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Unit V: Molecular Genetics
Part III: DNA REPLICATION
Quick Review•A pairs with T•C pairs with G•Hydrogen bonds hold the bases together•One DNA molecule = two strands•Antiparallel (opposite)
Key Factors•Replication Forks: sites where separation & replication of DNA occur•DNA Polymerase:
1. Joins nucleotides to produce new DNA molecule2. “Proofreads” each new strand to make sure that each new strand of DNA
is identical to the original
What is DNA Replication?•A process where DNA is copied •In what phase of Interphase is DNA replicated?
When?•DNA replication occurs during the S phase in Interphase
•Is interphase apart of mitosis?
Where?•In eukaryotes, DNA replication occurs in the NUCLEUS
•In prokaryotes, DNA replication occurs in the CYTOPLASM
Steps of DNA Replication
Step 11. DNA helicase “unzips” the DNA
molecule into two strands•Breaks the Hydrogen bonds between the nitrogenous bases•Forms replication fork
Step 22. Each separated strand now
serves as a template to produce new strands!•Primase = enzyme that acts as
the “green light” for replication to start
Step 33. DNA Polymerase attaches
to the single strands•Help make two new DNA strands
by base pairing• A-T, G-C
•New double strands of DNA are IDENTICAL
Step 44. DNA Ligase ”glues” the
new DNA molecules together•Forms Hydrogen bonds
between the nitrogenous bases
Results In…•2 IDENTICAL DNA molecules•Each molecule is made up of one old strand and one new strand
• https://www.youtube.com/watch?v=5qSrmeiWsuc