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39 Cards in this Set
- Front
- Back
what are the 2 enzymes that accomplish supercoiling of the bacterial genome
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DNA gyrase
DNA topoisomerase I |
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what are the proteins at the center of the supercoiled, radially arranged bacterial nucleoid
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HU proteins
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in prokaryotes what enzymes repair supercoiling that occurs in transcribing DNA
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DNA gyrase
Topoisomerase I |
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how does Topoisomerase I work?
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breaks ONE phosphodiester bond to let the strand spin
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how does Topoisomerase II work?
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The Untangler
covalently links, makes a double strand break, passes the 2nd strand through, reseals the break |
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what do you call the complex of DNA and chromosomal proteins
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chromatin
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what are the four core proteins of histones and the one that binds histones together
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core: H2A, H2B, H3, H4
H1 |
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how wide is the beads on a string' extended form of chromatin
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11 nm
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when the H1 proteins are associating how wide is the 'solenoid fiber'
is this considered euchromatin |
30 nm
oh yeah |
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what process really subtends the formation of heterochromatin
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the methylation of cytosine on C5
to 5-methyl-cytosine by DNA methyltransferase enzyme |
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methylation of both strands' cytosine residues initiates what sequence of events
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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 |
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are there histones in sperm?
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apparently not
they use something called protamines that holds DNA even tighter |
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how much of chromatin is histones
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about half
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what enzyme is responsible for DNA chain elongation in prokaryotes and where does the energy come from
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DNA Polymerase
from the deoxynucleoside 5' triphosphate |
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what direction does DNA polymerase go, and what does it add the new nucleoside to
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5' to 3'
adds it to the 3' hydroxyl group |
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remember Acyclovir? what is it lacking that makes it a chain terminator
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it has an open chain structure where the sugar should be
(targets viral enzymes) |
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Vidarabine and Cytarabine do what?
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cytosine arabinoside
adenosine arabinoside they have that planar configuration that makes their 3' -OH groups useless |
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which enzyme has the 3' to 5' proofreading, chews the nucleosides back until they're right and rebuilds the strand correctly
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DNA polymerase
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what enzyme binds to the origin of replication and breaks H bonds between bases
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Initiator proteins (DNaA protein
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what opens the helix and binds primase to form a primasome
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DNA helicase (DNaB)
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what delivers helicase to the DNA template
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Helicase inhibitor (DNaC)
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what do you call the RNA polymerase that synthesizes a RNA primer on the lagging strand to enable DNA polymerase to go to work
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DNA primase
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who's job is it to remove the RNA primer and replace it with DNA
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DNA polymerase
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what synthesizes the leading and lagging strands
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DNA polymerase (prokaryotes)
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what binds to single stranded DNA in the replication bubble to prevent it from reannealing or forming secondary structure
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Single stranded binding protein (ssb)
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what do you expect to see in the DNA sequences of Origins of Replication
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a whole lot of A-T bonding (2 H bonds)
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what enzyme joins the Okazaki fragments
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DNA ligase
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what holds the DNA polymerase onto the template and releases it when it gets to a double stranded region
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clamp protein
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in prokaryotes, what enzyme introduces negative supercoiling into the DNA
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DNA gyrase
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what antibiotic inhibits bacterial DNA gyrase
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Ciprofloxacin
it's a quinalone useful for respiratory, urinary tract infections and anthrax |
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what enzyme fills the gaps at the telomeres resulting from the removal of the RNA primer
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Telomerase
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what's the novel thing about Telomerase
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its reverse transcriptase character
synthesizes DNA using an RNA template, carries its own RNA primer |
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In prokaryotes, DNA polymerase I removes and replaces the RNA primer. What enzyme does this in eukaryotes?
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Polymerase-alpha
Synthesizes the RNA primer on both leading and lagging strands Has a subunit with primase activity that initiates DNA synthesis |
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In prokaryotes DNA polymerase III synthesizes the leading and lagging strands. What enzyme does this in eukaryotes?
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Polymerase - delta
Synthesizes the leading and lagging strands with high processivity (long strands) handles the 3' -5' proofreading activity |
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Camptothecin
Etoposide |
anti-cancer drugs that inhibit the religase activity following Topoisomerase activity, stopping DNA replication
Camptothecin- topoisomerase I Etoposide- topoisomerase II |
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Actinomycin d
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anti-cancer agent
Actinomycin binds tightly to double stranded DNA and inhibits both replication and transcription |
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what does the quinalone family of drugs do
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the quinalones inhibit DNA gyrase
DNA replication is halted due to buildup of positive supercoiling |
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what does Camptothecin DO?
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specifically, camptothecin prevents the religation of DNA after the cleavage activity of Topoisomerase I
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What's Etoposide do, like specifically
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Etoposide interferes with the religation following the activity of Topoisomerase II
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