Unit V: Molecular Genetics · Key Factors •Replication Forks: sites where separation &...
Transcript of Unit V: Molecular Genetics · Key Factors •Replication Forks: sites where separation &...
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Unit V: Molecular Genetics
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Part III: DNA REPLICATION
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Quick Review•A pairs with T•C pairs with G•Hydrogen bonds hold the bases together•One DNA molecule = two strands•Antiparallel (opposite)
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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
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What is DNA Replication?•A process where DNA is copied •In what phase of Interphase is DNA replicated?
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When?•DNA replication occurs during the S phase in Interphase
•Is interphase apart of mitosis?
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Where?•In eukaryotes, DNA replication occurs in the NUCLEUS
•In prokaryotes, DNA replication occurs in the CYTOPLASM
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Steps of DNA Replication
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Step 11. DNA helicase “unzips” the DNA
molecule into two strands•Breaks the Hydrogen bonds between the nitrogenous bases•Forms replication fork
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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
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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
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Step 44. DNA Ligase ”glues” the
new DNA molecules together•Forms Hydrogen bonds
between the nitrogenous bases
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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
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