Name: electron carriers in cellular respiration
Uploaded: 2019-03-11T09:21:11.000Z
Duration: 1 min 24 s
Channel: JoVE

K12 Standards

Virginia  Standards of Learning

HIgh School

Life Science

LS.4

LS.4.b

Electron Carriers

電子伝達体は 酸化還元反応を介した細胞の 抽出可能エネルギーの流れである 高エネルギー電子の周りを往復する化合物で 酸化と還元の状態を調整し これらの負の電気を帯びた粒子を 失ったり獲得したりします 例えば 主要な化合物の一つに ニコチンアミドアデニンジヌクレオチド(NAD)があり 片方のリボース環にはアデニン塩基が 他方には最初の炭素原子に結合した ニコチンアミドがあるので そういう名前が付いています 5番目の炭素位置で これら2つのヌクレオチドに 2つのリン酸基が結合します 代謝の際にNADは補酵素として 反応を触媒する酵素に結合し 酸化剤として作用し 1対の電子とともに 2つの水素原子を 糖などの反応物から取り除きます 次いで電子は 正電気を帯びた窒素に移動し 水素原子は反対側の炭素に結合して NADHを形成します 最後に 余分な水素陽子が細胞質に残り NADHはその電子を ミトコンドリア膜に移動させ そこで電子伝達系に入り 伝達体はさらに 酸化還元反応を経験します

電子キャリア

電子キャリアは、電子のシャトルと考えられています。これらの化合物は、簡単に電子を受け取ったり（つまり、還元されたり）、失ったり（つまり、酸化されたり）できます。したがって、細胞呼吸は電子の流れに依存していることから、電子キャリアはエネルギー産生に重要な役割を果たします。
 
 細胞呼吸の多くの段階を介して、グルコースは二酸化炭素と水に分解されます。電子キャリアは、これらの反応でグルコースが失った電子を拾い、一時的に電子を蓄えて、電子伝達系に受け渡します。
 
 そんな電子伝達体には、ビタミンB群由来のNAD+とFADがあります。NAD+とFAD2の還元型にあたる、NADHとFADH2は、細胞呼吸の初期段階（解糖、ピルビン酸酸化、クエン酸回路）で産生されます。
 
 還元型電子キャリアであるNADHとFADH2は、それぞれ電子伝達系の複合体Iと複合体IIに電子を運びます。この過程で、これらは酸化されNAD+とFADになります。
 
 電子伝達系には、フラボタンパク質、鉄硫黄クラスター、キノン、シトクロムなど他の電子キャリアもあります。これらの電子キャリアは、酵素の助けを借りて、最終的に電子を酸素分子へ渡します。電子キャリアは、電子を提供して酸化され、電子を受け取って還元されることで、交互に酸化型と還元型へ変化しています。
 
 電子キャリアは、電子の流れを制御することで、ATP産生を可能にしています。電子キャリアがなければ細胞の機能は止まるでしょう。

電子キャリアは、電子シャトルと考えることができます。これらの化合物は、電子を容易に受け入れる(すなわち、減少する)か、またはそれらを失う(すなわち、酸化される)ことができます。...

Education

JoVE Core

Biology

生物学

Cellular Processes

細胞プロセス

Cellular Respiration

細胞呼吸

KEY TERMS AND CONCEPTS

主要用語と概念

electron carriers in cellular respiration

Electron carriers help move electrons through cellular respiration. They act like shuttles that can accept electrons, which means they are reduced, or give electrons away, which means they are oxidized. This changing between oxidized and reduced forms is essential for energy production.

As glucose breaks down into carbon dioxide and water, it loses electrons at several stages. Electron carriers pick up those electrons and store them temporarily. They then release the electrons into the electron transport chain, where the cell can use them to make ATP.

NAD+ and FAD are two important electron carriers. Both come from B vitamins. Their reduced forms, NADH and FADH2, are made during glycolysis, pyruvate oxidation, and the citric acid cycle. NADH donates electrons to complex I of the electron transport chain, while FADH2 donates electrons to complex II.

Other electron carriers also work in the electron transport chain. These include flavoproteins, iron-sulfur clusters, quinones, and cytochromes. With help from enzymes, they pass electrons along until oxygen receives them. This controlled flow of electrons keeps ATP production going, and without it, the cell would stop working.

Electron Carriers in Cellular Respiration

electron-carriers-in-cellular-respiration

what is glycolysis?

