MasteringBiology: Chapter 12 – Flashcards
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Restriction enzymes
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cut DNA at specific sites
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"Sticky ends" are
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DNA fragments with single-stranded ends.
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The fragments produced by most restriction enzymes have _____.
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complementary single-stranded ends
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An enzyme that "cuts" DNA at a specific sequence of nucleotide bases is called _____.
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Restriction enzymes
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To create a molecule of recombinant DNA, which of the following is cut with a restriction enzyme?
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Target DNA, Starting DNA
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Check each of the true statements about the proteins involved in cutting and pasting DNA. More than one statement may be true.
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A restriction enzyme cuts DNA while DNA ligase pastes DNA.
A particular restriction enzyme only cuts DNA at one very specific DNA sequence.
DNA ligase pastes together segments of DNA with matching sticky ends.
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Which one of the following statements is correct?
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If a restriction enzyme is combined with a piece of DNA that contains its restriction site, the result will be restriction fragments.
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Which of the following is the best definition of a genomic library?
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a collection of cloned DNA fragments that includes an organism's entire genome
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The enzyme that converts information stored in RNA to information stored in DNA is
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reverse transcriptase.
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DNA synthesized using an RNA template is called _____.
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cDNA
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The type of recombinant bacteria most often used to mass-produce genes is
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Escherichia coli.
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Insulin used for the treatment of diabetes in humans is now obtained from _____.
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bacteria
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Cloning human genes into the plasmids of bacteria has enabled scientists to __________.
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use bacteria as "factories" for protein products
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Human growth hormone is a secreted protein that stimulates growth and cell reproduction. In the 1960s it was discovered that this was an effective treatment for a form of dwarfism. However, before it was genetically engineered, it was _____.
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harvested from cadavers
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The advantage of being able to clone the gene for human insulin is that
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human insulin is less likely to cause harmful side effects than cow, pig, or horse insulin.
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Which of the following statements about DNA technology is false?
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DNA technology is now used to create cells that can identify and kill cancer cells.
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Plants are being engineered to produce pesticides; therefore, _____.
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farmers can reduce chemical use
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Researchers are trying to make a genetically modified (GM) pig that expresses bovine (cow) growth hormone to make it grow bigger. They isolated the bovine growth hormone gene, cut it and a plasmid with the same restriction enzyme, and mixed them together. They inserted the mixture into pig zygotes, but only normal pigs, not GM pigs, grew. What did they likely do wrong?
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They forgot to add DNA ligase after mixing the plasmid and gene together.
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Transgenic organisms are only scientifically or commercially useful if _____.
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the inserted ("foreign") gene is expressed in the host organism
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Concerns have been raised as to the safety of genetically modified organisms (GMOs). Which of the following would be a concern when modifying a plant to be resistant to a broad-spectrum herbicide?
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the production of herbicide-resistant weeds
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Which of the following has not been a significant issue in the creation of genetically modified (GM) organisms?
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the fact that GM organisms cannot be modified to prevent them from reproducing once they pass beyond the experimental stage
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In order for gene therapy to be permanent in the patient being treated,
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the normal gene must be transferred to somatic cells that can continuously multiply.
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What does the process of gene therapy involve?
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It adds a functioning version of the defective gene to the cells of an individual.
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DNA profiling is a forensic procedure being utilized to identify individuals. This technique _____.
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compares the DNA banding patterns of small segments of the genome
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In a PCR reaction, the strands of DNA are first separated by ___.
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heating
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When is PCR particularly applicable?
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When there are small quantities of DNA to analyze
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What is the correct sequence of events that occur in a PCR reaction?
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separation of DNA strands; addition of primers; use of DNA polymerase to produce second strand of DNA
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DNA polymerase is a heat-sensitive enzyme. What is one thing that would need to be considered concerning the activity of this enzyme in PCR when the temperature is heated during each cycle to separate the DNA strands?
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that the DNA polymerase could be denatured
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What is the function of the polymerase chain reaction (PCR)?
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It can make a large amount of DNA from a tiny amount.
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Gel electrophoresis separates DNA molecules on the basis of size. Which of the following DNA molecules would move the slowest?
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F plasmid (100 kb)
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Gel electrophoresis sorts DNA molecules on the basis of their
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size.
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What is the purpose of gel electrophoresis?
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It allows for the separation of fragments of DNA.
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Which of the following pieces of evidence would be considered the best for establishing biological relatedness?
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a very close match in the DNA profile
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Which of the following statements regarding DNA is false?
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Human and E. coli genomes contain approximately the same proportions of noncoding DNA.
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Approximately what percentage of the human genome actually encodes proteins?
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3%
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Approximately what percentage of the human genome is identical to that of a chimpanzee?
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98.8%
