Genetics Test 4 Ch. 15 Flashcards
1) Half of the palindromic restriction site that the endonuclease PstI recognizes, binds, and cleaves is 5’- CTG________- 3’. What is the complete sequence?<br></br>A) 5’- CTGCAG- 3’ B) 5’- CTGGTC- 3’<br></br>C) 5’- CTGCTG- 3’<br></br>D) 5’- CTGGAG- 3’<br></br> E) 5’- CTGGAC- 3’
Answer: A
2) The human genome is 3 × 109 bp in length. Calculate how many fragments would result from thecomplete digestion of the human genome with EcoRI (5’- GAATTC- 3’).<br></br>A) 1.17 × 107 B) 4.32 × 105 C) 7.32 × 105 D) 9.72 × 105 E) 4.58 × 104
Answer: C
3) Assume that a plasmid is 4000 base pairs in length and has restriction sites at the following locations: 600, 1000, 2200, and 3800. Give the expected sizes of the restriction fragments following complete digestion.<br></br>A) 200 bp, 400 bp, 600 bp, 1200 bp, 1800 bp<br></br>B) 400 bp, 800 bp, 1000 bp, 1800 bp<br></br>C) 400 bp, 800 bp, 1200 bp, 1600 bp<br></br>D) 200 bp, 600 bp, 1200 bp, 1600 bp<br></br>E) 200 bp, 800 bp, 1200 bp, 1800 bp
Answer: C
5) You have a linear DNA fragment of 1600 bp. To characterize it, you decide to make a restrictionmap. Cutting with one enzyme, you show by electrophoresis that the fragments produced are 400 and 1200 bp. Cutting the same DNA with another enzyme you recover 700 and 900 bp fragments. After treatment with both enzymes, fragments were 300, 400, and 900 bp. Which of the following order of fragments, if any, best represents the restriction map?<br></br>A) 400/ 300/ 900<br></br>B) 900/ 400/ 300<br></br>C) 400/ 900/ 300<br></br>D) 300/ 400/ 900<br></br>E) It is not possible to determine the order.
Answer: A
6) In producing a recombinant plasmid to be used to clone a given donor insert, it is possible to cutboth the donor and plasmid with the same restriction enzyme, resulting in complementary sticky ends. Assuming plenty of plasmid DNA is available, why is further selection necessary before the introduction of the plasmid into a cellular system? <br></br>A) Some donor pieces will remain uninserted.<br></br>B) Contamination will have introduced other donor inserts.<br></br>C) Some donor inserts will be sensitive to particular antibiotics.<br></br>D) Some donor strands will be inserted with an incorrect orientation.<br></br>E) Some donor inserts will be single stranded and deteriorate.
Answer: D
7) In selecting recombinant bacteria, cells are chosen that are resistant to a specific antibiotic. How are the bacteria made resistant?<br></br>A) Resistance is activated when the cells are provided with the antibiotic<br></br>B) Resistance is activated by the recombination event.<br></br>C) The antibiotic resistance gene is encoded in the vector. D) They are pre- selected for the experiment on this basis.<br></br>E) The antibiotic resistance gene is encoded on the donor insert.
Answer: C
8) If bacteria transformed with a recombinant pUC18 plasmid produce white colonies when grown on plates containing ampicillin and Xgal, which of the following is least likely? <br></br>A) They produce functional Ά- galactosidase that cleaves X- gal.<br></br>B) They carry a vector with the bla gene used as the selectable marker.<br></br>C) They carry a vector with a lacZ gene that has been disrupted and rendered nonfunctional.<br></br>D) They carry a vector that contains a DNA fragment inserted into the multiple cloning site.<br></br>E) They produce Ά- lactamase that provides resistance to ampicillin.
Answer: A
9) Which of the following lists the steps for cDNA library preparation in the correct order?<br></br>I. Partially degrade the mRNA with RNase H<br></br>II. Isolate mRNA from a specific cell/ tissue with an oligo- dT primer that hybridizes to poly- A tail<br></br>III. Synthesize a strand of cDNA using DNA polymerase with mRNA fragments as primers<br></br>IV. Ligate cDNAs into a cloning vector<br></br>V. Create a single- stranded DNA molecule complementary to the mRNA using reverse transcriptase<br></br>A) II, V, IV, III, I<br></br>B) II, V, I, III, IV<br></br>C) I, II, III, IV, V<br></br>D) II, III, V, I, IV<br></br>E) V, III, I, IV, II
Answer: B
10) Which of the following is true of the sequences found in DNA libraries from human tissues? <br></br> A) Those in a muscle cDNA library should all be present in a brain genomic library.<br></br>B) Those in a brain cDNA library should not be found within a muscle genomic library.<br></br>C) Those in a brain cDNA library should all be present a muscle cDNA library.<br></br>D) Those in a muscle genomic library should not be found within a brain genomic library.<br></br>E) Those in a muscle cDNA library should all be present in a brain cDNA library.
