Ch 12 Adaptive Quiz: DNA Replication and Recombination

At which location(s) on the leading strand of a replication fork are primers synthesized?

only at 5’ end of the newly synthesized strand

Eukaryotic DNA replication is different from prokaryotic replication in all of these ways EXCEPT

eukaryotic DNA is made up of different bases than prokaryotic DNA

Which mechanism is used to resolve Holliday junctions following recombination?

cleavage and reunion

Meier–Gorlin syndrome is characterized by defective origin-replication complexes. Why does a mutated origin-replication complex result in slow cell division and growth?

origins are not appropriately licensed for replication

The diagram illustrates _______ replication, which is characteristic of some viruses and the F factor of E. coli

rolling-circle

A scientist examining the products of meiosis in a particular fungus with the genotype Aa noticed that occasionally the products occur in the ratios 3 A:1 a or 3 a:1 A. This results from

gene conversion

Which activity of DNA polymerases in E. coli allows them to remove a nucleotide that has been inserted incorrectly?

3' to 5' exonuclease

A single-celled human zygote contains approximately 6.0 billion base pairs of DNA. E. coli cells replicate at a rate of 1000 bases per second. If eukaryotic cells could replicate at the same speed as E. coli, how long would it take for the DNA in a human zygote to be copied?

100,000 minutes

Expression of a particular mutation in E. coli causes half of newly synthesized DNA to persist as fairly short fragments. The mutation most likely affects a gene that encodes DNA

ligase

Which feature is not affected in someone with Meier–Gorlin syndrome?

intellectual ability

Which proposed model of replication is illustrated in the diagram

dispersive

Which of these is NOT involved in the unwinding process of replication in E. coli?

initiator proteins

Which proposed model of replication would produce the results shown from a Meselson-Stahl experiment?

dispersive

The diagram illustrates replication of which of these?

an eukaryotic chromosome

What characteristic of DNA molecules allows for homologous recombination without the gain or loss of any genetic material?

complementary base pairing

Primers are synthesized where on the lagging strand of a replication fork?

at the beginning of every Okazaki fragment

Although replication machinery is extremely precise, mistakes still happen occasionally. What happens in the cell when a replication mistake occurs?

repair mechanisms identify and fix the mistake

What would happen if eukaryotic cells did not go through licensing in the process of replication?

some genes would not be replicated while others would be replicated more than once

During mitosis, DNA is replicated and separated into identical daughter cells. Recombination does not result in new allele combinations, as any exchanged genes are identical. What is the benefit of recombination between identical chromosomes?

repair mismatches and strand breaks by replacing mismatches or missing bases with DNA copied from the original undamaged sequence

Meier-Gorlin syndrome results from a flaw in which function?

DNA replication

Crossing over during meiosis could theoretically occur before, during, or after DNA synthesis. Evidence indicates that crossing over takes place in prophase I. What does this evidence suggest about possible mechanisms of recombination?

Crossing over must occur when chromosomes are at the four-strand stage

The bacterial chromosome shown is undergoing _____ replication.

theta

In a typical yeast cell, how many autonomously replicating sequences would there be?

one per chromosome

What halts the replication machinery and prevents the proliferation of cancer cells following camptothecin use?

accumulating supercoils

Individuals with Meier–Gorlin syndrome demonstrate reduced cell division and slower growth. Consider a genetic condition in which the origin-replication complex becomes hyperactive instead of less functional. What symptoms would you expect to see in affected individuals?

uncontrolled cell growth and tumor formatino

Homologous recombination is beneficial for multiple reasons, EXCEPT that

it decreases the rate of mutation

How would a mutation in the gene for DNA helicase affect replication?

the double-stranded DNA molecule would not be unwound

Following initiation of DNA replication in E. coli, DNA _____ breaks hydrogen bonds between the two template strands and moves the replication fork forward.

helicase

During homologous recombination, a single-stranded DNA molecule of one chromosome pairs with a single-stranded DNA molecule of another homologous chromosome, forming _____ DNA.

heteroduplex

How many bands does the scientist expect to see in the second round of density-gradient centrifugation if all original histone proteins remain on one strand of DNA and new histones attach to the other strands during replication?

One lower band containing the original histone octamers and one higher band containing the new histone octamers

How does a eukaryotic cell ensure that DNA is replicated only once at each origin per cell cycle?

During the G1 phase, the cell uses an origin-recognition complex and licensing factors to identify origins of replication and recruit and initiator complex that forms a helicase. After replication begins in S phase, the initiator complex is prevented from binding to DNA