Glukose Nedbrytning Uten Oksygen

Glukose Nedbrytning Uten Oksygen

• Anaerob celleånding (gjæring): Cells need energy even without oxygen. This process, called anaerobic respiration or fermentation, breaks down pyruvate when pyruvates cannot undergo pyruvate oxidation.

• Generell likning for gjæring: An organic molecule + NADH → reduced organic molecule + NAD. This is an older method of breaking down glucose since oxygen evolved later in evolution.

• Gjæring (fermentering) hos gjær: Yeast and some plant cells have enzymes to remove CO₂ from pyruvate, forming acetaldehyde. Acetaldehyde converts to ethanol, regenerating NAD+ which allows glycolysis to continue. This process produces ethanol in beer and wine. Ethanol is toxic to yeast at high levels, which limits the alcohol concentration in natural products.

• Dannelse av melkesyre: Muscle cells use lactate dehydrogenase to produce lactic acid. This helps glycolysis continue. Prolonged lactic acid production without oxygen leads to muscle cramps due to excess H⁺ ions in the muscle cells.

• Laktat i blodet: The circulatory system carries lactic acid (lactate) from the muscles to the liver. The liver converts lactic acid back into glucose through gluconeogenesis (creating new glucose).

Muskelcelletyper

• Muscle cells (fibers) vary in type. Slow-twitch fibers have higher oxidative phosphorylation, making them more endurance-based found in postural muscles. Fast-twitch fibers rely on glycolysis for energy, making them better suited for short bursts of intense activity, found mainly in muscles used for sprinting.

• Training and muscle adaptation: Long-term endurance training causes an increase in mitochondria and capillaries around muscle fibers, enhancing endurance.

• Glycogen stores: Muscle cells store glycogen for immediate energy for activities; these stores last for approximately 1-2 hours of strenuous exercise.