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

- [Istruttore] I trasportatori
di elettroni sono composti

che muovono gli elettroni
ad alta carica energetica,

la fonte primaria di
energia delle cellule,

tramite reazioni di
ossidoriduzione, stati coordinati

di ossidazione e riduzione,
che perdono e guadagnano

rispettivamente queste
particelle a carica negativa.

Per esempio, un composto
principale è la nicotinammide

adenina dinucleotide, o
NAD, chiamata così a perché

un anello di ribosi ha
una base di adenina,

mentre l'altro ha una
nicotinammide attaccato

al primo atomo di carbonio.

Nella posizione del
quinto atomo di carbonio,

questi due nucleotidi si
uniscono a due gruppi fosfati.

Durante il metabolismo,
il NAD, come coenzima,

si lega a un enzima che
catalizza le reazioni

e agisce da agente ossidante,
eliminando due atomi

di idrogeno, insieme
a un paio di elettroni

da un reagente, come uno zucchero.

Gli elettroni vengono quindi trasferiti

al nitrogeno dalla carica positiva

e un atomo di idrogeno viene collegato

al carbonio opposto, formando il NADH.

Alla fine, i protoni di
idrogeno extra vengono lasciati

nel citoplasma e il NADH
trasporta gli elettroni

alla membrana mitocondriale,

dove entrano nella catena di
trasporto degli elettroni,

mentre i trasportatori
continuano con l'ossidoriduzione.

portatori di elettroni

I trasportatori elettronici (o vettori) possono essere considerati come navette elettroniche. Questi composti possono facilmente accettare elettroni (cioè essere ridotti) o perderli (cioè, essere ossidati). Essi, quindi, svolgono un ruolo essenziale nella produzione di energia perché la respirazione cellulare è subordinata al flusso di elettroni.

Nel corso delle molte fasi della respirazione cellulare, il glucosio si rompe in anidride carbonica e acqua. I trasportatori di elettroni raccolgono gli elettroni persi dal glucosio in queste reazioni, immagazzinano temporaneamente gli elettroni e li inseriscono nella catena di trasporto degli elettroni.

Due di questi vettori elettronici sonoNAD e FAD, entrambi derivati da vitamine del gruppo B. Le forme ridotte diNAD e FAD, NADH e FADH2, vengono prodotte rispettivamente durante le fasi precedenti della respirazione cellulare (glicolisi, ossidazione del piruvato e ciclo dell'acido citrico).

I vettori di elettroni ridotti NADH e FADH2 passano gli elettroni nei complessi I e II della catena di trasporto degli elettroni, rispettivamente. Nel processo, sono ossidati per formareNAD e FAD.

Ulteriori vettori elettronici nella catena di trasporto degli elettroni sono flavoproteine, ammassi di ferro-zolfo, quinoni e citocromi. Con l'aiuto degli enzimi, questi vettori di elettroni alla fine trasferiscono gli elettroni in molecole di ossigeno. I vettori elettronici si ossidano quando donano elettroni e si riducono man mano che li accettano, e quindi si alternano tra le loro forme ossidiate e ridotte.

I vettori elettronici forniscono un flusso controllato di elettroni che consente la produzione di ATP. Senza di loro, la cellula cesserebbe di funzionare.

Portatori di elettroni

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). ...

Education

Didattica

JoVE Core

Biology

Biologia

Cellular Processes

Processi cellulari

Cellular Respiration

Respirazione cellulare

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

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 Biologia illustra i concetti chiave della biologia grazie a oltre 300 video-lezioni animate, concise e di facile comprensione. Inoltre, negli oltre 150 video di "scienziati in azione", i concetti scientifici vengono applicati e dimostrati da ricercatori attraverso esperimenti in laboratorio.

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

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LS.4.a

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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

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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

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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 ...

ATP Yield

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Fermentation

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Electron Carriers in Cellular Respiration

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