DNA ReplicationReplication is the process by which DNA is

copied.Watson and Crick realized that a single

strand can serve as a template or pattern for a new strand.

Replication assure that every cell has a complete set of identical genetic information.

DNA is divided in the 46 chromosomes that are replicated during the S phase of the cell cycle.

Proteins carries out Replication

DNA store informationEnzymes and other proteins do the

replication.Enzymes start unzipping the double helix to

separate the strand of DNA. Proteins hold the strand apart while the strand serves as a template.

Nucleotides are floating free in the nucleus and can pair up with the nucleotides of the existing DNA strands.

DNA polymerase bonds the new nucleotides together.

End results is two molecules of DNA exactly like the original double strand.

DNA ReplicationIn eukaryotes (similar to prokaryotes)I. Enzymes begin to unzip the double helix at

numerous places along the chromosome called origins of replication.

The hydrogen bonds connecting base pair are broken. The original molecules separates and the bases on each strand are exposed. It unzips like a suitcase 2 direction at the same time.

II. Free nucleotides pair with the base exposed as the template strand unzip. DNA polymerase bonds the nucleotides together and form a new strand complementary to the template.

DNA ReplicationOn one template, DNA replication occurs in a

smooth, continuous way in one direction. Leading Strand – continuous strand,

The other template, replication occurs in a discontinuous piece by piece way in the opposite direction. Replication of this strand is known as Lagging.

Two identical molecules of DNA result, one strand from the original structure and one new strand. It is Semi-conservative because one old strand is conserved and one new strand is made.

DNA ReplicationDNA replication is fast and accurate.

Replication has a built-in proofreading function to correct errors. Occasionally, the wrong nucleotide is added to the new strand of DNA. DNA polymerase can detect the error, remove the incorrect nucleotide and replace the nucleotide with the correct one. Errors are limited to 1 error per 1 billion nucleotide.