ABSTRACT
This chapter describes the protein machines that replicate and repair the cell's deoxyribonucleic acid (DNA). It deals with a brief discussion of the changes that occur in DNA as it is passed down from generation to generation. During DNA replication inside a cell, each of the two original DNA strands serves as a template for the formation of an entire new strand. Initially, the simplest mechanism of DNA replication seemed to be the continuous growth of both new strands, nucleotide by nucleotide, at the replication fork as it moves from one end of a DNA molecule to the other. The importance of DNA repair is evident from the large investment that cells make in DNA repair enzymes. In homologous recombination, genetic exchange takes place between a pair of homologous DNA sequences, that is, DNA sequences similar or identical in nucleotide sequence.
