Biology Final - Biotechnology
During which step in the PCR cycle do primers form bonds with a single-stranded template?
Annealing. (Primers form hydrogen bonds with the single-stranded DNA template during the annealing step.)
In recombinant DNA methods, the term vector can refer to
a plasmid used to transfer DNA into a living cell.
Which enzyme was used to produce the molecule in the figure?
a restriction enzyme
Which of the following procedures would produce RFLPs?
incubating DNA with restriction enzymes
In gel electrophoresis DNA molecules migrate from _____ to _____ ends of the gel.
negative ... positive
Which of the following would not be true of cDNA produced using human brain tissue as the starting material?
not true: It could be used to create a complete genomic library. true: It could be used as a probe to detect genes expressed in the brain. It lacks the introns of the human genes. It could be amplified by the polymerase chain reaction. It is produced from mRNA using reverse transcriptase.
A paleontologist has recovered a bit of tissue from the 400-year-old preserved skin of an extinct dodo (a bird). The researcher would like to compare a specific region of the DNA from the sample with DNA from living birds. Which of the following would be most useful for increasing the amount of dodo DNA available for testing?
polymerase chain reaction (PCR)
Expression of a cloned eukaryotic gene in a bacterial cell involves many challenges. The use of mRNA and reverse transcriptase is part of a strategy to solve the problem of
post-transcriptional processing
DNA fragments from a gel are transferred to a nitrocellulose paper during the procedure called Southern blotting. What is the purpose of transferring the DNA from a gel to a nitrocellulose paper?
to attach the DNA fragments to a permanent substrate
What is the enzymatic function of restriction enzymes?
to cleave nucleic acids at specific sites
Gene therapy
had apparent success in treating disorders involving bone marrow cells.
What defect causes pituitary dwarfism?
Lack of growth hormone
In order to insert a human gene into a plasmid, both must _____
be cut by the same restriction enzyme
DNA fragment B consists of _____ base pairs.
1,405
True or false? Comparison of the sequences of the same gene across species can give some insight into the existence of a common ancestor with that gene.
true (DNA sequence comparisons are a powerful tool by which to estimate how closely related different species are along the evolutionary timeline)
Which of the following best describes the complete sequence of steps occurring during every cycle of PCR? 1. The primers hybridize to the target DNA. 2. The mixture is heated to a high temperature to denature the double stranded target DNA. 3. Fresh DNA polymerase is added. 4. DNA polymerase extends the primers to make a copy of the target DNA.
2, 1, 4
How many DNA molecules would there be after four rounds of PCR if the initial reaction mixture contained two molecules?
32 (Thirty-two DNA molecules are produced if two molecules are doubled four times.)
In this example the marker DNA includes fragments that have 23,130, 9,416, 6,557, 4,361, 2,322, 2,027, and 564 base pairs. Approximately how many base pairs are in the DNA fragment indicated by the letter A?
6,557
How does a genomic library differ from a cDNA library?
A genomic library can be made using a restriction enzyme and DNA ligase only, whereas a cDNA library requires both of these as well as reverse transcriptase and DNA polymerase.
What is the polymerase chain reaction (PCR)?
A method to amplify a fragment of DNA. (PCR is an in vitro DNA synthesis reaction that produces many copies of a single DNA fragment.)
What is genetic cloning?
A method to produce many copies of a gene
Which of the following tools of recombinant DNA technology is incorrectly paired with its use?
Correctly paired: restriction enzyme - production of RFLPs reverse transcriptase - production of cDNA from mRNA DNA polymerase - used in a polymerase chain reaction to amplify sections of DNA electrophoresis - separation of DNA fragments Incorrectly paired: DNA ligase - enzyme that cuts DNA, creating the sticky ends of restriction fragments
What enzyme forms covalent bonds between restriction fragments?
DNA ligase
Which of the following seals the sticky ends of restriction fragments to make recombinant DNA?
DNA ligase
During which step in the PCR cycle are nucleotides used?
Extension. (Nucleotides are used to synthesize the complementary strand to the DNA template during the extension step.)
What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium? I. Transform bacteria with recombinant DNA molecule. II. Cut the plasmid DNA using restriction enzymes. III. Extract plasmid DNA from bacterial cells. IV. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. V. Use ligase to seal plasmid DNA to nonplasmid DNA.
III, II, IV, V, I
Which of the following statements best describes the function of reverse transcriptase?
It makes complementary DNA (cDNA) from mRNA. (The function of reverse transcriptase is similar to the reverse of transcription; it makes a single strand of complementary DNA (cDNA) from mRNA.)
