DNA Replication (The Details) Flashcards
What are the two main steps in DNA replication?
Seperating the two strands of nucleotides
Building the new strands of DNA
Originally there were 3 theories for how DNA replicated. Which of these theories was proven to be accurate?
Semiconservative Replication
What breaks the hydrogen bonds between the two strands of nucleotides?
The DNA helicase
After the DNA Helicase separates the hydrogen bonds, what prevents them from rejoining?
The Single Stranded Binding proteins
What is the site called that the DNA helicase binds to in order to start DNA replication?
The replication origin
What is the function of DNA gyrase?
DNA Gyrase reduces the tension that builds up when DNA is unwinding.
What allows eukaryotes to replicate their DNA in a timely manner?
Eukaryotes contain multiple points of origin
Describe the role of RNA primase and the role of the RNA primer.
RNA primase lays down RNA nucleotides complimentary to the 3’ end of the DNA. This primer is necessary for DNA polymerase III to begin laying down DNA nucleotides.
Why is there a leading and lagging strand in replication
DNA is antiparallel in its structure resulting in a 5’ to 3’ strand and a 3’ to 5’ strand. RNA primer and DNA Polymerase III can only add nucleotides in the 5’ to 3’ direction.
What are Okazaki fragments?
Sections of replicated DNA on the lagging strand.
Describe the role of DNA polymerase I
Replaces the RNA primer with DNA nucleotides
Describe the role of DNA ligase
After the RNA primer is removed, Ligase reforms the phosphodiester bonds between nucleotides
How are errors in replication corrected
DNA poly III can “back up” if there is an incorrect base pair. DNA poly II moves behind checking for errors. DNA poly I replaces incorrect nucleotides with the correct one
There is a significant problem as replication finishes on the lagging strand. What is it?
The final RNA primer cannot be replaced with DNA nucleotides and as a result the final section of DNA is lost/cut off.
What role do telomeres play in DNA replication?
Telomeres are junk DNA (non-coding) located at the ends of our chromosomes. They ensure that useful (coding) DNA is not cut off at the end of replication.
