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Carbohydrate Catabolism01:30

Carbohydrate Catabolism

Carbohydrate catabolism is a fundamental process in cellular metabolism that enables energy extraction from glucose through two primary pathways: cellular respiration and fermentation. Both pathways begin with glycolysis, which operates independently of oxygen availability.Glycolysis: A Shared Starting PointGlycolysis is an oxygen-independent process that breaks down glucose into two molecules of pyruvic acid. During this process, a net gain of two ATP molecules and two NADH molecules is...
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Sugars as Energy Storage Molecules01:10

Sugars as Energy Storage Molecules

Sugar (a simple carbohydrate) metabolism (chemical reactions) is a classic example of the many cellular processes that use and produce energy. Living things consume sugar as a major energy source because sugar molecules have considerable energy stored within their bonds. Consumed carbohydrates have their origins in photosynthesizing organisms like plants. During photosynthesis, plants use the energy of sunlight to convert carbon dioxide gas into sugar molecules, like glucose. Because this...
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Carbohydrate Metabolism01:36

Carbohydrate Metabolism

Carbohydrates are polymers composed of molecules containing atoms of carbon, hydrogen and oxygen. One gram of carbohydrate can provide four kilo-calories of energy, which makes it the most efficient instant energy source.
Starch accounts for approximately 60% of the carbohydrates consumed by humans. Since amylase enzymes cannot function in the stomach's acidic environment, starch can only be digested in the mouth and small intestine. Simple sugars are found naturally in milk and fruits in...
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Glucose Transporters01:27

Glucose Transporters

Glucose transporters facilitate the transport of glucose across the cell membrane. In addition to glucose, some glucose transporters can also aid the movement of other hexoses such as fructose, mannose, and galactose.
Facilitated diffusion-glucose transporters (GLUTs) are encoded by the solute-linked carrier (SLC) family 2, subfamily A gene family, or SLC2A. The 14 GLUT protein members are distributed into three classes:
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The Citric Acid Cycle02:36

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 molecules, one FADH2 molecule, and two CO2 molecules.
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Energy-requiring Steps of Glycolysis01:20

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 occurs in the cytosol of the cell over two phases: an energy-requiring phase and an energy-releasing phase. Over the first three steps, glucose is converted into different forms and attached to two phosphate groups donated by two ATP molecules, resulting in an unstable sugar. In the next two stages, the unstable sugar splits into two sugar...
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