DNA Replication Complementary Base Pairing SemiConservative Replication Topoisomerase

DNA Replication

Complementary Base Pairing

Semi-Conservative Replication

• • Topoisomerase – DNA helix DNA Helicase – parent DNA strands DNA polymerase – new strand DNA ligase – joins adjacent together

Sequence of Events 1. 2. 3. 4. Topoisomerase the DNA molecule DNA then unzips DNA while single stranded binding (ssb) proteins attach to each template strand to prevent the strands from. DNA finds the origin of replication (the site where the replication will initiate from on both strands) DNA polymerase adds thousands of new which are to the template strands in the ’ to ’ direction. • 5. Since DNA replication happens from 5’ to 3’, one of the template strands ( strand) is synthesized , while the other template strand ( strand) is synthesized in small called fragments. • 6. DNA polymerase also has a proof-reading function Okazaki fragments are also synthesized in the 5’ to 3’ direction Once completed, the okazaki fragments on the lagging strand are joined together by DNA. • Note that the single nucleotides are joined together by DNA polymerase in the okazaki fragments and on the leading strand, while okazaki fragments are joined together by DNA ligase.

Recombinant DNA • Recombinant DNA is the general name for taking a piece of one DNA, and it with another strand of DNA. • By combining two or more different strands of DNA, scientists are able to create a strand of DNA. • The most common recombinant process involves combining the DNA of two different.

Scientists can now use this cell to create a lot of human growth hormone (protein) for research purposes

Uses of Recombinant DNA • Recombinant DNA has been gaining in importance over the last few years, and recombinant DNA will only become more important in the 21 st century as genetic diseases become more prevelant and agricultural area is reduced. Below are some of the areas where Recombinant DNA will have an impact. – – – – – Better Crops (drought & heat resistance) Recombinant Vaccines (ie. Hepatitis B) Prevention and cure of sickle cell anemia Prevention and cure of cystic fibrosis Production of clotting factors Production of insulin Production of recombinant pharmaceuticals Plants that produce their own insecticides Germ line and somatic gene therapy