Chapter 6.3 Flashcards
Describe the difference between bacterial DNA replication and eukaryotic DNA replication
Bacterial DNA replication
- > bacterial chromosome is closed
- > double stranded circular DNA with a single origin of replication
- > therefore, there are two replication forks that move away from each other in opposite directions
- > the two forks eventually meet back and then split off, creating two identical circular molecules of DNA
Eukaryotic replication
- > must copy many more bases compared to prokaryotes
- > slower process
- > one linear(not closed) molecule of double stranded DNA
- > has MULTIPLE replication forks
- > as forks move toward each other, sister chromatids are created
- > chromatids will remain connected at the centromere
What is the purpose of single-stranded DNA-binding proteins
- they bind to unraveled DNA strands
- > prevent reassociation of these DNA strands with each other
- > also prevent them from being digested by nucleases
What is the purpose of DNA topoisomerase? Do they work ahead of the DNA helicase?
- it introduces negative supercoils
- > it reduces the torsional stress and reduces the risk of strand breakage
- they work ahead of the DNA helicase
- > nick one or both strands to allow relaxation
What is the leading strand in DNA replication?
- it is the strand in each replication fork
- > that is copied in a continuous fashion(away from the replication fork)
- > so that means from 5 prime to 3 prime
What is the lagging strand in DNA replication?
- it is the strand in each replication fork
- >that is copied in the direction opposite to the replication fork
What is the purpose of DNA polymerase 1 (prokaryotes) , RNase H(eukaryotes) and DNA polymerase δ(eukaryotes)?
- DNA polymerase 1 and RNase H remove RNA primers
- in those primers place, DNA polymerase 1 and DNA polymerase δ seal the ends with DNA molecules
What is the purpose of DNA polymerase alpha, δ, and ε?
-they work to synthesize the leading and lagging strands
What is the purpose of DNA polymerase gamma?
-it works to replicate mitochondrial DNA
What is the purpose of DNA polymerase beta and ε?
-they are important for the process of DNA repair
What is the purpose of DNA polymerase ε and δ?
-they work to strengthen the interaction between DNA polymerases and the template strand
