Name: electron carriers in cellular energy
Uploaded: 2025-05-22T09:05:36.000Z
Duration: 1 min 29 s
Channel: JoVE

K12 Standards

Florida Department of Education

High School

Life Science

SC.912.L.18

SC.912.L.18.8

Role of Reduced Coenzymes NADH and FADH&#8322;

Nicotinamid-Adenin-Dinukleotid oder NAD+ und Flavin-Adenin-Dinukleotid oder FAD sind die beiden wichtigen Coenzyme, die als Elektronenträger in verschiedenen biochemischen Reaktionen wirken.
Während einer Oxidationsreaktion absorbieren diese Coenzyme Elektronen und werden zu NADH und FADH2 reduziert.
Während der Reduktion setzen die reduzierten Coenzyme dann die Elektronen frei und wandeln sich wieder in ihre oxidierte Form um.
In eukaryotischen Zellen sind die Glykolyse und der TCA-Zyklus zwei Hauptquellen für reduzierte Coenzyme.
Im Zytosol oxidiert die Glykolyse Glukose zu Pyruvat, wodurch NAD+ zu NADH reduziert wird.
In den Mitochondrien produziert der TCA-Zyklus drei Moleküle NADH und ein Molekül FADH2.
Das im Zytosol produzierte NADH kann jedoch nicht direkt in die Mitochondrien gelangen. Daher übertragen zwei Trägerwege – das Malat-Aspartat-Shuttle und das Glycerinphosphat-Shuttle – die Elektronen auf NAD+ oder FAD, die in den Mitochondrien vorhanden sind.
Schließlich geben die reduzierten Coenzyme ihre Elektronen an die Elektronentransportkette ab, um eine Protonenantriebskraft für die ATP-Produktion zu erzeugen.

rolle der reduzierten coenzyme nadh und fadh₂

Die beim Abbau der chemischen Bindungen in Nährstoffen freigesetzte Energie kann entweder durch die Reduktion von Elektronenträgern oder in den Bindungen von Adenosintriphosphat (ATP) gespeichert werden. In lebenden Systemen fungiert eine kleine Klasse von Verbindungen als mobile Elektronenträger, Moleküle, die hochenergetische Elektronen binden und auf Pfaden zwischen Verbindungen transportieren. Die wichtigsten betrachteten Elektronenträger stammen aus der Gruppe der B-Vitamine und sind Derivate von Nukleotiden; Es handelt sich um Nicotinamidadenindinukleotid, Nikotinadenindinukleotidphosphat und Flavinadenindinukleotid. Diese Verbindungen können leicht reduziert oder oxidiert werden.

Nicotinamidadenindinukleotid (NAD+/NADH) ist der am häufigsten im Katabolismus verwendete mobile Elektronenträger. NAD+ ist die oxidierte Form des Moleküls; NADH ist die reduzierte Form des Moleküls. Nikotin-Adenin-Dinukleotidphosphat (NADP+), die oxidierte Form einer NAD+-Variante, die eine zusätzliche Phosphatgruppe enthält, ist ein weiterer wichtiger Elektronenträger; es bildet NADPH, wenn es reduziert wird. Die oxidierte Form von Flavinadenindinukleotid ist FAD und seine reduzierte Form ist FADH2. Sowohl NAD+/NADH als auch FAD/FADH2 werden in großem Umfang bei der Energiegewinnung aus Zuckern während des Katabolismus in Chemoheterotrophen verwendet, während NADP+/NADPH eine wichtige Rolle bei anabolen Reaktionen und der Photosynthese spielt. Zusammengenommen werden FADH2, NADH und NADPH aufgrund ihrer Fähigkeit, Elektronen für verschiedene chemische Reaktionen abzugeben, oft als reduzierend bezeichnet.

Dieser Text ist adaptiert von <a href="https://openstax.org/books/microbiology/pages/8-1-energy-matter-and-enzymes">Openstax, Microbiology, Section 8.1: Energy, Matter and Enzymes</a>

Rolle der reduzierten Coenzyme NADH und FADH₂

Die Energie, die durch den Abbau der chemischen Bindungen innerhalb von Nährstoffen freigesetzt wird, kann entweder durch die Reduktion von Elektronenträgern oder in der ...

Education

Lehre

JoVE Core

Cell Biology

Zellbiologie

Unit 1

Einheit 1

Introduction to Metabolism

Einführung in den Stoffwechsel

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

electron carriers in cellular energy

Electron carriers help store and move energy during nutrient breakdown. Cells can save released energy by reducing these carriers or by making ATP, the cell’s main energy molecule. These mobile electron carriers bind high-energy electrons and shuttle them between compounds in metabolic pathways.