Answer: A
11) Efficient production of eukaryotic proteins in E. coli may require all of the following except? <br></br>A) altered codon usage within the heterologous sequences to approximate the codon bias in E. coli<br></br>B) the use of cDNAs, that are free of introns, as eukaryotic transgenes<br></br>C) an E. coli expression vector with a promoter sequence that binds RNA polymerase<br></br>D) an E. coli expression vector with a Shine- Dalgarno sequence for efficient translation<br></br>E) a negative selectable marker to select against nonhomologous recombination events
Answer: E
12) Which of the following best lists the correct order of the steps taken to produce human insulin in E.coli in the 1970s?<br></br>I. Each insulin chain was cloned into an expression vector as a continuation of the lacZ reading fra resulting in a fusion protein for each chain.<br></br>II. Disulfide bonds were induced to form between the cysteine residues of the purified insulin A an chains.<br></br>III. Both human insulin genes were reverse translated to create synthetic genes.<br></br>IV. EcoRI and BamHI restriction sites were added to the ends of the DNA to facilitate directional cloning of each into a separate plasmid vector.<br></br>A) III, I, II, IV <br></br>B) I, II, III, IV <br></br>C) I, III, IV, II <br></br>D) III, IV, I, II<br></br>E) IV, III, I, II
Answer: D
13) Which of the following is a possible advantage for the environment of having farmers use plants that genetically produce Bt toxin?<br></br>A) Harvesting plants with these genes is less disturbing to the soil layers where they are planted.<br></br>B) Plants with genes for the toxin are eaten less often by insects, and therefore less insecticide is needed.<br></br>C) Plants with these genes must be sprayed with the organism, but need much less than other plants.<br></br>D) Plants that produce Bt toxin must be grown from new seeds each season, and therefore fewer of them are planted.<br></br>E) Bt toxin is advantageous to many species of invertebrates that grow in the same fields.
Answer: B
14) In using Agrobacterium tumefaciens to transfer genes into plants, what is transferred from bacterium to plant?<br></br>A) Ti plasmid<br></br>B) opines<br></br>C) the entire bacterium<br></br>D) T- DNA<br></br>E) only the recombining sequence
Answer: D
15) Which of the following is FALSE regarding P element- mediated transformation? <br></br>A) The gene of interest is typically inserted in the vector plasmid between the P element inverted repeat end sequences.<br></br>B) The selectable marker is typically inserted in the vector plasmid between the P element inverted repeat end sequences.<br></br>C) The transposase activity inserts P elements into the genome at specific positions in the genome.<br></br>D) P elements transpose only in the germ- line cells of Drosophila.<br></br>E) A second plasmid can be used to supply the transposase activity in trans.
Answer: C
16) Suppose you have engineered a plasmid vector in order to produce a functional animal protein in E. coli. But the product you collect, while it has the correct amino acid sequence, is in fact nonfunctional. What might you try that would have a greater chance of success?<br></br>A) using a host other than E. coli that does not have the same codon bias<br></br>B) using yeast artificial chromosomes that can hold longer sequences<br></br>C) a eukaryotic expression vector that includes sequences for controlling posttranslational effects<br></br>D) a eukaryotic expression vector that has sequences for regulating transcription <br></br>E) treatment of the posttranslation proteins to add signal sequences
Answer: E
17) Why might the expression of a transgene be especially abnormal in vertebrates with larger average size of genes and amount of heterochromatin in their genomes?<br></br>A) homologous recombination<br></br>B) vector insufficiency<br></br>C) unequal crossing over<br></br>D) mitotic recombination<br></br>E) position effect
Answer: E
18) Which of the following is FALSE regarding the formation of transgenic animals?<br></br>A) If some cells of the embryo do not receive the introduced DNA, the result is an organism with cells of different genotypes; the organism is known as a chimera.<br></br>B) DNA is usually inserted into eggs or embryos since totipotency is not characteristic of most animal cells.<br></br>C) Homologous recombination occurs much more frequency than illegitimate recombination.<br></br>D) Either integration of multiple copies of the transgene or position effect can lead to variability in the expression of the transgene.<br></br>E) For a transgenic animal line to be produced from a chimera, the transgene must be carried by germ line or germ cells.
Answer: C
