test 4 - Exam Name___________________________________...

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Unformatted text preview: Exam Name___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Mutations which arise in nature, from no particular external agent are called 1) A) natural mutations. B) cosmic mutations. C) induced mutations. D) spontaneous mutations. E) chromosomal aberrations. Answer: D Explanation: A) B) C) D) E) 2) Nutritional mutations can be defined as 2) A) all strains that are not auxotrophic. B) those mutations that change the composition of the medium. C) those mutations that do not allow an organism to grow on minimal medium, but do allow the organism to grow on complete medium. D) those belonging to the group called prototrophs. E) those mutations caused by site- specific mutagenesis. Answer: C Explanation: A) B) C) D) E) 3) Assume that you are examining a series of human pedigrees and observe the following: there are more males abnormal than females; there are approximately half the grandsons of abnormal males, abnormal; and some females are abnormal, but usually only if their maternal grandfather was abnormal and their mother married an abnormal male. What type of inheritance might be occurring? 3) A) multiple factor B) Y- linked dominant C) sex- linked recessive D) autosomal dominant, sex- limited E) sex- linked dominant Answer: C Explanation: A) B) C) D) E) 1 4) Two formal terms used to describe categories of mutational nucleotide substitutions in DNA are called 4) A) error prone and spontaneous. B) sense and antisense. C) euchromatic and heterochromatic. D) transversions and transitions. E) base analogues and frameshift. Answer: D Explanation: A) B) C) D) E) 5) Name two mutagens that would be classified as base analogues. 5) A) 5- bromouracil and 2- aminopurine B) acridine orange and proflavin C) hydroxyurea and peroxidase D) ethylmethane sulfonate and ethylmethylketone peroxide E) ultraviolet light and cosmic radiation Answer: A Explanation: A) B) C) D) E) 6) A class of mutations that results in multiple contiguous amino acid changes in proteins is likely to be the following: 6) A) transversion. B) frameshift. C) base analogue. D) recombinant. E) transition. Answer: B Explanation: A) B) C) D) E) 2 7) Ultraviolet light causes pyrimidine dimers to form in DNA. Some individuals are genetically incapable of repairing some dimers at "normal" rates. Such individuals are likely to suffer from 7) A) xeroderma pigmentosum. B) Huntington disease. C) phenylketonuria. D) muscular dystrophy. E) SCID. Answer: A Explanation: A) B) C) D) E) SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 8) Assume that you are working with a mutant, nutritionally deficient strain of Escherichia coli and that you isolate "revertants," which are nutritional- normal. Describe, at the molecular level, possible causes for the "reversion to wild type." 8) Answer: There are two general classes of events that could be involved: true reversion or suppression. True reversion would involve a precise correction of the originalsuppression....
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