Page 3 - Academic Press Encyclopedia of Physical Science and Technology 3rd BioChemistry

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Encyclopedia of Physical Science and Technology EN002H-54 May 17, 2001 20:22

Bioenergetics

Richard E. McCarty
Eric A. Johnson
Johns Hopkins University

I. Catabolic Metabolism: The Synthesis of ATP
II. Photosynthesis
III. Origin of Mitochondria and Chloroplasts
IV. Illustrations of the Uses of ATP: Ion Transport,
Biosynthesis, and Motility
V. Concluding Statements

GLOSSARY BIOENERGETICS,anamalgamationofthetermbiolog-
ical energetics, is the branch of biology and biochemistry
Adenosine 5 -triphosphate (ATP) The carrier of free that is concerned with how organisms extract energy from

energy in cells. their environment and with how energy is used to fuel the
Bioenergetics The study of energy relationships in living myriad of life’s endergonic processes. Organisms may be
systems. usefully divided into two broad groups with respect to
Chloroplasts The sites of photosynthesis in green how they satisfy their need for energy. Autotrophic organ-
plants. isms convert energy from nonorganic sources such as light
Ion transport The movement of ions across biological or from the oxidation of inorganic molecules to chemical
membranes. energy. As heterotrophic organisms, animals must ingest
Metabolism The total of all reactions that occur in cells. and break down complex organic molecules to provide the
Catabolic metabolism is generally degradative and ex- energy for life.
ergonic, whereas anabolic metabolism is synthetic and Interconversions of forms of energy are commonplace
requires energy. in the biological world. In photosynthesis, the electro-
Mitochondria Sites of oxidative (catabolic) metabolism magnetic energy of light is converted to chemical energy,
in cells. largely in the form of carbohydrates, with high overall
Photosynthesis Light-driven synthesis of organic mole- efficiency. The energy of light is used to drive oxidation–
cules from carbon dioxide and water. reduction reactions that could not take place in the dark.
Plasma membrane The barrier between the inside of Light energy also powers the generation of a proton
cells and the external medium. electrochemical potential across the green photosynthetic

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