chapter 12 Flashcards
which description about prokaryotic versus eukaryotic DNA replication is not correct ?
in prokaryotes, the DNA is unidirectional: in eukaryotes, the replication is bidirectional
which statement describes the semi conservative model of DNA correctly?
it proposes that the two nucleotide strands unwind and each served as a template for a new DNA molecule
what property of the DNA molecule explains the necessity for okazaki fragments ?
DNA is anti parallel
which component required for prokaryotic DNA replication is not involved in unwinding the DNA template?
DNA ligase
which enzyme is responsible for the replication of chromosome ends in germ cells and certain proliferating somatic cells ?
telomerase
which statement is true of DNA replication?
the lagging strand is composed of okazaki fragments
as DNA is replicated, both continuous and discontinuous replication occur. discontinuous replication is the result of which specific feature of DNA?
antiparallel strands
order of DNA replication
- Helicase unwinds the DNA double helix
- Single-stranded DNA-binding proteins bind to each template strand
- RNA primers are added
- DNA polymerase syntheiszes DNA
- RNA primer are removed
- DNA ligase joins DNA fragments together
which result did meson and stahl observe by sedimentation equilibrium centrifugation to provide strong evidence for the semiconservative model of DNA replication?
the first generation has hybrid 15N/14N DNA and the second generation has both hybrid 15N/14N DNA and 14N/14N DNA. No 15N/15N DNA was observed
what will be the distribution of radioactivity in the DNA of the bacteria in each sample?
immediately after the transfer: no 32P incorporated into the DNA
after one round of replication: one strand has 32P incorporated
after two rounds of replication: 50% of the DNA molecules have 32P in both strands and 50% of the DNA molecules have 32P in one strand
match the protein to its role in DNA replication
DNA topoisomerase relaxes the supercoiled DNA
helicase unwinds the DNA double helix
SSB protein prevents the reannealing of DNA strands
DNA polymerase I replaces RNA primers with DNA
primase synthesizes RNA primers
steps of eukaryotic DNA replication
cell enters gap 1
pre-replication complex forms at one of many origins of replication
the initiation complex create an active replication fork as helices unwinds DNA
RNA primers are added to provide a 3’ end for elongation
DNA polymerase synthesizes both the leading and lagging strands from 5’ to 3’
RNA is replaced with DNA and lagging strands are joined
active telomerase can extend the lost telomere region
which does DNA polymerization by DNA polymerase require?
a 3’ hydroxyl group on the growing strand
match the consequence of a loss-of-function mutation in DNA polymerase I to the corresponding lost activity
lost 5’-3’ polymerase activity: no DNA synthesis to fill gaps caused by removing RNA primers
lost 5’-3’ exonuclease activity: no RNA primer removal during DNA replication
lost 3’-5’ exonuclease activity: decreased polymerase fidelity
which statements best explain why the end-replication problem exists in eukaryotic chromosomes ?
DNA polymerase requires a primer for DNA synthesis
DNA polymerase synthesizes DNA from the phosphate end to the hydroxyl end
