Oncology & Cancer

Scientists solve a 100-year-old mystery about cancer

The year 2021 marks the 100th anniversary of a fundamental discovery that's taught in every biochemistry textbook. In 1921, German physician Otto Warburg observed that cancer cells harvest energy from glucose sugar in a strangely ...

Diseases, Conditions, Syndromes

Physical frailty syndrome: A cacophony of multisystem dysfunction

In the inaugural issue of the journal Nature Aging a research team led by aging expert Linda P. Fried, MD, MPH, dean of Columbia University Mailman School of Public Health, synthesizes converging evidence that the aging-related ...

Oncology & Cancer

Map shows how cancer cells spread through the body

The vast majority of cancer deaths are attributed to metastasis, or the spread of tumors from one organ to another. Determining if a cancer will metastasize has been all but impossible, but if it does, it becomes more difficult ...

Immunology

Obesity impairs immune cell function, accelerates tumor growth

Obesity has been linked to increased risk for over a dozen different types of cancer, as well as worse prognosis and survival. Over the years, scientists have identified obesity-related processes that drive tumor growth, ...

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Metabolism

Metabolism is the set of chemical reactions that occur in living organisms to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories. Catabolism breaks down organic matter, for example to harvest energy in cellular respiration. Anabolism, on the other hand, uses energy to construct components of cells such as proteins and nucleic acids.

The chemical reactions of metabolism are organized into metabolic pathways, in which one chemical is transformed into another by a sequence of enzymes. Enzymes are crucial to metabolism because they allow organisms to drive desirable but thermodynamically unfavorable reactions by coupling them to favorable ones, and because they act as catalysts to allow these reactions to proceed quickly and efficiently. Enzymes also allow the regulation of metabolic pathways in response to changes in the cell's environment or signals from other cells.

The metabolism of an organism determines which substances it will find nutritious and which it will find poisonous. For example, some prokaryotes use hydrogen sulfide as a nutrient, yet this gas is poisonous to animals. The speed of metabolism, the metabolic rate, also influences how much food an organism will require.

A striking feature of metabolism is the similarity of the basic metabolic pathways between even vastly different species. For example, the set of carboxylic acids that are best known as the intermediates in the citric acid cycle are present in all organisms, being found in species as diverse as the unicellular bacteria Escherichia coli and huge multicellular organisms like elephants. These striking similarities in metabolism are most likely the result of the high efficiency of these pathways, and of their early appearance in evolutionary history.

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