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35 Cards in this Set

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  • Back
What are the names of the histone proteins? (5)
What is the charge of histone proteins, why is this important?
They are positively charged. Most proteins are negatively charged
Which two amino acids carry positive charges?
Why is this significant?
Arginine and Lysine
Histone proteins are thus made of an abundance of arginine and lysine amino acids
what is a nucleosome?
DNA donut composed of histone proteins at the core with a DNA "shoelace" surrounding the histone proteins
How many histones are found in a nucleosome and what are these histones?
There are 8 total histones in the nucleosome. There are two copies of H2A, H2B, H3, and H4
What happens to DNA missing hte H1 protein?
That DNA is sensitive to nucleases
What is the width of DNA without H1?
it is refered to as the "10nm FIBER"
What is DNA packaged with proteins known as?
What is chromatin with a 10nm width known as?
euchromatin, also loosely packaged chromatin
What is significant about euchromatin?
it is sensitive to nucleases and lacking the H1 histone
What is the role of H1?
it condenses the nucleosomes tightly together
What is chromatin with H1 known as?
What is the significance of heterochromatin?
it is not sensitive to nucleases
What is the width of heterochromatin?
30 nm
Where in the DNA is replication started?
Specific sequence known as the origin of replication
What is the initial produce of DNA replication in a eukaryote?
Sister chromatids
Where are the sister chromatids connected?
What is required for DNA polymerase to start DNA replication?
RNA primer
When a mismatch of a base is made during the DNA replication, what is needed to correct this problem?
3' Exonuclease
What molecule actually performs the 3'exoclease?
3' exonuclease is a property of all DNA polymerases
What is used to make an RNA strand and how is this different from the replicatoin of DNA?
RNA polymerase is needed and this is different from the DNA replicatoin because RNA polymerase does not need an RNA primer
Compare the proofreading of DNA vs. RNA?
DNA replication is a HIGH-FIDELITY process and thus mismatched bases are corrected, while RNA synthesis is a LOW FIDELITY process and thus mismatched bases are not corrected
What molecule recognized the origin of replication in bacteria?
DNA A protein
What molecule denatures the DNA to expose the bases for replication in bacteria?
In bacteria, what inhibits the single strands from recombining after they have been separated by helicase?
Single strand binding proteins
What are the two functions of SSBs?
To inhibit the parent strand from reannealing and the protect the single strand DNA from nuclease enzymes
After the strands have been separated and stabilized, what happens before DNA replication can take place and what molecule causes this?
PRIMASE (RNA polymerase) must first add the RNA primer the the DNA polymerase to continue from
What is the DNA polymerase, in bacteria, that does most of the DNA replication
DNA polymerase 3
What is the name of the fragments of DNA synethesized on the lagging strand?
Okazaki Fragments
In bacteria, after the DNA has been reeplicated, what are the final modification made to the newly synthesized strand?
DNA polymerase 1's 5' Exonuclease activity will remove the RNA primers and, because it is a DNA polymerase it will replace the RNA with DNA.

After the RNA has been replaced with DNA the DNA segments must be connected. This is done by DNA ligase
What are the differences between replication in prokaryotic vs. eukaryotic cells
DNA A protein recognizes origin of replication.

Eukaryotes: unknown recognition of origin of replication

Synthesis of DNA -
DNA polymerase III does both the leading and lagging strand

Leading strand - DNA polymerase delta
Lagging strand - DNA polymerase alpha

Removal of RNA primers:
Prokaryote - DNA polymerase I (5'exonuclease)
Eukaryote - Unknown

Replacement of RNA with DNA:
Prokaryote - DNA polymerase I
Eukaryote - Unknown

Synthesis of telomeres:
Prokaryotes - Not necessary because there are no telemeres
Eukaryotes - Telomerase
What enzyme removes the positive supercoils ahead of advanceing replication forks?
DNA topoisomerase II
What is the difference between DNA ligase in prokaryotes and eukaryotes?
In prokaryotes, DNA ligase requires NAD. In eukaryotes, DNA ligase requires ATP.
In prokaryotes, what is DNA topoisomerase II often known as?
DNA gyrase
What antibiotics inhibit DNA gyrase?
quinolones and fluoroquinolones