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37 Cards in this Set
- Front
- Back
- 3rd side (hint)
in DNA replication, nucleotides are added to which end of the DNA molecule? |
3' end
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the addition of a nucleotide to a growing DNA molecule is made energetically favorable how?
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hydrolysis of pyrophosphate
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None
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what is meant by semi-conservative DNA replication?
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resulting DNA has one parent strand and one daughter strand
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DNA polymerases require which 3 things?
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nucleotides, template, primer
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how many origins of replication are present in bacterial DNA replication? Human DNA replication?
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one; many
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what are the names of the 3 phosphates, in order of proximity to ribose sugar? |
alpha, beta, gamma
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what is the destiny of the pyrophosphate molecule? This is catalyzed by which enzyme? |
broken down into 2 inorganic phosphate molecules; pyrophosphatase |
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DNA replication begins with the binding of which protein to the origin of replication to unwind DNA? Does this process require energy? |
DnaA; yes, ATP
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what happens following DnaA binding and unwinding at origin of replication? Is energy used in this process? |
helicase binds to unwound DNA at origin and separates DNA strands; yes, ATP
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which proteins are responsible for keeping separated DNA strands apart?
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single-stranded binding proteins (SSB)
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which protein is responsible for creating a RNA primer for the start of DNA replication? In what class is this protein? |
primase; RNA polymerases
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other than the obvious, what is a large difference between RNA and DNA polymerases? |
RNA polymerase can create a polynucleotide de novo |
None
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what is meant to say DNA polymerases are processive?
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they carry out multiple rounds of nucleotide addidion and do not fall off template until they reach the end or are actively unloaded.
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processivity of DNA polymerase is conferred by which subunit?
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beta
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what is the name for the fragments which compose the lagging strand in DNA replication?
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Okasaski fragments
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is DNA polymerase which synthesizes lagging strand always bound? |
no, it binds once DNA is sufficiently unwound for the formation of a new fragment.
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which DNA polymerase is responsible for enlongating DNA from RNA primer?
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DNA polymerase III
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which DNA polymerase is responsible for removing the RNA primer at the beginning of each Okasaki fragment?
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DNA polymerase I
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which DNA polymerase is responsible for replacing RNA primer with DNA?
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DNA polymerase I
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which DNA polymerase, I or III, is faster at enlongating polynucleotide chain?
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DNA polmerase III
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which enzyme is responsible for sealing the nick remaining between two Okasaki fragments?
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DNA ligase
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None
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which property of DNA ligase prevents it from ligating Okasaki fragments prematurely (before RNA is removed)?
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it can only ligate together two DNA molecules
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what is the function of topoisomerase? How is this done?
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to release tension on DNA molecule as it becomes unwound; by nicking one strand of DNA, passing the other strang through the nick, and resealing the nick. |
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most errors in DNA replication are due to what?
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the fact that a base was incorporated while in its tautomeric configuration
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1 out of every how many bases laid by DNA polymerase is incorrect? |
10,000
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which DNA polymerase is capable of 3' to 5' exonuclease activity?
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both I and III
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what is the name for the ends of chromosomes?
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telomeres
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what is the function of telomeres?
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to protect the ends of chromosomes
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what is the name of the enzyme responsible for adding telomeres?
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telomerase
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telomerase elongates which strand of DNA from its 3' end?
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lagging strand
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which kind of nucleotides are added by telomerase?
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RNA
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during which phase of life, embryonic or adult, are telomeres longer? Why?
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embryonic; most adult somatic cells lack telomerase activity.
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what happens as telomeres shorten?
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chromosomes tend to become fused together via their ends, leading to a higher rate of chromosome loss
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what effect does overexpression of telomerase in cancer cells have? |
it renders the cancer cells immortal
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what is the name of the disease associated with a shortage of telomerase activity? |
Dyskeratosis congenita
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what is the name for the family of enzymes that can make DNA from an RNA template? |
Reverse transcriptases
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why are reverse transcriptases highly error prone?
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they lack 3' to 5' exonuclease activity
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