Name: pyruvate pathways in fermentation
Uploaded: 2025-05-22T09:05:36.000Z
Duration: 1 min 20 s
Channel: JoVE

K12 Standards

Florida Department of Education

High School

Life Science

SC.912.L.18

SC.912.L.18.8

Fates of Pyruvate

El piruvato, el producto final de la glucólisis, puede tener varios destinos metabólicos dependiendo de las condiciones fisiológicas dentro del organismo.
En condiciones aeróbicas, el piruvato se convierte en acetil-coenzima A, que luego se canaliza a través del ciclo de TCA y la cadena de transporte de electrones para producir energía en forma de ATP.
Pero, en condiciones anaeróbicas, la cadena de transporte de electrones no funciona, como se ve en la levadura y las bacterias anaeróbicas. Por lo tanto, el piruvato se fermenta en etanol mientras oxida el NADH en NAD+ . A continuación, el NAD+ se recicla de nuevo a glucólisis.
En la mayoría de los vertebrados, las condiciones temporales de bajo oxígeno desencadenan otra forma de fermentación del piruvato, en la que se fermenta en lactato, produciendo NAD+.
La regeneración de NAD+ durante la fermentación ayuda a las células a seguir produciendo ATP incluso en condiciones de bajo oxígeno a través de la glucólisis.
Durante los niveles bajos de glucosa en la sangre, el piruvato también se puede convertir de nuevo en glucosa 6-fosfato mediante un proceso llamado gluconeogénesis. La glucosa 6-fosfato se convierte en glucosa, que restaura el nivel de glucosa en sangre.

destinos del piruvato

El piruvato es el producto final de la glucólisis, donde la glucosa se oxida a piruvato, reduciendo simultáneamente el NAD+ a NADH. También se producen dos moléculas de ATP mediante fosforilación a nivel de sustrato.

En organismos aeróbicos, el piruvato se metaboliza mediante el ciclo del ácido cítrico para producir coenzimas reducidas NADH y FADH2. Estas coenzimas entonces se oxidan en la cadena de transporte de electrones para producir ATP y, en el proceso, regenerar NAD+ y FAD. Como se observa en algunos tipos de células y organismos, la fermentación reduce el piruvato a lactato en ausencia de oxígeno, oxidando el NADH a NAD+. La regeneración de NAD+ permite que la glucólisis continúe produciendo ATP mediante fosforilación a nivel de sustrato.

Fermentación del ácido láctico

Durante la fermentación del ácido láctico, el piruvato acepta electrones del NADH y se reduce a ácido láctico. Los microbios que realizan la fermentación homoláctica producen sólo ácido láctico como producto de la fermentación; Los microbios que realizan la fermentación heteroláctica producen una mezcla de ácido láctico, etanol y/o ácido acético y CO2. La producción de ácido láctico por parte de la microbiota normal previene el crecimiento de patógenos en determinadas regiones del cuerpo y es importante para la salud del tracto gastrointestinal.

Fermentación de etanol

La fermentación del piruvato en etanol por la levadura Saccharomyces cerevisiae se utiliza en la producción de bebidas alcohólicas y también hace que los productos de pan aumenten debido a la producción de CO2. Fuera de la industria alimentaria, la fermentación de productos vegetales con etanol es importante en la producción de biocombustibles.

Varios productos de fermentación son importantes comercialmente fuera de la industria alimentaria. Por ejemplo, durante la fermentación de acetona-butanol-etanol se producen disolventes químicos como la acetona y el butanol. Los compuestos farmacéuticos orgánicos complejos utilizados en antibióticos (p. ej., penicilina), vacunas y vitaminas se producen mediante fermentación ácida mixta.

Destinos del piruvato

El piruvato es el producto final de la glucólisis, donde la glucosa se oxida a piruvato, reduciendo simultáneamente el NAD+ a NADH. Dos moléculas de ATP también son ...

Education

Educación

JoVE Core

Cell Biology

Biología Celular

Unit 1

Unidad 1

Introduction to Metabolism

Introducción al metabolismo

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

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, some cells and organisms use fermentation to keep energy production going. Fermentation reduces pyruvate to lactate and oxidizes NADH back to NAD+. This regeneration of NAD+ is important because it allows glycolysis to continue making ATP by substrate-level phosphorylation.

In lactic acid fermentation, pyruvate accepts electrons from NADH and becomes lactic acid. Microbes that carry out homolactic fermentation make only lactic acid. Microbes that carry out heterolactic fermentation make a mix of lactic acid, ethanol and/or acetic acid, and CO2. Lactic acid made by normal microbiota can help prevent pathogen growth in some body regions and supports gastrointestinal tract health.

Pyruvate can also be fermented to ethanol by the yeast Saccharomyces cerevisiae. This process is used to make alcoholic beverages and helps bread rise because it releases CO2. Ethanol fermentation of plant products is also important in biofuel production. Other fermentation products have commercial value too. Acetone and butanol are made during acetone-butanol-ethanol fermentation, and complex organic compounds used in antibiotics such as penicillin, vaccines, and vitamins are produced through mixed acid fermentation.

Pyruvate Pathways in Fermentation

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 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 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...

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

Explore how pyruvate is used in aerobic respiration and fermentation, including lactic acid and ethanol fermentation, ATP production, and real-world uses.

Pyruvate Pathways in Fermentation | JoVE K12

cell biology

JoVE Core Biología Celular ilustra procesos celulares complejos mediante completos vídeos animados fáciles de entender. Esta colección se centra en los componentes esenciales de las células y su funcionamiento, incluyendo los orgánulos y las membranas, el transporte celular y el metabolismo energético celular. Todo este material se complementa con los vídeos de científicos en acción, que muestran la aplicación de la biología celular en experimentos reales de investigación.

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

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Fibrous Proteins

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Protein Denaturation

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Role of Proteins in the Human Body

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Mechanical Protein Function

Structural Protein Function

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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?

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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

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Asymmetric Lipid Bilayer

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Lipids as Anchors

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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 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

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

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

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

ADP/ATP carrier or AAC protein is the most abundant carrier protein in the inner mitochondrial membrane. It transports large quantities of ADP and ATP, ...

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

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
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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.

Pyruvate Pathways in Fermentation

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