Glycolysis: How Cells Break Down Glucose

Glycolysis is the first stage of cellular respiration and a key way cells break down glucose to make energy. Cellular respiration converts food energy from macromolecules into ATP, the cell’s main energy currency. Glycolysis also creates intermediate molecules that can feed into other pathways. In this pathway, one six-carbon sugar such as glucose is split into two three-carbon molecules, including pyruvate. The process produces a net gain of two ATP molecules, since four ATP are made and two...

energy-requiring steps of glycolysis

Glycolysis: Glucose Trapping and Splitting

Glycolysis begins in the cytosol, where glucose is prepared for use as energy. This process has two phases: an energy-requiring phase and an energy-releasing phase. The first phase changes glucose into a more reactive, unstable form before it can move into later steps. In the first step, glucose is phosphorylated, which means a phosphate group is added from ATP. This produces glucose 6-phosphate. The added phosphate is negatively charged, so it cannot cross the hydrophobic cell membrane. As a...

energy-releasing steps of glycolysis

Glycolysis: ATP and NADH Formation

Glycolysis produces ATP and NADH during its energy-releasing phase. These reactions are the last steps of glycolysis and convert glyceraldehyde-3-phosphate, or G3P, into pyruvate. The phase is often described as steps 6 to 10, and it happens twice because two 3-carbon sugars are made earlier in glycolysis. The sixth step begins with two linked events. G3P is oxidized, which means it loses hydrogen, and it is phosphorylated, which means a phosphate group is added. NAD+ acts as the electron...

pyruvate oxidation

How Pyruvate Becomes Acetyl CoA

Pyruvate is prepared for the next stage of cellular respiration inside the mitochondria. After glycolysis, the charged pyruvate molecules enter the mitochondria by active transport. There, they go through three enzymatic reactions so the energy stored in pyruvate can be used by the cell. First, pyruvate dehydrogenase removes the carboxyl group from pyruvate. This step releases carbon dioxide. Next, the stripped molecule is oxidized, and the electrons are picked up by NAD+ to make NADH. The...

the citric acid cycle

Citric Acid Cycle Energy and Products

The citric acid cycle is a key energy-making pathway in cells. It is also called the Krebs cycle or the TCA cycle. In eukaryotic cells, it takes place in the matrix of mitochondria. In prokaryotic cells, it occurs in the cytoplasm. The cycle starts with acetyl CoA, which enters the pathway after pyruvate oxidation. That earlier step makes two acetyl CoA molecules per glucose molecule. For that reason, the citric acid cycle runs twice for each glucose molecule. The pathway includes eight...

electron transport chains

ATP Production by the Electron Transport Chain

ATP production in the electron transport chain is the final stage of cellular respiration. This stage is part of oxidative phosphorylation, which has two steps: the electron transport chain and chemiosmosis. In eukaryotic cells, the electron transport chain sits in the inner mitochondrial membrane. Its main job is to build a proton gradient. That gradient is then used during chemiosmosis to make ATP. The process also regenerates the electron carriers NAD+ and FAD, which are needed again in...

chemiosmosis

ATP Production by Chemiosmosis

ATP production by chemiosmosis is part of oxidative phosphorylation, the efficient stage of cellular respiration that makes most of the cell’s ATP. Oxidative phosphorylation includes two linked processes: the electron transport chain and chemiosmosis. Together, they help generate adenosine triphosphate, or ATP, the main energy molecule used by cells. The electron transport chain is a series of protein complexes in the inner mitochondrial membrane. These complexes pass electrons through a set...

electron carriers

Electron carriers help move electrons through cellular respiration. They act like shuttles that can accept electrons, which means they are reduced, or give electrons away, which means they are oxidized. This changing between oxidized and reduced forms is essential for energy production. As glucose breaks down into carbon dioxide and water, it loses electrons at several stages. Electron carriers pick up those electrons and store them temporarily. They then release the electrons into the...

fermentation

Fermentation Pathways Without Oxygen

Fermentation is a metabolic pathway that lets cells make energy without oxygen. It begins after glucose is split into two pyruvate molecules during glycolysis. Glycolysis is the same first step used in aerobic respiration. When oxygen is unavailable, pyruvate does not enter aerobic respiration. Instead, cells convert pyruvate into other organic molecules through pathways that depend on the organism. A key purpose of fermentation is to regenerate NAD+ from NADH so glycolysis can keep running. <br...

dietary connections

How Food Becomes ATP

Food becomes ATP through connected steps in cellular respiration. Carbohydrates, proteins, and lipids all feed into these pathways. The body can use foods such as apples, cheese, and guacamole as sources of energy. Carbohydrate digestion starts with enzymes that break complex carbohydrates into simple sugars. Glucose can enter glycolysis directly. Fructose and galactose must first be converted into sugars that are intermediates of the glycolytic pathway. Proteins are digested into amino acids.

introduction to cellular respiration

Cellular Respiration: ATP Production Steps

Cellular respiration is the process cells use to turn energy from food into ATP. ATP, or adenosine triphosphate, stores energy in chemical bonds that can be released quickly when cells need it. Much of the energy released during respiration becomes heat, but some of it is captured to make ATP. This process depends on oxidation-reduction, or redox, reactions. In these reactions, oxidation means electron loss and reduction means electron gain. The electron carriers NAD+ and FAD, along with their...

