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37 Cards in this Set
- Front
- Back
Conservative Replication
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- G1: 2 bands - G2: 2 bands - one daughter has 2 old strands - the others have 2 new strands |
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Semiconservative Replication
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- G1: 1 mixed band - G2: 1 pure band above 1 mixed band - two daughters have one new and one old - two daughters have two new strands |
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Dispersive Replication
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- G1: one mixed band - G2: one mixed band (3:1) - all daughters have mixed bands of new and old |
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Replication in prokaryotes
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- begins at a point, replicates bidirectionally simultaneously, and ends at the terminus |
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What is referred to as Theta (ø)
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- the replicating chromosome
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Reverse Transcriptase
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- RNA dependent DNA polymerase
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RNA Replicase
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- RNA dependent RNA polymerase
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DNA Transcriptase
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- DNA dependent RNA polymerase
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DNA Replicase
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- DNA dependent DNA polymerase
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Template Strand
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- 3' to 5' direction - non coding or antisense strand |
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Non-Template Strand
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- 5' to 3' direction - coding or sense strand |
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__(1)__ is upstream and __(2)__ is downstream
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(1) 5' (2) 3' |
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DNA Polymerases (in general)
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- can only elongate a strand using an RNA primer - can only attach nucleotides in 5' to 3' direction |
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DNA Polymerase I
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- essential (secondary) role in replication - removes RNA primers ad fills gaps with DNA - 5' to 3' polymerase activity - 3' to 5' exonuclease activity (removes errors) - 5' to 3' exonuclease activity (fills gaps between Okazaki fragments with DNA) |
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DNA Polymerase II
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- exclusively repairs DNA - 5' to 3' polymerase activity - 3' to 5' exonuclease activity |
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DNA Polymerase III
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- major replication enzyme in both strands - 5' to 3' polymerase activity - 3' to 5' exonuclease activity |
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DNA-A Protein (in Bacteria)
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- binds to DNA-A boxes within the origin to initiate DNA replication
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DNA-B Protein (in Bacteria)
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- helicase - separates double stranded DNA (dsDNA) by disrupting the H bonds - uses ATP |
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DNA-C Protein (in Bacteria)
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- aids DNA-A in recruitment of DNA helices (DNA-B) to the origin to initiate the complex
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oriC (in Bacteria)
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- wraps around DNA-A monomers
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Topoisomerase
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- gyrase - removes positive supercoiling ahead of the replication fork - releases coil stress caused by replication - allows for unchaining of DNA (decatenation) |
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What is the order of DNA replication in bacteria?
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(1) primase (2) DNA Pol III (3) DNA-A (4) DNA-B (helicase) (5) Single Strand Binding Protiens (SSBP) (6) DNA ligase |
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Initiation
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- begins at origin of repliction - helicase unwinds DNA - SSBP bind to single strands - DNA pol III engages the separated portion |
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Elongation
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- leading strand: RNA primer is placed (primase) then replication proceeds continuously - lagging strand: multiple primers are placed and Okazaki fragments are formed (semi-discontinuous) - strands are proof read then RNA primers are replaced (DNA pol I) |
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Primosome
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- helicase + primase |
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Replisome
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DNA Pol III + primosome
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RNA Primers
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- 5' end is closest to replication fork - enzymatically removed and replaced with correct DNA nucleotides |
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DNA Ligase
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- seals gaps with phosphodiester bonds between adjacent 5'-P and 3'-OH groups - covalently attaches adjacent Okazaki fragments |
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Termination
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- theta replication finishes with Y junction halting replication at mid point between strands - ter site contains termination sequences which terminate replication when bound by tus |
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Tus
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- binds to ter sequences and prevents advancement of replication fork
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Decatenation
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- unlinking of chains
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DNA Replication (in general)
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- has multiple origins of replication - is bidirectional |
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Replication in Telomeres
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- telomeric DNA sequences are added to the ends of eukaryotic chromosomes by telomerase
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Telomerase
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- active in germ cells and in bacteria - inactive in somatic cells - causes internal time clock |
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Progerias
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- disorders dealing with telomere length and aging in humans
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Hutchinson-Gilford Syndrome
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- aging symptoms begin immediately after birth (severe)
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Werner Syndrome
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- aging symptoms begin in teenage years (mild)
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