The main carriers discussed here come from the B vitamin group and are nucleotide derivatives. They include nicotinamide adenine dinucleotide, nicotinamide adenine dinucleotide phosphate, and flavin adenine dinucleotide. These compounds can switch easily between oxidized and reduced forms.

NAD+ is the oxidized form of nicotinamide adenine dinucleotide, and NADH is its reduced form. NAD+ is the most common mobile electron carrier used in catabolism, the breakdown of molecules for energy. NADP+ is a related carrier with an extra phosphate group, and its reduced form is NADPH. FAD is the oxidized form of flavin adenine dinucleotide, and FADH2 is its reduced form.

NAD+/NADH and FAD/FADH2 are used widely in energy extraction from sugars during catabolism in chemoheterotrophs. NADP+/NADPH has a different main role. It is important in anabolic reactions and in photosynthesis. FADH2, NADH, and NADPH are often called reducing power because they can donate electrons to other chemical reactions.

Electron Carriers in Cellular Energy

overview of metabolism

Metabolism in Plants, Animals, and Microbes

Metabolism is the set of chemical reactions that keep living cells working. These reactions are linked through many pathways. Together, they support the normal function of cells in plants, animals, and microbes. In plants, sunlight is the main energy source. Chlorophyll pigments in the leaves absorb this light. The plant then uses that energy for photosynthesis. During photosynthesis, water is oxidized to oxygen and carbon dioxide is reduced to glucose. Glucose then serves as a starting...

carbohydrate metabolism

Carbohydrates, Digestion, and Blood Sugar

Carbohydrates are an important source of energy and a key part of human nutrition. They are made of carbon, hydrogen, and oxygen. One gram of carbohydrate provides four kilo-calories of energy, so carbohydrates are the body’s most efficient instant fuel. Starch makes up about 60% of the carbohydrates people eat. It is broken down by amylase enzymes, but amylase cannot work in the stomach’s acidic environment. That is why starch digestion happens in the mouth and the small intestine. Simple...

glycolysis: preparatory phase

Glycolysis: Energy Investment Steps

Glycolysis begins with energy investment steps in the cytoplasm of both prokaryotic and eukaryotic cells. It is the first step in cellular metabolism, which is the complete breakdown of glucose to extract energy. In heterotrophic cells, glucose enters by secondary active transport or through GLUT proteins, which are glucose transporter proteins that help glucose diffuse into the cell. The pathway starts with one six-carbon, ring-shaped glucose molecule and ends with two three-carbon molecules...

glycolysis: pay-off phase

Glycolysis: ATP and NADH Output

The pay-off phase of glycolysis turns the two three-carbon sugar molecules into ATP, NADH, and pyruvate. By this stage, the cell has already spent two ATP molecules. The remaining reactions recover that investment and add two more ATP molecules and two high-energy NADH molecules. The sixth step oxidizes glyceraldehyde 3-phosphate, a three-carbon sugar made earlier in glycolysis. High-energy electrons are transferred to NAD+, which becomes NADH. A second phosphate group is then added to form...

fates of pyruvate

Pyruvate Pathways in Fermentation

Pyruvate is a key product of glycolysis and can follow different pathways depending on oxygen availability. During glycolysis, glucose is oxidized to pyruvate, NAD+ is reduced to NADH, and two ATP are made by substrate-level phosphorylation. In aerobic organisms, pyruvate then enters the citric acid cycle, which helps produce the reduced coenzymes NADH and FADH2. These coenzymes are later oxidized in the electron transport chain to make ATP and regenerate NAD+ and FAD. When oxygen is absent,...

role of reduced coenzymes nadh and fadh&#8322;

Electron carriers help store and move energy during nutrient breakdown. Cells can save released energy by reducing these carriers or by making ATP, the cell’s main energy molecule. These mobile electron carriers bind high-energy electrons and shuttle them between compounds in metabolic pathways. The main carriers discussed here come from the B vitamin group and are nucleotide derivatives. They include nicotinamide adenine dinucleotide, nicotinamide adenine dinucleotide phosphate, and flavin...

overview of nitrogen metabolism

Nitrogen Cycle in Soil and Plants

Nitrogen moves through soil, plants, animals, and microbes in a cycle that keeps this macronutrient available for life. It is a major part of proteins and nucleic acids, so cells need it to build both amino acids and nucleotides. In nature, nitrogen is recycled from organic compounds and stored in several forms, including ammonia, ammonium ions, nitrate, nitrite, and nitrogen gas. Many of the key steps in this cycle are carried out only by prokaryotes. The largest nitrogen pool in terrestrial...

