MA 7 – Flashcards
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Which of the following molecules is not required for a PCR reaction?
Ligase
DNTPs
DNA
Primer
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ligase-Ligase is not required for a PCR reaction. The enzyme used during PCR is a thermostable DNA polymerase.
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The thermostability of Taq polymerase is required during the annealing phase of PCR.
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false-The annealing phase takes place at the lowest temperature of PCR. Taq polymerase is derived from bacteria that live in hot springs, so the enzyme is thermostable, meaning that its enzymatic properties can withstand the high temperatures needed for denaturation.
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What is the purpose of raising the temperature to 90-95°C at the beginning of each cycle of PCR?
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To separate the double‑stranded DNA-The temperature is raised to denature the double‑stranded DNA molecule into single strands.
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The data obtained from the Meselson-Stahl experiment after one generation of replication eliminated the dispersive model of DNA replication.
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F-The data obtained from the Meselson-Stahl experiment after one generation was consistent with both the semiconservative and the dispersive model of DNA replication. The conservative model of DNA replication was eliminated because it predicted that there would be two bands representing the original DNA at one density and the newly replicated DNA at a different density.
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Which enzyme catalyzes the addition of nucleotides to a growing DNA chain?
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DNA polymerase-DNA polymerase catalyzes the addition of nucleotides to a growing DNA chain.
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Which of the following statements about DNA replication is true?
Okazaki fragments are DNA fragments synthesized on the leading strand.
DNA gyrase unwinds the DNA double helix.
Single‑strand binding proteins stabilize the open conformation of the unwound DNA.
DNA polymerase adds dNTP monomers in the 3′-5′ direction.
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Single‑strand binding proteins stabilize the open conformation of the unwound DNA.-Once helicase unwinds the double helix, single‑strand binding proteins bind to the open DNA and prevent it from winding together again.
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he role of the primers in PCR is _______.
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to define the target region and provide a 3' end that can be extended by taq polymerase-Primers bind to end of the target DNA strands, then taq polymerase synthesizes a new strand using the target DNA as a template.
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If there are five molecules of DNA containing the target region at the beginning of a PCR reaction, how many copies of the target will be present after three rounds of amplification?
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40-doubled after each replication cycle
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Immediately after the primers have annealed to the target sequence
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the temperature is raised so that taq polymerase can extend the primers-The temperature is raised to 70-75∘C, the temperature over which taq polymerase is optimally active.
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Which three steps constitute a PCR cycle?
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denaturation, annealing, and extension-The double-stranded product is denatured, the primers anneal to the target sequence, and then DNA synthesis (extension) by Taq polymerase proceeds.
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The discontinuous aspect of replication of DNA in vivo is caused by
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the 5' to 3' polarity restriction
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During DNA replication, an open section of DNA, in which a DNA polymerase can replicate DNA, is called a
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replication fork
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After replication is complete, the new DNAs, called _____, are identical to each other.
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daughter DNA
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The new DNA strand that grows continuously in the 5' to 3' direction is called the
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leading strand
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are the short sections of DNA that are synthesized on the lagging strand of the replicating DNA.
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okazaki fragments
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The enzyme that can replicate DNA is called
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DNA polymerase
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Which of the following statements about DNA replication is true?
DNA synthesis is conservative on the leading strand and semiconservative on the lagging strand.
The two replication forks move in the same direction.
DNA synthesis is continuous on the leading strand and discontinuous on the lagging strand.
DNA synthesis is discontinuous on the leading strand.
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DNA synthesis is continuous on the leading strand and discontinuous on the lagging strand.
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Okazaki fragments are short DNA fragments synthesized in a _____manner.
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discontinuous
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RNA primers are formed by ____ and serve as an initiation point for DNA synthesis on the template.
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RNA primase
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Okazaki fragments appear on the ___strand during DNA replication.
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lagging
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Okazaki fragments appear on the lagging strand during DNA replication.
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DNA polymerase I
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DNA ligase then forms ___bonds between DNA Okazaki fragments.
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phosphodiester
