Enzyme
From EvoWiki
Contents |
Introduction
An Enzyme (Gk: In Ferment) is a biological Catalyst, that is, it speeds up chemical reactions in living things. Enzymes are crucial because without them most reactions in the body would occur slowly, or not occur at all.
Structure of Enzymes
Enzymes are either protein molecules (or protein complexes) or RNA molecules (ribozymes). This means that their structure is determined by an organism's genes, and individual enzymes can be matched with the genes that produced them. This also means that variation in genes is linked directly with changes in enzyme structure.
Enzymes and Evolution
Enzymes, and other proteins, are responsible for producing the phenotype of an individual. When an individual is growing, particularly as an fetus (baby in the womb) enzymes are responsible for producing other macromolecules, converting chemicals in the cells and perhaps most importantly for controlling which genes are expressed. There is a chain between genotype and phenotype, with enzymes a crucial intermediate step. Changes in genotype are capable of changing the phenotype because enzymes behave differently depending on their structure.
Some existing nucleic acid molecules in cells act as catalysts that are able to alter chemical bonds in nucleic acids and proteins. The ability of nucleic acids to function like protein enzymes has implications for abiogenesis. Early forms of life may not have made proteins and may have relied on some form of nucleic acid-catalyzed metabolism. Proteins with enzymatic activity may have been a later evolutionary innovation. More enzymatically efficient proteins might have replaced most of the enzymatically active nucleic acids of early life forms.
See also
External Links
References & Further Reading
- More on enzymes can be found in any standard biology or biochemistry textbook.
- Garrett, R. & Grisham C., 1999, Biochemistry, 2nd ed.. Saunders College Pub.
