The Replication of DNA

Base Pairing The strands of the DNA double helix are said to be ‘complimentary’ Each of the two strands has all the info, by the mechanisms of base pairing, to reconstruct the other half Ex: if a dollar bill is torn in half, each half gives an idea of what the other have should look like even though the two halves are not identical Base pairing = attraction between complementary nitrogenous bases that produces a force that holds the two strands of the DNA double helix together

Replication Before a cell divides, it must duplicate its DNA Ensures that each resulting cell will have a complete set of DNA molecules, this is known as replication Replication = process by which DNA is duplicated before a cell divides

Replication DNA synthesis / replication is carried out by a series of enzymes Enzymes separate or ‘unzip’ the two strands of the double helix, insert the appropriate bases and produces covalent sugar-phosphate links to extend the growing DNA chains The enzymes also proofread the bases that have been inserted to ensure that they are paired correctly

Replication W & C stated that replication begins when a molecule of DNA ‘unzips’ The unzipping occurs when the hydrogen bonds between the base pairs are broken and the two strands of the molecule unwind Ex: a strand with the bases T-A-C-G-T-T produces a strand with the complementary bases A-T-G-C-A-A