Which of the following steps would be performed last when screening a cDNA library?
Match the region of radioactivity on the filter with the corresponding plate. (This step allows researchers to match the colony on the filter with the colony of the bacterial plate so the correct colony can be grown for further study. It would be the last step in screening a cDNA library.)
How can large quantities of protein be produced from a bacterial colony containing the gene of interest?
Put a cDNA encoding the protein into a plasmid with a bacterial promoter sequence. (Once a cDNA is put into a plasmid with a bacterial promoter, the bacteria will transcribe and translate the gene.)
Which was developed by a British researcher and causes DNA sequences to be transferred to a membrane and identified with a probe?
Southern blotting
What information can not be obtained from the sequence of a gene?
Whether the gene is methylated. (Although the gene's sequence may reveal the presence of methylation targets like cytosine (C), it does not give information about whether such bases have been methylated.)
Sequencing an entire genome, such as that of C. elegans, a nematode, is most important because
a sequence that is found to have a particular function in the nematode is likely to have a closely related function in vertebrates.
A eukaryotic gene has "sticky ends" produced by the restriction endonuclease EcoRI. The gene is added to a mixture containing EcoRI and a bacterial plasmid that carries two genes conferring resistance to ampicillin and tetracycline. The plasmid has one recognition site for EcoRI located in the tetracycline resistance gene. This mixture is incubated for several hours, exposed to DNA ligase, and then added to bacteria growing in nutrient broth. The bacteria are allowed to grow overnight and are streaked on a plate using a technique that produces isolated colonies that are clones of the original. Samples of these colonies are then grown in four different media: nutrient broth plus ampicillin, nutrient broth plus tetracycline, nutrient broth plus ampicillin and tetracycline, and nutrient broth without antibiotics. A principal problem with inserting an unmodified mammalian gene into a bacterial plasmid, and then getting that gene expressed in bacteria, is that
bacteria cannot remove eukaryotic introns.
In this example the marker DNA includes fragments that have 23,130, 9,416, 6,557, 4,361, 2,322, 2,027, and 564 base pairs. Approximately how many base pairs are in the DNA fragment indicated by the letter B?
between 6,557 and 4,361 base pairs
Assume that you are trying to insert a gene into a plasmid. Someone gives you a preparation of genomic DNA that has been cut with restriction enzyme X. The gene you wish to insert has sites on both ends for cutting by restriction enzyme Y. You have a plasmid with a single site for Y, but not for X. Your strategy should be to
cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme.
True or false? The use of growth hormone isolated from cadavers was banned mainly because there were not enough cadavers to supply the hormone.
false
True or false? The Taq enzyme is a type of DNA polymerase that allows researchers to separate the DNA strands during the annealing step of the PCR cycle without destroying the polymerase.
false (Taq polymerase is derived from a species of bacteria living in hot springs, which makes it stable at the high temperature required for the denaturation step of PCR.)
In 1997, Dolly the sheep was cloned. Which of the following processes was used?
fusion of an adult cell's nucleus with an enucleated sheep egg, followed by incubation in a surrogate
Restriction fragments of DNA are typically separated from one another by which process?
gel electrophoresis
Which of the following separates molecules by movement due to size and electrical charge?
gel electrophoresis
Which of the following produces multiple identical copies of a gene for basic research or for large-scale production of a gene product?
gene cloning
The DNA fragments making up a genomic library are generally contained in
recombinant plasmids of bacteria.
RFLP analysis can be used to distinguish between alleles based on differences in which of the following?
restriction enzyme recognition sites between the alleles
Which of the following cuts DNA molecules at specific locations?
restriction enzymes
Which of the following is used to make complementary DNA (cDNA) from RNA?
reverse transcriptase
A gene that contains introns can be made shorter (but remain functional) for genetic engineering purposes by using
reverse transcriptase to reconstruct the gene from its mRNA
The segment of DNA shown in Figure 20.2 has restriction sites I and II, which create restriction fragments A, B, and C. Which of the gels produced by electrophoresis shown below best represents the separation and identity of these fragments?
see picture
Dideoxyribonucleotide chain-termination is a method of
sequencing DNA.
The unpaired nucleotides produced by the action of restriction enzymes are referred to as _____.
sticky ends
True or false? The term "sticky ends" refers to the overhanging ends on DNA that are generated by restriction enzymes, which can base pair with any DNA molecules that contain complementary sticky ends.
true
