Molecular evolution: codes, clocks, genes and genomes.

The discoveries, advancements and continuing controversies in the field of molecular evolution are reviewed. Topics summarized are (1) the evolution of the genetic code, (2) gene evolution including the demonstration of homology, estimation of sequence divergence, phylogenetic trees, the molecular clock and the origin of genes and gene families by various genetic mechanisms, and (3) eukaryotic genome evolution, including the highly repeated satellite sequences, the interspersed and potentially mobile repeated sequences and the unique sequence fraction of the genome.