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10 Cards in this Set
- Front
- Back
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polymerization proceeds in which direction?
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in the 5' to 3' direction
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Ennzymes and proteins involved in DNA replication?
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primase: synthesizes a short RNA primer which provides a 3' OH group for DNA polymerases to begin synthesis
Helicase: separates DNA strands, allowing DNA polymerases access to single-stranded templates; requires ATP hydrolysis Single-stranded binding protein(SSBP): binds single-stranded DNA after helicase holds strands apart |
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Difference between DNA pol I and DNA pol III
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DNA
pol I: Function maturation of okazaki fragments pol III: leading and lagging strand synthesis polI polIII 5' to 3' polymerase yes yes 3' to 5' proof-reading yes yes 5' to 3' exonuclease yes no speed (nucleotide/sec) 10 1000 processivity low high pol I composition single pol III protein multi protein complex |
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What does DNA ligase do?
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It creates a phosphodiester bond between adjacent 5' phosphate and 3' OH. It seals the nick
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What are plasmids?
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small, circular DNA molecules that replicate independently of the bacterial host chromosome also have fixed origins of replications.
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Where does the replication bubble generally start?
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in AT rich regions because there are less hydrogen bonds
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when DNA replication proceeds bidirectionally from the origin of replication on a circular DNA molecule, it becomes overwound. What relieves this tension?
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topoisomerases
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Initiation of DNA replication: prokaryotes vs. Eukaryotes
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prokaryotes: small genomes with a single origin of replication
eukaryotes: nuclear genomes are extremely large with multiple origins of replication// replication of the ends of linear chromosomal DNA molecules = telomeres |
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What is the end replication problem?
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It predicts that linear chromosomal DNA will shorten with each round of DNA replication because there is no way to prime DNA synthesis at the very 5' end of the leading or lagging strand after removal of the RNA primer
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What is telomerase?
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a ribonucleoprotein (RNA+protein) complex that polymerizes a single-stranded 3' tension using an internal RNA template
It is a reverse transcriptase = RNA-directed DNA polymerase |