overview of fatty acid metabolism

Fatty Acids: Energy, Membranes, and Cholesterol

Fatty acids help cells store and use energy, and they also support important cell structures. Lipids are nonpolar and hydrophobic, so they do not mix well with water. Major lipid types include fats and oils, waxes, phospholipids, and steroids. Cells break down fatty acids by beta-oxidation. This process happens in the matrix of the mitochondria and cuts fatty acid chains into two-carbon acetyl groups. CoA picks up these groups to form acetyl CoA, which then enters the citric acid cycle. Extra...

sugars as energy storage molecules

Glucose Storage in Plants and Animals

Glucose storage in plants and animals helps cells manage energy for metabolism. Sugar is a simple carbohydrate, and cells use it because a lot of energy is stored in its bonds. Consumed carbohydrates often come from photosynthesizing organisms, especially plants. Plants make glucose during photosynthesis by using sunlight to convert carbon dioxide into sugar molecules. Because this builds a larger, energy-storing molecule, the process needs an energy input. Glucose can then be stored for later...

fats as energy storage molecules

How Triglycerides Fuel ATP Production

Triglycerides store long-term energy in fats. A triglyceride is built from glycerol and three fatty acids. When the body needs energy, these molecules are broken down first. This breakdown is called lipolysis, and it happens in the cytoplasm by hydrolysis. Lipolysis splits triglycerides into fatty acids and glycerol. The glycerol then enters glycolysis as DHAP, which connects fat breakdown to the cell’s main energy pathway. The fatty acids are then oxidized by beta-oxidation into acetyl-CoA.

regulation of metabolism

How Cells Control Metabolic Enzymes

Cells control metabolic enzymes to match changing needs and conditions. Different cells use different enzymes and energy levels, and those needs can also change within the same cell over time. Stomach cells, fat storage cells, skin cells, blood cells, and nerve cells do not all need the same metabolic activity. A digestive cell also works harder soon after a meal than it does many hours later. As cell needs change, the amount and activity of enzymes change too. Enzymes lower activation energy,...

positive and negative feedback loops

Homeostasis and Body Feedback Control

Homeostasis keeps body conditions in a steady range through feedback control. Animal organs and organ systems constantly adjust to internal and external changes. This balance is called a dynamic equilibrium because the body keeps adapting while still staying within specific ranges. The goal of homeostasis is to stay near a set point, which is the value the body tries to maintain. A change in the internal or external environment is a stimulus. A receptor detects that change and sends a signal...

key terms and concepts

Learn how NADH, FADH2, and NADPH carry electrons, store energy, and support catabolism, anabolism, and photosynthesis in cells.

Electron Carriers in Cellular Energy | JoVE K12

cell biology

JoVE Core Zellbiologie veranschaulicht komplexe zelluläre Prozesse in leicht verständlichen und dennoch umfassenden animierten Videolektionen. Diese Sammlung konzentriert sich auf die wesentlichen Bestandteile und Funktionen von Zellen, einschließlich Organellen und Membranen, Zelltransport und Zellenergie. Ergänzt wird sie durch Videos von Wissenschaftlern in Aktion, die die Anwendung der Zellbiologie in realen Forschungsexperimenten demonstrieren.

Macromolecules

Biomolecules
Organisms contain a wide variety of organic molecules with numerous functions which depend on the chemical structures and properties of these ...

Polymers

What are Lipids?

Lipids function as structural components of cellular membranes, in addition to acting as energy reservoirs and signaling molecules. They are thus crucial ...

Structure of Lipids

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Lipid-derived Compounds in the Human Body

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Amino acids

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Peptide Bonds

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What are Proteins?

Protein and Protein Structures

Protein Organization

Globular Proteins

In organisms, proteins are the most abundant macromolecules. They act as the building blocks of life and play various crucial roles in the body. Proteins ...

Fibrous Proteins

Fibrous proteins are either long and narrow proteins or assemble to form long and thin structures. They contain repetitive units and usually consist of ...

Protein Denaturation

The function of proteins depends on their native three-dimensional structure, which is dictated by the amino acid sequence of the specific protein. ...

Role of Proteins in the Human Body

Proteins are the building block of life. They are also&#160; the most abundant macromolecules with as many diverse roles in the body. They are part of ...

Mechanical Protein Function

Structural Protein Function

Introduction to Carbohydrates

Carbohydrates, proteins, and fats are the primary macronutrients in the human diet. However, carbohydrates are the most favored source of energy in the ...

