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

Glikolizin son ürünü olan piruvat, organizma içindeki fizyolojik koşullara bağlı olarak çeşitli metabolik kaderlere sahip olabilir.
Aerobik koşullar altında, piruvat asetil-koenzim A'ya dönüştürülür ve daha sonra ATP formunda enerji üretmek için TCA döngüsü ve elektron taşıma zinciri boyunca kanalize edilir.
Ancak, anaerobik koşullar altında, elektron taşıma zinciri, maya ve anaerobik bakterilerde görüldüğü gibi çalışmaz. Bu nedenle, piruvat, NADH'yi NAD + 'ya oksitlerken etanol olarak fermente edilir. NAD + daha sonra glikolize geri dönüştürülür.
Omurgalıların çoğunda, geçici düşük oksijen koşulları, laktat halinde fermente edildiği ve NAD + ürettiği başka bir piruvat fermantasyon biçimini tetikler.
Fermantasyon sırasında NAD + 'nın yenilenmesi, hücrelerin glikoliz yoluyla düşük oksijen koşullarında bile ATP üretmeye devam etmesine yardımcı olur.
Düşük kan şekeri seviyeleri sırasında, piruvat, glukoneogenez adı verilen bir işlemle tekrar glikoz 6-fosfata dönüştürülebilir. Glikoz 6-fosfat daha sonra kan şekeri seviyesini geri kazandıran glikoza dönüştürülür.

piruvat'ın akıbeti

Piruvat, glukozun piruvata oksitlendiği ve aynı anda NAD+'nın NADH'ye indirgendiği glikolizin son ürünüdür. Substrat düzeyinde fosforilasyonla iki ATP molekülü de üretilir. Aerobik organizmalarda piruvat, indirgenmiş koenzimler NADH ve FADH2'yi üretmek için sitrik asit döngüsü yoluyla metabolize edilir. Bu koenzimler daha sonra ATP üretmek için elektron taşıma zincirinde oksitlenir ve bu süreçte NAD+ ve FAD'ı yeniden üretir. Bazı hücre tiplerinde ve organizmalarda görüldüğü gibi fermantasyon, oksijen yokluğunda piruvat'ı laktata indirgeyerek NADH'yi NAD+'ya oksitler. NAD+'nın yenilenmesi, glikolizin substrat seviyesinde fosforilasyon yoluyla ATP üretmeye devam etmesine izin verir. Laktik Asit Fermantasyonu Laktik asit fermantasyonu sırasında piruvat, NADH'den elektronları alır ve laktik asite indirgenir. Homolaktik fermantasyon gerçekleştiren mikroplar, fermantasyon ürünü olarak yalnızca laktik asit üretirler; Heterolaktik fermantasyon gerçekleştiren mikroplar laktik asit, etanol ve/veya asetik asit ve CO2 karışımı üretir. Normal mikrobiyotanın laktik asit üretimi, vücudun belirli bölgelerinde patojenlerin büyümesini engeller ve gastrointestinal sistemin sağlığı açısından önemlidir. Etanol Fermantasyonu Piruvatın Saccharomyces cerevisiae mayası tarafından etanol fermantasyonu, alkollü içeceklerin üretiminde kullanılmakta ve aynı zamanda CO2 üretimi nedeniyle ekmek ürünlerinin yükselmesine neden olmaktadır. Gıda endüstrisinin dışında, biyoyakıt üretiminde bitkisel ürünlerin etanol fermantasyonu önemlidir. Çeşitli fermantasyon ürünleri, gıda endüstrisinin dışında ticari açıdan da önemlidir. Örneğin aseton-bütanol-etanol fermantasyonu sırasında aseton ve bütanol gibi kimyasal çözücüler üretilir. Antibiyotiklerde (örneğin penisilin), aşılarda ve vitaminlerde kullanılan karmaşık organik farmasötik bileşikler, karışık asit fermantasyonu yoluyla üretilir. Bu metin <a href="https://openstax.org/books/biology-2e/pages/7-5-metabolism-without-oxygen">Openstax, Biology 2e, Bölüm 7.5: Oksijensiz Metabolizma</a>

Piruvat'ın Akıbeti

Pirüvat, glikozun piruvata oksitlendiği ve aynı anda NAD + 'yı NADH'ye indirgediği glikolizin son ürünüdür. İki ATP molekülü de ...

Education

JoVE Core

Cell Biology

Hücre Biyolojisi

Unit 1

Ünite 1

Introduction to Metabolism

Metabolizmeye Giriş

KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

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

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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...

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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

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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 Hücre Biyolojisi, anlaşılması kolay ancak kapsamlı animasyonlu video derslerde karmaşık hücresel süreçleri gösterir. Bu koleksiyon, organeller ve zarlar, hücresel taşıma ve hücre enerjileri dahil olmak üzere hücrelerin temel bileşenlerine ve işlevlerine odaklanır. Gerçek dünya araştırma deneylerinde hücre biyolojisinin uygulanmasını gösteren bilim insanı eylem videoları ile tamamlanmaktadır.

Macromolecules

Biomolecules
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Polymers

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SC.912.L.18.5

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SC.912.L.18.6

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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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