Dr. Juan Lozano

DNA Replication and Repair
Overview of DNA Replication
Genetic information is transmitted from parent to progeny by replication of parental DNA, a process in which two daughter DNA molecules areproduced that are each identical to the parental DNA molecule. During DNA replication, the two complementary strands of parental DNA are pulled apart. Each of these parental strands is then used as atemplate for the synthesis of a new complementary strand (semiconservative replication). During cell division each daughter cell receives one of the two identical DNA molecules.

Replication ofprokaryotic and eukaryotic chromosomes
The overall process of DNA replication in prokariotes and eukaryotes had many differences.
The bacterial chromosome is a closd, double-stranded circular DNAmolecule having a single origin of replication. Separation of the two parental strands of DNA, creates two replication forks, that move away from each other in opposite directions around the circle.Replication is, thus, a bidirectional process. The two replication forks eventually meet, resultin in the production of two identical circular molecules of DNA.
Each eukaryotic chromosome contains onelinear molecule of dsDNA, having multiple origins of replication. Bidirectional replication occurs by means of a pair of replication forks produced at each origin. Completion of the process results in theproduction of two identical linear molecules of dsDNA (sister chromatids). DNA replication occurs in the mucleus during the S phase of the eukaryotic cell cycle. The two identical sisters areseparated from each other when the cell divides during the mitosis.

Comparison of the DNA and RNA synthesis
The overall procees of DNA replication requires the synthesis of both DNa and RNA. These twotypes of nucleic acids, are synthesized by DNa polymerases and RNA polymerases, respectively.
DNA nucleic acid synthesis 5’>3’ with DNA polymerase
RNA RNA polymerase
Required template copied...