Terms in this set (56)
Consider the process that a cell uses to replicate its double-stranded DNA before undergoing cell division. Which statement describes the DNA in the resulting daughter cells?
The double helices in each daughter cell consist of one parental strand and one newly synthesized strand.
Which term best describes DNA replication?
What kinds of bonds link the two strands of a double helix to each other?
DNA synthesis begins at:
Replication origins typically consist of a small stretch of duplex DNA that is relatively easy to pry apart. Which statement is true?
Replication origins are rich in A and T nucleotides.
The two replication forks that form at an origin of replication move:
in opposite directions.
DNA synthesis proceeds:
in the 5'-to the-3' direction.
Nucleotides are linked by:
The energy for DNA polymerization is provided by the hydrolysis of:
incoming nucleoside triphosphates (releasing PPi)
A newly synthesized DNA strand of a human chromosome:
is produced by a mixture of continuous and discontinuous DNA synthesis from multiple replication origins.
Experimental evidence supporting the semiconservative nature of DNA replication came from:
centrifugation of DNA purified from E. coli grown in a radioactive medium.
In a DNA double helix, which strand will serve as the template during replication?
Both strands will serve as templates during replication.
If DNA replication were conservative, what would Meselson and Stahl have seen following the first round of replication in E. coli that had been switched from a heavy, 15N-containing nutrient medium to a light, 14N-containing one?
Half the DNA would be heavy, half would be light.
The nucleotide sequence of one DNA strand in a DNA double helix is 5'-CATTGCCAGAAAAAT-3'. Which is the sequence of the complementary strand produced during replication?
When read in the same 5'-to-3' direction, the sequence of nucleotides in a newly synthesized DNA strand is the same as in the template strand used for its replication.
If an origin of replication is removed from a eukaryotic chromosome, the DNA on either side will also be lost as it cannot be replicated.
At a replication fork, both strands of DNA are replicated in the 5'-to-3' direction.
At a replication fork, the leading strand is synthesized:
At a replication fork, the lagging strand is synthesized:
Approximately how often does DNA polymerase make an error during DNA replication?
Once per 10,000,000 nucleotides added to the growing DNA chain
When does DNA polymerase perform its editing function on incorrectly incorporated nucleotides?
Before adding the next nucleotide in the chain
The error-correcting proofreading activity of DNA polymerase occurs in which direction?
3' to 5'
During DNA replication, DNA polymerase initiates a completely new DNA strand from scratch.
Which of the following describes a primer used in DNA replication?
A short segment of RNA, about 10 nucleotides in length
DNA replication requires only two primers: one for the lagging stand and one for the leading strand.
What powers the action of helicase at the replication fork, where it opens up the double helix?
What is the function of single-strand binding proteins in DNA replication?
They bind to regions of single-stranded DNA, preventing them from forming base pairs.
During replication, the sliding clamp:
keeps DNA polymerase attached to the template while it synthesizes a new strand of DNA.
The enzyme that replicates the ends of linear chromosomes is called:
What happens after the DNA polymerase on the lagging-strand template completes an Okazaki fragment?
The sliding clamp attached to the polymerase dissociates from the DNA and the polymerase temporarily releases the lagging-strand template
In the absence of telomerase, eukaryotic chromosomes lose a bit of DNA from their ends during each round of cell division. Based on your understanding of DNA replication, which statement best describes the daughter chromosomes in a eukaryotic cell after one round of replication in the absence of telomerase?
Both daughter chromosomes will have a gap at only one end.
A single DNA strand can serve as a template for both leading and lagging DNA strands.
The production of a continuous new strand of DNA from the many separate Okazaki fragments made on the lagging strand does NOT require:
Which is NOT part of the replication machine?
What does depurination refer to?
The loss of A or G bases from DNA
How does ultraviolet radiation in sunlight typically damage DNA?
It causes two adjacent pyrimidine bases to become covalently linked.
What type of enzyme removes damaged DNA from the rest of the DNA molecule?
What type of enzyme fills in the gap after damaged DNA has been removed?
What type of enzyme seals the newly added (repaired) DNA to the rest of the DNA molecule?
Copying errors that slip by the replication machinery can be corrected by:
the DNA mismatch repair system.
DNA mismatch repair can correct what percentage of replication errors?
Most cancers arise from cells that have accumulated multiple mutations.
When a cell repairs a double-strand DNA break by the process of nonhomologous end joining:
the DNA sequence at the site of repair has been altered by a short deletion.
Double-strand breaks can be repaired flawlessly by:
In addition to its role in DNA repair, homologous recombination is also responsible for generating genetic diversity during what process?
Homologous recombination occurs only between DNA molecules that are identical in nucleotide sequence.
Homologous recombination occurs only in eukaryotes.
Mutations that change a single nucleotide in a gene have deleterious effects on the protein encoded by that gene:
Mutations to the genome that have harmful consequences to an organism:
are usually eliminated from the population by natural selection.
The flawless repair of double-strand DNA breaks by homologous recombination is most likely to occur:
after the cell's DNA has been replicated.
The loss of purine bases from a strand of DNA is typically caused by:
spontaneous chemical reaction.
Mutations are NOT caused by
A mutation is:
a permanent change in a DNA sequence.
No two cells in your body have the identical nucleotide sequence.
Most likely true
Like eukaryotic cells, bacteria also make approximately one error for every 109 nucleotides copied. In a culture flask that contains 106 E. coli cells, how many cells, on average, would carry a mutation in a particular gene after the population doubles? Assume that the gene is 1000 nucleotide pairs in length and is not essential for bacterial growth or survival.
The mismatch repair system recognizes mismatched base pairs, removes a portion of the DNA strand containing the error, and then resynthesizes the missing DNA using the correct sequence as a template. But what if the mismatch repair system instead removed a piece of the DNA strand that contained the correct sequence? Replication of this improperly repaired sequence would produce:
two DNA molecules bearing the same mutation.
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