Chemistry of Carbohydrates

Sugars as Energy Storage Molecules

Nucleic Acids and Nucleotides

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Nucleic Acid Structure

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The DNA Helix

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RNA Structure

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Types of RNA

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Noncovalent Attractions in Biomolecules

Describe the basic molecular structures and primary functions of the four major categories of biological macromolecules.

SC.912.L.18.1

Cellulose and Pectic Polysaccharides

&#160;Every plant cell has a cell wall that protects the cell, provides structural support, and gives the cell shape. Cellulose, the main structural ...

Membrane Carbohydrates

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Describe the important structural characteristics of monosaccharides, disaccharides, and polysaccharides and explain the functions of carbohydrates in living things.

SC.912.L.18.2

Overview of Fatty Acid Metabolism

Lipids also are sources of energy that power cellular processes. Like carbohydrates, lipids are composed of carbon, hydrogen, and oxygen, but these atoms ...

What are Membranes?

A cell&#39;s plasma membrane demarcates the cell&#39;s borders and determines the nature of its interaction with the environment. Cells exclude certain ...

Membrane Fluidity

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Fluid Mosaic Model

Scientists identified the plasma membrane in the 1890s and its principal chemical components (lipids and proteins) by 1915. The model for plasma membrane ...

Membrane Lipids

Lipids are an essential component of all biological membranes. The average lipid content in mammalian membranes is 50%, though it can be as low as 20% in ...

Asymmetric Lipid Bilayer

Biological membranes show uneven distribution of different types of lipids in the inner and outer layers, resulting in transverse asymmetric membranes. ...

Lipids as Anchors

In the plasma membrane, the lipids forming the bilayer can also act as an anchor to tether proteins to the membrane. The three main types of lipid anchors ...

The Significance of Membrane Transport

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Describe the structures of fatty acids, triglycerides, phospholipids, and steroids. Explain the functions of lipids in living organisms. Identify some reactions that fatty acids undergo. Relate the structure and function of cell membranes.

SC.912.L.18.3

Ligand Binding Sites

Cofactors and Coenzymes

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Introduction to Enzymes

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Enzymes and Activation Energy

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Introduction to Enzyme Kinetics

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Turnover Number and Catalytic Efficiency

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Catalytically Perfect Enzymes

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Introduction to Mechanisms of Enzyme Catalysis

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Ligand Binding and Linkage

Cooperative Allosteric Transitions

Ribozymes

Enzyme Activity

Biological Catalysts

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Describe the structures of proteins and amino acids. Explain the functions of proteins in living organisms. Identify some reactions that amino acids undergo. Relate the structure and function of enzymes.

SC.912.L.18.4

Chemiosmosis

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Electron Transport Chain: Complex I and II

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electron-transport-chain-complex-iii-and-iv

Electron Transport Chain: Complex III and IV

During the electron transport chain, electrons from NADH and FADH2 are first transferred to complexes I and II, respectively. These two complexes then ...

The Electron Transport Chain

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The Supercomplexes in the Crista Membrane

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ATP Synthase: Structure

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ATP Synthase: Mechanism

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The ADP/ATP Carrier Protein

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ATP Yield

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Discuss the use of chemiosmotic gradients for ATP production in chloroplasts and mitochondria.

SC.912.L.18.5

Fermentation

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Biofuels: Producing Ethanol from Cellulosic Material

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Discuss the role of anaerobic respiration in living things and in human society.

SC.912.L.18.6

Photosynthesis

Autotrophs

Almost all living organisms on Earth depend on photosynthesis, which is the process that converts sunlight energy into a simple sugar called ...

What is Photosynthesis?

All living organisms on Earth are directly or indirectly dependent on photosynthesis. It is the only biological process that can capture energy from ...

The Anatomy of Chloroplasts

Green algae and plants, including green stems and unripe fruit, harbor specialized organelles called chloroplasts to carry out photosynthesis. They ...

Photosystems

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The Photochemical Reaction Center

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The Antenna Complex

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The Z-Scheme of Electron Transport in Photosynthesis

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Identify the reactants, products, and basic functions of photosynthesis.

SC.912.L.18.7

A. All living things are composed of four basic categories of macromolecules and share the same basic needs for life.

B. Living organisms acquire the energy they need for life processes through various metabolic pathways (primarily photosynthesis and cellular respiration).

C. Chemical reactions in living things follow basic rules of chemistry and are usually regulated by enzymes.

D. The unique chemical properties of carbon and water make life on Earth possible.

Electron Carriers in Cellular Energy

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