Related topics: genes · protein · cells · amino acids · diabetes

Breaking down glycosides in the gut and in nature

Rarely does a tool become more useful when it's broken, but that's just the case with C-glycoside, a molecule found in many plants, foods, and medicines. To be used by the body, C-glycosides must be broken down. Researchers ...

'Feeling' the living cell's life cycle using optical tweezers

Living cells are the basic building blocks of all organisms. We, as humans, are essentially a collection of trillions of living cells: and all these cells emerge from a single fertilized egg. This means that "mitosis" (or ...

AI is helping to quantify enzyme activity

Without enzymes, an organism would not be able to survive. It is these biocatalysts that facilitate a whole range of chemical reactions, producing the building blocks of the cells. Enzymes are also used widely in biotechnology ...

New biomarker for severe COVID-19

During the pandemic, it has become evident that people with cardiovascular disease and obesity are at much higher risk of developing very severe, even fatal COVID-19 disease. Researchers at Karolinska Institutet have identified ...

Complex dynamics turn lake water green and brown

Many lakes and ponds are changing colors—from pleasant blue or clear to murky brown or green, caused by runoff of nutrients and carbon, coupled with warmer temperatures.

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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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