Chapter 9 Questions Flashcards
(10 cards)
What band is predicted in the semiconservative replication model?
A single band of intermediate density.
What are the requirements of replication?
A template consisting of a single stranded DNA, substrates to be assembled into a new nucleotide strand, and enzyme and other proteins that “read” the template and assemble the substrates into a DNA molecule.
What is initiation in replication of E. coli?
DnaA bind to oriC and cause a short section of DNA to unwind. This allows helicase to attach.
Where are primers synthesized on the lagging strand?
At the beginning of every okazaki fragment.
What activity does DNA polymerase III not have that polymerase I does?
5’ to 3’ exonuclease activity.
What does DNA polymerase I do?
It follows DNA polymerase III and uses its 5’ to 3’ exonuclease activity to remove the RNA primers and uses its 5’ to 3’ polymerase activity to replace the RNA with DNA.
How can DNA polymerase III replication 2 strands at the same time even though they run in opposite directions?
2 DNA polymerases are present at each replication fork. They are connected, so the lagging strand loops around so that it is in the 5’ to 3’ direction.
What is the termination protein?
Tus-Ter complex. It blocked the replication fork moving one direction, but not the other.
What is the end replication problem?
When the terminal primer at the end of the chromosome has been removed, it cannot be replaced by DNA nucleotides, so it removal leaves a gap at the end of the chromosome, suggesting that the chromosome should become shorter with each replication.
How is the telomere extended?
By telomerase, an enzyme with both a protein and an RNA component.
