Presentation on theme: "DNA Review What does DNA store that is important? If a DNA strand read AGT-CCG-GTA what would the complimentary strand read? What holds the nitrogen bases."— Presentation transcript:
DNA Review What does DNA store that is important? If a DNA strand read AGT-CCG-GTA what would the complimentary strand read? What holds the nitrogen bases together? What are the 3 components of a nucleotide?
DNA Replication DNA Replication- the process of making a copy of DNA Why is this important? – Cells need to copy their DNA for mitosis (growth, repair, and maintenance) Three steps: – Double helix unwinds and DNA helicase opens the strand – DNA polymerases add nucleotides back – Polymerases detach once replication is complete – You end with 2 stands of identical DNA strands
DNA Replication Step 1: The double helix must unwind before replication can begin. DNA helicases are enzymes that open the double helix by breaking the hydrogen bonds that hold the complimentary bases together (think of a zipper) Replication goes from 5’ to 3’
DNA Replication Step 1 con’t: Once separated, additional proteins hold the strands apart. Where the double helix separates is called a replication fork (because of it’s Y shape)
DNA Replication Step 2: At the replication fork enzymes called DNA polymerases move along each of the DNA strands. DNA polymerases add nucleotides to the exposed bases according to the base pair rules
DNA Replication Step 3: Step 2 continues until all DNA has been copied and the polymerases detach Produces 2 DNA molecules that are identical to each other and the original strand