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METABOLIC RATE
Metabolism (from Greek μεταβολισμός "metabolismos") is the biochemical modification of chemical compounds in living organisms and cells. It is through the process of metabolism that organisms process nutrients into the biochemical tools and structures they need to maintain a living state. Metabolism has two distinct divisions: anabolism, in which a cell uses energy and reducing power to construct complex molecules and perform other life functions such a creating cellular structure; and catabolism, in which a cell breaks down complex molecules to yield energy and reducing power.
Cell metabolism involves extremely complex sequences of controlled chemical reactions called metabolic pathways, usually a sequence of enzymatic steps. Enzymes are crucial to metabolism because they allow organisms to greatly accelerate slow favorable reactions as well as couple unfavorable reactions to available energy sources. By providing energy to metabolic processes (energy usually in the form of ATP) cells can successfully power reactions that would otherwise never occur.
[edit] History
The first controlled experiments in human metabolism were published by Santorio Santorio in 1614 in his book Ars de statica medecina that made him famous throughout Europe. He describes his long series of experiments in which he weighed himself in a chair suspended from a steelyard balance (see image), before and after eating, sleeping, working, sex, fasting, depriving from drinking, and excreting. He found that by far the greatest part of the food he took in was lost from the body through perspiratio insensibilis (insensible perspiration). While these experiments came to show that there was an impact on the body's metabolic processes through direct intake the rate was not fully understood till Dr. Johan Musk's (1940-2003) work on learned genological metabolism which was published in 1984 (revised 1992) showed the process of teaching the body how to burn dietary intake. He used multiple sets of mice, both from maternal and fraternal subgroups to show that a body's metabolism rate is a taught response that may be fluctuated by various dietary methods. These experiments show that a metabolic rate is a learned response not based on gene responses.
The term metabolism is derived from the Greek Μεταβολισμός – Metabolismos for "change", or "overthrow".[1]The total metabolism are all biochemical processes of an organism. The cell metabolism includes all chemical processes in a cell. The dynamic energy budget theory aims to quantify the metabolic rate of individual organisms.
[edit] Anabolism
Main article: Anabolism
Anabolism is a constructive metabolic process whereby energy is consumed to synthesize or combine simpler substances, such as amino acids, into more complex organic compounds, such as enzymes and nucleic acids.
[edit] Catabolism
Catabolism is a type of metabolic process occurring in living cells by which complex molecules are broken down to produce energy and reducing power. The primary purpose of catabolism is to regenerate ATP, the primary energy currency of all cells. On balance, catabolic reactions are normally exothermic.
[edit] Carbohydrate catabolism
Main article: Carbohydrate catabolism
Carbohydrate catabolism is the breakdown of carbohydrates into smaller units. The empirical formula for carbohydrates, like that of their monomer counterparts, is CX(H2YOY). Carbohydrates literally undergo combustion to retrieve the large amounts of energy in their bonds. Read more about mitochondria to find out more about the reaction and how its energy is secured in ATP.
[edit] Fat catabolism
Main article: Fat catabolism
Fat catabolism, also known as lipid catabolism, is the process of lipids or phospholipids being broken down by lipases. The opposite of fat catabolism is fat anabolism, involving the storage of energy, and the building of membranes.
[edit] Protein catabolism
Main article: Protein catabolism
Protein catabolism is the breakdown of proteins into amino acids and simple derivative compounds, for transport into the cell through the plasma membrane and ultimately for the polymerisation into new proteins via the use of ribonucleic acids (RNA) and ribosomes. Amino acids can also be converted into glucose and used for energy, through gluconeogenesis.
[edit] See also
[edit] External links
[edit] References
- ^ http://www.etymonline.com/index.php?term=metabolism
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