10 Flashcards
DNA helicase
unwinds the DNA strands
The unwinding of DNA strands causes a Y shaped structure called
replication fork
single stranded binding proteins
coat the exposed single DNA strands , keeping the two strands from pairing back together
topoisimerase
An enzyme that stops the DNA strands from twisting any more so that they can rejoin
why is RNA primer used to begin a new strand
Because DNA polymerase can only add nucleotides to the 3’ end of an existing strand
what does DNA polymerase III do
what about polymerase I
- extends the primer by adding nucleotides
- used for the lagging strand, it removes RNA nucleotides and replaces them with DNA nucleotides
The DNA of prokaryotic organisms differ from eukaryotic organisms because
Pro DNA is rarely packaged in linear chromosomes
Hershey and Chase used ________ to radioactively label DNA in T2 phages.
32^P
The experiments of ________ showed that a bacterial phage labeled with 35S did not enter the bacteria, eliminating protein as the hereditary material.
Hershey and Chase
Watson and Crick discovered that genetic information must be coded in the ________ of DNA.
Sequence of nitrogenous bases
In DNA replication, if the old strand reads in the 5’-3’ direction, the new strand is formed in the ________ direction.
antiparallel
Okazaki fragments are synthesized on ________
the lagging strand
DNA polymerase removes the RNA primer, replacing it with DNA, leaving a nick between the Okazaki fragments. Which enzyme seals the nicks?
DNA ligase
In DNA replication, which enzyme can correct mismatched nucleotides and perform repair?
DNA polymerase
Eukaryotic DNA is most tightly condensed into chromosomes complexed with which protein?
histones
