GLOSSARY :: P ::
Phenotype: The physical constitution of an organism as determined by the interaction of its genetic constitution and the environment.
Phylogenesis: The sequence of events involved in the evolution of a species. See Species.
Plasmid: Autonomously replicating, extrachromosomal circular DNA molecules, distinct from the normal bacterial genome and nonessential for cell survival under nonselective conditions. Some plasmids are capable of integrating into the host genome. A number of artificially constructed plasmids are used as cloning vectors.
Polymer: A molecule made up of smaller units bonded to form a chain.
Polymerase Chain Reaction (PCR): A reaction that uses the enzyme DNA polymerase to catalyze the formation of more DNA strands from an original one by the execution of repeated cycles of DNA synthesis.
Procaryotes: Simple organisms that lack a distinct nuclear membrane and other organelles. See Eucaryotes.
Protein: A polymer compound composed of 20 amino acids (actually of more amino acids, but they result from additional chemical modification). Proteins are essential for a cell to live. They form its skeleton, catalyze chemical reactions, perform regulatory and transportation functions. Each protein molecule in the living cell has a complex spatial structure. See Polymer, Amino Acids.
Proteom: The set of all the proteins synthesized in an organism (analogous to genome). See Genome.
Proteomics: Total protein analysis; it reflects the dynamic situation of a cell, providing information regarding the rate of expression and regulation of individual cell proteins.