break down sugar and fat.

How Catalysts Lower Reaction Barriers | JoVE K12

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JoVE Core 시리즈는 생물학의 주요 개념을 설명하는 300개가 넘는 간결하고 이해하기 쉬운 애니메이션 비디오 강의와 오늘날 실험실에서 수행된 실제 연구 실험을 보여주는 150개가 넘는 과학자 활동 비디오를 통해 생물학에 활기를 불어 넣습니다.

Tennessee Academic Standards

Energy

CHEM1.PS3.3

Minnesota Academic Standards in Science

9-12

3.1.1 9C.2.2.1.1

Alabama Course of Study Science

Physical Science

9-12.PS.1.1

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How Catalysts Lower Reaction Barriers

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