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39 Cards in this Set

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  • Back
what are the 2 enzymes that accomplish supercoiling of the bacterial genome
DNA gyrase

DNA topoisomerase I
what are the proteins at the center of the supercoiled, radially arranged bacterial nucleoid
HU proteins
in prokaryotes what enzymes repair supercoiling that occurs in transcribing DNA
DNA gyrase

Topoisomerase I
how does Topoisomerase I work?
breaks ONE phosphodiester bond to let the strand spin
how does Topoisomerase II work?
The Untangler

covalently links, makes a double strand break, passes the 2nd strand through, reseals the break
what do you call the complex of DNA and chromosomal proteins
what are the four core proteins of histones and the one that binds histones together
core: H2A, H2B, H3, H4

how wide is the beads on a string' extended form of chromatin
11 nm
when the H1 proteins are associating how wide is the 'solenoid fiber'

is this considered euchromatin
30 nm

oh yeah
what process really subtends the formation of heterochromatin
the methylation of cytosine on C5

to 5-methyl-cytosine

by DNA methyltransferase enzyme
methylation of both strands' cytosine residues initiates what sequence of events
the strand is bound by MethylCytosine Binding Proteins, which recruit OTHER PROTEINS (HDAC 1/2) that remove acetyl groups from lysine residues in the histones

this leaves a positively charged N+ hanging out on the lysine residue which causes it to associate more tightly with the negatively charged nucleic acids
are there histones in sperm?
apparently not

they use something called protamines that holds DNA even tighter
how much of chromatin is histones
about half
what enzyme is responsible for DNA chain elongation in prokaryotes and where does the energy come from
DNA Polymerase

from the deoxynucleoside 5' triphosphate
what direction does DNA polymerase go, and what does it add the new nucleoside to
5' to 3'

adds it to the 3' hydroxyl group
remember Acyclovir? what is it lacking that makes it a chain terminator
it has an open chain structure where the sugar should be

(targets viral enzymes)
Vidarabine and Cytarabine do what?
cytosine arabinoside

adenosine arabinoside

they have that planar configuration that makes their 3' -OH groups useless
which enzyme has the 3' to 5' proofreading, chews the nucleosides back until they're right and rebuilds the strand correctly
DNA polymerase
what enzyme binds to the origin of replication and breaks H bonds between bases
Initiator proteins (DNaA protein
what opens the helix and binds primase to form a primasome
DNA helicase (DNaB)
what delivers helicase to the DNA template
Helicase inhibitor (DNaC)
what do you call the RNA polymerase that synthesizes a RNA primer on the lagging strand to enable DNA polymerase to go to work
DNA primase
who's job is it to remove the RNA primer and replace it with DNA
DNA polymerase
what synthesizes the leading and lagging strands
DNA polymerase (prokaryotes)
what binds to single stranded DNA in the replication bubble to prevent it from reannealing or forming secondary structure
Single stranded binding protein (ssb)
what do you expect to see in the DNA sequences of Origins of Replication
a whole lot of A-T bonding (2 H bonds)
what enzyme joins the Okazaki fragments
DNA ligase
what holds the DNA polymerase onto the template and releases it when it gets to a double stranded region
clamp protein
in prokaryotes, what enzyme introduces negative supercoiling into the DNA
DNA gyrase
what antibiotic inhibits bacterial DNA gyrase

it's a quinalone
useful for respiratory, urinary tract infections
and anthrax
what enzyme fills the gaps at the telomeres resulting from the removal of the RNA primer
what's the novel thing about Telomerase
its reverse transcriptase character

synthesizes DNA using an RNA template, carries its own RNA primer
In prokaryotes, DNA polymerase I removes and replaces the RNA primer. What enzyme does this in eukaryotes?

Synthesizes the RNA primer on both leading and lagging strands

Has a subunit with primase activity that initiates DNA synthesis
In prokaryotes DNA polymerase III synthesizes the leading and lagging strands. What enzyme does this in eukaryotes?
Polymerase - delta

Synthesizes the leading and lagging strands with high processivity (long strands)

handles the 3' -5' proofreading activity

anti-cancer drugs that inhibit the religase activity following Topoisomerase activity, stopping DNA replication

Camptothecin- topoisomerase I
Etoposide- topoisomerase II
Actinomycin d
anti-cancer agent

Actinomycin binds tightly to double stranded DNA and inhibits both replication and transcription
what does the quinalone family of drugs do
the quinalones inhibit DNA gyrase

DNA replication is halted due to buildup of positive supercoiling
what does Camptothecin DO?
specifically, camptothecin prevents the religation of DNA after the cleavage activity of Topoisomerase I
What's Etoposide do, like specifically
Etoposide interferes with the religation following the activity of Topoisomerase II