46 Cards in this Set
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A restriction enzyme is a type of endonuclease that recognizes and cleaves double-stranded DNA at a specific sequence.
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TRUE
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The polymerase chain reaction is a way of using DNA replication to amplify one sequence in a complex sequence mixture to any desired degree of relative concentration
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TRUE
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A null mutation at haplo-sufficient locus would be expected to be dominant to the wild-type allele.
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FALSE
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A null mutation at a haplo-insufficient locus would be expected to be dominant to the wild-type allele.
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TRUE
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In diploid organisms, most loci are haplo-insufficient
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FALSE
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A protein-null mutation (a mutation in which no protein is expressed at all) is always recessive to the wild-type allele.
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FALSE
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A dominant-negative mutation cannot be a protein-null mutation
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TRUE
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Dominant negative mutations usually occur in genes that encode polypeptides that function in dimers or high-order protein complexes.
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TRUE
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In incomplete (partial) dominance, the phenotype of the heterozygote is intermediate between the phenotypes of the two homozygotes
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TRUE
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In a cross involving incomplete dominance, the number of different genotypic classes is always greater than the number of different phenotypic classes.
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FALSE
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In general, if a mutant allele is dominant to the wild-type allele, the mutant homozygote usually exhibits the same phenotype as the heterozygote
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FALSE
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In codominance, the heterozygote exhibits the phenotypes controlled by both alleles.
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TRUE
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The interaction between the Rh+ and Rh- alleles is an example of codominance.
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FALSE
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The MN blood group phenotype is an example of incomplete dominance.
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FALSE
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The interaction between the I^ allele and i allele in the ABO blood group is an example of codominance.
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FALSE
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It is not possible for a mutant allele to be both dominant and recessive with respect to the wild-type allele.
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FALSE
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It is not possible for a mutant allele to be both recessive and codominant with respect to the wild-type allele.
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FALSE
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If a monohybrid cross yields a 2:1 phenotype ratio, the most likely explanation is that one of the alleles is recessive lethal.
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TRUE
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An epistatic allele is one that overrides the alleles of a second gene so that it doesn't matter what the genotype at the second gene is.
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TRUE
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Phenylketonuria is a disease caused by a mutation in the gene that encodes the enzyme responsible for converting phenylalanine to tyrosine.
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TRUE
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In a doubly mutant individual, the alkaptonuria mutation would be expected to be epistatic to the phenylketonuria mutation.
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FALSE
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If ten individuals are heterozygous for a dominant mutant allele and the wild-type allele (M/m) but only eight of those individuals express the mutant phenotype, the gene would be said to exhibit incomplete dominance.
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FALSE
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If three individuals with the same red coat-color genotype exhibit coat-colors that are different shades of red, the gene would be said to exhibit variable expressivity.
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TRUE
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If two mutations that cause the same phenotype when homozygous also cause the same phenotype when heterozygous with each other, those two alleles are said to complement each other.
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FALSE
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In general two alleles that complement each other contain mutations in the same gene.
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FALSE
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A plasmid is a small circular chromosome that is present in some but not all cells of a bacterial species.
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TRUE
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The ability to form a conjugative pilus is dependent on the presence of some types of plamsids including F plasmids and R plasmids.
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TRUE
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A bacterial cell that contains a free F plasmid (not integrated into the main genome) is called an F+ cell.
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TRUE
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A prototrophic bacterium is one that requires no complex organic molecules in its growth medium other than an energy source.
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TRUE
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A strain of E. coli that requires methionine and biotin as supplements to the minimal medium in order to grow is called auxotrophic.
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TRUE
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An Hfr strain is one in which an F plasmid has integrated into the bacterial chromosome.
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TRUE
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Integration of an F plasmid into the bacterial chromosome requires a double crossover (or an even number of crossovers).
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FALSE
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Integration of a segment of the donor chromosome into the recipient chromosome following conjugation requires a double crossover (or an even number of crossovers).
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TRUE
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In the Lederburg-Tatum experiment, co-incubation of two multiply mutant (auxotrophic) strains in the same tube enabled development of prototrophic cells but if the same strains were incubated separately, no prototrophs developed.
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TRUE
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In the Lederburg-Tatum experiment, prototrophic cells also developed when the multiply auxotrophic strains were incubated in opposite arms of a U-tube separated only by a filter that allowed complex organic molecules to pass back and forth.
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FALSE
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The E. coli chromosome is measured in minutes, the minutes referring to the time a gene is transferred from an Hfr cell to an F-cell in an interrupted-mating conjugation experiment.
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TRUE
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In Hfr x F- mating, the F plasmid is the first part of the chromosome to be transferred so that nearly all of the recipiennts become Hfr cells.
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FALSE
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In bacterial recombination, only one of the recombination products persists.
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TRUE
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R plasmids cannot form pili or transfer themselves to other cells.
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FALSE
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In transformation, the transforming DNA is actively imported by the recipient cell.
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TRUE
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The principle of mapping in transformation experiments is that the probability of co-transformation of two genes is inversely proportional to the distance between them.
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TRUE
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A plaque is a clear area on a plate where no bacteriophage are present.
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FALSE
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Like bacterial recombination, phage recombination is non-reciprocal because only one of the crossover products persists.
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FALSE
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In transduction, a phage incorporates a segment of bacterial chromosome into its head and transfers it to another bacterial cell.
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TRUE
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The probability of cotransduction is dependent not only on the distance between the two bacterial genes but also on the size of the phage head.
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TRUE
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There is only one site in the E. coli chromosome at which the F plasmid can insert.
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FALSE
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BIOL 240: Exam 1