Glycolysis

Glycolysis is the first step in a process known as cellular respiration. Glycolysis is the process of breaking down (-lysis) glucose (glyco-), a sugar molecule that provides energy for the human body. Glucose is a polymer (made up of a chain of carbons) and therefore it takes multiple steps to break it down into usable energy. There are a total of ten steps in glycolysis. After the final step, the products of the broken down glucose molecule will enter the next step of cellular respiration.

Glycolysis steps 1-10

Glucose molecule

The differences between oxidative phosphorylation, anaerobic glycolysis, and aerobic glycolysis (Warburg effect) is detailed below:

Oxidative phosphorylation

In the presence of oxygen, nonproliferating (differentiated) tissues first metabolize glucose to pyruvate via glycolysis and then completely oxidize most of that pyruvate in the mitochondria to CO2 during the process of oxidative phosphorylation. Because oxygen is required as the final electron acceptor to completely oxidize the glucose, oxygen is essential for this process.

See also

Oxidative phosphorylation.

Anaerobic glycolysis

When oxygen is limiting, cells can redirect the pyruvate generated by glycolysis away from mitochondrial oxidative phosphorylation by generating lactate (anaerobic glycolysis). This generation of lactate during anaerobic glycolysis allows glycolysis to continue (by cycling NADH back to NAD+), but results in minimal ATP production when compared with oxidative phosphorylation.

Aerobic glycolysis

Warburg observed that cancer cells tend to convert most glucose to lactate regardless of whether oxygen is present (aerobic glycolysis). This property is shared by normal proliferative tissues. Mitochondria remain functional and some oxidative phosphorylation continues in both cancer cells and normal proliferating cells. Nevertheless, aerobic glycolysis is less efficient than oxidative phosphorylation for generating ATP. In proliferating cells, approximately 10% of the glucose is diverted into biosynthetic pathways upstream of pyruvate production.

Glycolysis and myalgic encephalomyelitis

Abnormal levels of glycolysis metabolites have been observed in patients with myalgic encephalomyelitis (ME). This suggests that individuals with ME may experience abnormal regulation of glycolysis within their cells..

Another study also indicates impaired pyruvate dehydrogenase function in myalgic encephalopathy/chronic fatigue syndrome

Pyruvate dehydrogenase in ME/CFS

See also

• Cellular respiration

Learn more

• Glycolysis

• Overview of glycolysis

oxidative phosphorylation (OXPHOS) - The oxidative phosphorylation pathway produces more than 95% of a cell's energy in the form of ATP. This is done by the mitochondria, in a process called chemiosmosis.

mitochondria Important parts of the biological cell, with each mitochondrion encased within a mitochondrial membrane. Mitochondria are best known for their role in energy production, earning them the nickname "the powerhouse of the cell". Mitochondria also participate in the detection of threats and the response to these threats. One of the responses to threats orchestrated by mitochondria is apoptosis, a cell suicide program used by cells when the threat can not be eliminated.

mitochondria Important parts of the biological cell, with each mitochondrion encased within a mitochondrial membrane. Mitochondria are best known for their role in energy production, earning them the nickname "the powerhouse of the cell". Mitochondria also participate in the detection of threats and the response to these threats. One of the responses to threats orchestrated by mitochondria is apoptosis, a cell suicide program used by cells when the threat can not be eliminated.

metabolite A chemical compound produced by, or involved in, metabolism. The term is often used to refer to the degradation products of drugs in the body.

See myalgic encephalomyelitis.

An alternate term that is sometimes used for myalgic encephalomyelitis, by people who believe the evidence for inflammation in ME is insufficient. This terminology reflects the belief that the "-itis" suffix implies inflammation.

myalgic encephalopathy An alternate term that is sometimes used for myalgic encephalomyelitis, by people who believe the evidence for inflammation in ME is insufficient. This terminology reflects the belief that the "-itis" suffix implies inflammation.

myalgic encephalomyelitis (M.E.) - A disease often marked by neurological symptoms, but fatigue is sometimes a symptom as well. Some diagnostic criteria distinguish it from chronic fatigue syndrome, while other diagnostic criteria consider it to be a synonym for chronic fatigue syndrome. A defining characteristic of ME is post-exertional malaise (PEM), or post-exertional neuroimmune exhaustion (PENE), which is a notable exacerbation of symptoms brought on by small exertions. PEM can last for days or weeks. Symptoms can include cognitive impairments, muscle pain (myalgia), trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, among others. An estimated 25% of those suffering from ME are housebound or bedbound. The World Health Organization (WHO) classifies ME as a neurological disease.

See chronic fatigue syndrome.