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

Something old, something new in the ocean's blue

Charles Darwin suspected something in the "clear blue water" of the ocean that was even smaller than the protozoa he could see under the microscope. "Today we know that every liter of ocean water is swarming with hundreds ...

Study tracks evolutionary history of metabolic networks

By analyzing how metabolic enzymes are built and organized, researchers have reconstructed the evolutionary history of metabolism. Their study shows how metabolic networks—which drive every cellular process from protein ...

The sweet taste of innovation

Would that ice-cold bottle of soda taste as refreshing, knowing that it contains 65 grams (5 tablespoons) of added sugar? With a new U.S. food-labeling policy set to kick in, public health groups are banking on the answer ...

A rat's brain, on and off methamphetamine

Drug addiction is a vicious cycle of reward and withdrawal. Chronic users often relapse because of the unpleasant physical and psychological symptoms they experience when they stop taking the drug. Now, researchers report ...

Shipment tracking for 'fat parcels' in the body

Without fat, nothing works in the body: Fats serve as energy suppliers and important building blocks, including for the envelopes of living cells. Numerous diseases are related to disorders in fat metabolism such as obesity ...

CRISPR-BEST prevents genome instability

Even though CRISPR technologies allow for better manipulation of genomes with many positive effects on modern drug development and the discovery of new and better antibiotics, significant problems such as genome instability ...

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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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