DNA Replication Flashcards
What is the function of helicase?
It disrupts the hydrogen bonds between base pairs to “unzip” the DNA strands.
What is the function of primase?
Primase is an enzyme that creates a primer on a DNA strand by adding RNA nucleotides to the strand according to the DNA template sequence.
What is the function of DNA polymerase?
DNA polymerase adds base pairs to the growing new strand of DNA during replication.
What is function of ligase?
Ligase seals the nicks in the DNA’s phosphate backbone of the lagging strand.
As the replication fork continues to open, one strand can be continously synthesized (leading strand), but the other cannot. Is the lagging strand 3’ to 5’ or 5’ to 3’? What about the leading strand?
The leading strand is synthesized from 3’ to 5’ and the lagging strand is synthesized from 5’ to 3’.
How does DNA mismatch repair know that the wrong DNA nucleotide has been added to the DNA strand?
There is a defomity in the DNA molecule at the site where the wrong nucleotide has been added.
Name two reasons why every DNA mutation is not necessarily harmful.
Denegeracy of the genetic code - each amino acid can be coded for by several codon sequences
The wobble effect of tRNA - the last base pair of a codon can vary and still result in the right tRNA molecule binding there because it binds most loosely with the last nucleotide base. Therefore, if the last base pair of a mRNA segment is wrong, there is a chance that the right tRNA molecule will still be added at its correct place in the sequence.
How is it that cell lines obtain ploidy levels greater than 4 (tetraploid)?
Cytokinesis never occurs after mitosis, therefore, the resulting cell contains multiple nuclei, but exists as a singular cell.
