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

Pyruvat, das Endprodukt der Glykolyse, kann je nach den physiologischen Bedingungen im Organismus mehrere metabolische Schicksale haben.
Unter aeroben Bedingungen wird Pyruvat in Acetyl-Coenzym A umgewandelt, das dann durch den TCA-Zyklus und die Elektronentransportkette geleitet wird, um Energie in Form von ATP zu erzeugen.
Unter anaeroben Bedingungen funktioniert die Elektronentransportkette jedoch nicht, wie bei Hefen und anaeroben Bakterien zu sehen ist. Pyruvat wird also zu Ethanol fermentiert, während NADH zu NAD+ oxidiert wird. NAD+ wird dann wieder zur Glykolyse zurückgeführt.
Bei den meisten Wirbeltieren lösen vorübergehend niedrige Sauerstoffbedingungen eine andere Form der Pyruvatfermentation aus, bei der es zu Laktat fermentiert wird, wobei NAD+ entsteht.
Die Regeneration von NAD+ während der Fermentation hilft den Zellen, ATP auch unter sauerstoffarmen Bedingungen über die Glykolyse weiter herzustellen.
Bei niedrigen Blutzuckerspiegeln kann Pyruvat auch durch einen Prozess namens Glukoneogenese wieder in Glukose-6-Phosphat umgewandelt werden. Glukose-6-phosphat wird dann in Glukose umgewandelt, wodurch der Blutzuckerspiegel wiederhergestellt wird.

schicksale von pyruvat

Pyruvat ist das Endprodukt der Glykolyse, bei der Glukose zu Pyruvat oxidiert und gleichzeitig NAD+ zu NADH reduziert wird. Zwei ATP-Moleküle werden auch durch Phosphorylierung auf Substratebene hergestellt.

In aeroben Organismen wird Pyruvat über den Zitronensäurezyklus verstoffwechselt, um reduzierte Coenzyme NADH und FADH2 zu produzieren. Diese Coenzyme werden dann in der Elektronentransportkette oxidiert, um ATP zu produzieren und dabei NAD+ und FAD zu regenerieren. Wie bei einigen Zelltypen und Organismen zu beobachten ist, reduziert die Fermentation Pyruvat in Abwesenheit von Sauerstoff zu Laktat und oxidiert NADH zu NAD+. Die Regeneration von NAD+ ermöglicht der Glykolyse, weiterhin ATP durch Phosphorylierung auf Substratebene herzustellen.

Milchsäuregärung

Bei der Milchsäuregärung nimmt Pyruvat Elektronen von NADH auf und wird zu Milchsäure reduziert. Mikroben, die eine homolaktische Fermentation durchführen, produzieren als Fermentationsprodukt ausschließlich Milchsäure; Mikroben, die eine heterolaktische Fermentation durchführen, produzieren eine Mischung aus Milchsäure, Ethanol und/oder Essigsäure und CO2. Die Milchsäureproduktion durch die normale Mikrobiota verhindert das Wachstum von Krankheitserregern in bestimmten Körperregionen und ist wichtig für die Gesundheit des Magen-Darm-Trakts.

Ethanol-Fermentation

Die Ethanolvergärung von Pyruvat durch die Hefe Saccharomyces cerevisiae wird bei der Herstellung alkoholischer Getränke eingesetzt und lässt durch die CO2-Produktion auch Brotprodukte aufgehen. Außerhalb der Lebensmittelindustrie ist die Ethanolfermentation pflanzlicher Produkte wichtig für die Biokraftstoffproduktion.

Mehrere Fermentationsprodukte sind außerhalb der Lebensmittelindustrie kommerziell wichtig. Beispielsweise entstehen bei der Aceton-Butanol-Ethanol-Fermentation chemische Lösungsmittel wie Aceton und Butanol. Komplexe organische pharmazeutische Verbindungen, die in Antibiotika (z. B. Penicillin), Impfstoffen und Vitaminen verwendet werden, werden durch gemischte Säurefermentation hergestellt.

Dieser Text ist adaptiert von <a href="https://openstax.org/books/biology-2e/pages/7-5-metabolism-without-oxygen">Openstax, Biology 2e, Section 7.5: Metabolism without oxygen</a>

Schicksale von Pyruvat

Pyruvat ist das Endprodukt der Glykolyse, bei der Glukose zu Pyruvat oxidiert wird, wodurch NAD+ gleichzeitig zu NADH reduziert wird. Zwei Moleküle von ATP sind auch ...

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

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

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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;

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fats as energy storage molecules

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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,...

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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 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.

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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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