Page 67 - General Biochemistry
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Chapter 4
BIOENERGETICS
Bioenergetic processes biological oxidation
• Metabolism is the entire network of chemical reactions carried out by living
cells. Metabolism also includes coordination, regulation and energy
requirement.
• Metabolites are small molecule intermediates in the degradation and
synthesis of polymers.
Most organisms use the same general pathway for extraction and utilization of
energy.
All living organisms are divided into two major classes:
• Autotrophs – can use atmospheric carbon dioxide as a sole source of
carbon for the synthesis of macromolecules. Autotrophs use the sun energy
for biosynthetic purposes.
• Heterotrophs – obtain energy by ingesting complex carbon-containing
compounds. Heterotrophs are divided into aerobs and anaerobs.
Common features of organisms
1. Organisms or cells maintain specific internal concentrations of inorganic
ions, metabolites and enzymes.
2. Organisms extract energy from external sources to drive energy-consuming
reactions.
3. Organisms grow and reproduce according to instructions encoded in the
genetic material.
4. Cells are not static, and cell components are continually synthesized and
degraded (i.e. undergo turnover).
A sequence of reactions that has a specific purpose (for instance: degradation of
glucose, synthesis of fatty acids) is called metabolic pathway.
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