products of the citric acid cycle

Citric Acid Cycle Output in Cellular Respiration

The citric acid cycle is a key stage of aerobic respiration in cells. It is also called the Krebs cycle or the tricarboxylic acid (TCA) cycle. Plants and animals use this oxygen-requiring pathway as part of cellular respiration. This cycle happens after glycolysis and pyruvate oxidation. Glycolysis makes two pyruvate molecules from each glucose molecule. During pyruvate oxidation, each pyruvate becomes acetyl-CoA, which is the input for the citric acid cycle. That means one glucose molecule...

outcomes of glycolysis

Glycolysis Products in Cellular Respiration

Glycolysis is the first step of cellular respiration and breaks glucose into smaller molecules. Cells use this process to pull energy from glucose over a series of chemical reactions. Cellular respiration can happen with oxygen or without oxygen. In both aerobic and anaerobic cellular respiration, glycolysis makes a net gain of two pyruvate molecules, two NADH molecules, and two ATP molecules. Four ATP molecules are produced, but two ATP molecules are used earlier in the pathway. Glycolysis...

atp yield

How Cellular Respiration Makes ATP

Cellular respiration makes ATP from glucose in several stages. The process usually produces 30 to 32 ATP per glucose molecule. Most of that ATP comes from oxidative phosphorylation and the electron transport chain, while 4 ATP are made earlier, with 2 from glycolysis and 2 from the citric acid cycle. The electron transport chain, or ETC, sits in the inner mitochondrial membrane. It has four main protein complexes and ATP synthase, the enzyme that makes ATP. NADH and FADH2 deliver electrons to...

key terms and concepts

Learn how NADH, FADH2, and other electron carriers move electrons through cellular respiration to support ATP production in high school biology.

Electron Carriers in Cellular Respiration | JoVE K12

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JoVE Core シリーズは、生物学の重要な概念を説明する 300 を超える簡潔でわかりやすいアニメーション ビデオ レッスンに加え、今日の研究室で行われる実際の研究実験を示す 150 以上の科学者の活動ビデオを通じて、生物学に命を吹き込みます。

Next Generation Science Standards

High School

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

From Molecules to Organisms: Structures and Processes

HS-LS1-7

Texas Essential Knowledge and Skills

BIO.11

BIO.11.A

myJoVE Corporation

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LS.4.a

Introduction to Cellular Respiration

Organisms harvest energy from food, but this energy cannot be directly used by cells. Cells convert the energy stored in nutrients into a more usable ...

What is Glycolysis?

Overview
Cells make energy by breaking down macromolecules. Cellular respiration is the biochemical process that converts &#34;food energy&#34; (from the ...

Energy-requiring Steps of Glycolysis

Glucose is the source of nearly all energy used by organisms. The first step of converting glucose into usable energy is called glycolysis. Glycolysis ...

Energy-releasing Steps of Glycolysis

Glycolysis is divided into two phases based on whether energy is utilized or released. While the first phase consumes ATP, the second phase produces ...

Outcomes of Glycolysis

Nearly all the energy used by cells comes from the bonds that make up complex organic compounds. These organic compounds are broken down into simpler ...

Pyruvate Oxidation

After glycolysis, the charged pyruvate molecules enter the mitochondria via active transport and undergo three enzymatic reactions. These reactions ensure ...

The Citric Acid Cycle

The citric acid cycle, also known as the Krebs cycle or TCA cycle, consists of several energy-generating reactions that yield one ATP molecule, three NADH ...

Products of the Citric Acid Cycle

The cells of most organisms&#8212;including plants and animals&#8212;obtain usable energy through aerobic respiration, the oxygen-requiring version of ...

Electron Transport Chains

The final stage of cellular respiration is oxidative phosphorylation that consists of two steps: the electron transport chain and chemiosmosis. The ...

Chemiosmosis

Oxidative phosphorylation is a highly efficient process that generates large amounts of adenosine triphosphate (ATP), the basic unit of energy that drives ...

Electron carriers can be thought of as electron shuttles. These compounds can easily accept electrons (i.e., be reduced) or lose them (i.e., be oxidized). ...

ATP Yield

Cellular respiration produces 30 - 32 ATP per glucose molecule. Although most of the ATP results from oxidative phosphorylation and the electron transport ...

Fermentation

Most eukaryotic organisms require oxygen to survive and function adequately. Such organisms produce large amounts of energy during aerobic respiration by ...

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Overview

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Free Energy

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Hydrolysis of ATP

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Phosphorylation

The addition or removal of phosphate groups from proteins is the most common chemical modification that regulates cellular processes. These modifications ...

The student will investigate and understand that there are chemical processes of energy transfer which are important for life. Key ideas include photosynthesis and cellular respiration support life processes.

Electron Carriers in Cellular Respiration

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