DNA Replication Lesson Review Flashcards
What did Watson and Crick’s model of DNA structure suggest how DNA can be replicated?
- hydrogen bonds between nitrogenous bases break
- helix unzips
- each strand acts as a template to build new strand
What did Meselson and Stahl’s expirement conclude about DNA replication?
It concluded that DNA replication is not conservative but semi-conservative. Each DNA strand is composed of one parent strand.
Where does Replication Begin?
It begins when proteins bind to the replication origin sites of DNA.
- Hydrogen bonds holding them together must break.
- Specific enzymes work to pull apart the DNA template strands and to keep them separate and untangled.
Which DNA polymerase is Utilized in Prokaryotes for the building of complementary strands?
DNA polymerase I, II, and III get utilized within Prokaryotes. There are 5 different types of DNA polymerase that are utilized within eukaryotes.
What is required when a DNA polymerase is initiating a new strand?
It requires an RNA primer to initiate a new strand of DNA polymerase.
What does the enzyme Helicase do in DNA Replication?
It breaks the hydrogen bonds holding the two complementary parent stands together. Which results in an unwound, unzipped helix that terminates at the replication fork.
What is SSBs?
It stands for Single-Stranded Binding Proteins.
What does Anneal (bind) do in DNA Replication?
It binds to the newly exposed template strands. This prevents them from re-bonding by blocking hydrogen bonding.
Where is Gyrase found and what does it do?
It is found in Bacteria and Plants. It RELIEVES any TENSION from the UNWINDING of the DOUBLE HELIX. It does this by Cutting Both strands of DNA and allowing them to Swivel around one another., then Resealing them.
What does the Primase do in DNA Replication?
The Primase enzyme lays down RNA primers that is used by DNA polymerase to build new complementary strands.
Which Two Directions does DNA Replication begin at?
- Toward direction of replication fork on one strand.
- Away from the direction of replication fork on the other.
Can more than one replication fork exist at once within a eukaryotic cell?
Yes, because there are many sites of origin.
Why does the New Synthesized DNA 5’ to 3’?
This is because the two template strands are anti-parallel, only one strand is able to be built continuously.
Which strand is Build Continuously and Toward the replication fork?
The Leading Strand is built continuously towards the replication fork.
Which strand is Synthesized Discontinuously Away from the replication fork?
The Lagging Strand is synthesized discontinuously away from the replication fork.
What Enzyme are Continuously added as the Replication Fork Forms?
Primers are continuously added.
What are the short segments of DNA that polymerase gets built in DNA is called?
The short segments of DNA are known as Okazaki Fragments.
What gets Removed in Eukaryotes Cells and how?
Rnase H removes the RNA primers, however in prokaryotes it is done by one of the DNA Polymerases.
What joins the gaps in the Okazaki Fragments by the creation of a Phosphodiester Bond?
DNA Ligases joins gaps in the Okazakia Fragments.
What does DNA Polymerases do and how?
DNA Polymerases proofread the replicating strands. It is done by acting as a exonuclease.
How can errors that are missed be corrected and when?
They can only get corrected after the DNA Replication and by other repair mechanisms.
