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132 Cards in this Set
- Front
- Back
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During which of the following stages of the cell cycle would a chromosome consist of only a single chromatid?
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G1
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Genes on the X chromosome of mammals and Drosophila are particularly suitable for genetic study because....
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males have only one X and most genes behave as haploids
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Males with one copy of an X-linked gene are said to be ___ for that gene.
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hemizygous
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In Drosophila virilis, nuclei of somatic cells contain 12 chromosomes while nuclei of sperm cells contain only 6 chromosomes. what does "n" equal for this species?
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6
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In a monohybrid cross between a homozygous dominant parent a homozygous recessive parent, what proportion of homozygotes is expected among the F2 offspring?
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1/2
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Ascospores are diploid cells that can germinate, replicate by mitosis, and survive as diploid individuals.
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false
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In tetrad analysis, the criterion for linkage of two genes is
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PD > NPD
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In tetrad analysis, NPD asci result from
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independent assortment of unlinked genes or double crossovers between linked genes
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If you are doing a tetrad analysis of linked genes, NPD occurs only in the following situation:
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a double crossover involving 4 strands
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In a monohybrid cross between parents Aa x Aa, (both P) what proportion of heterzygotes is expected among the F1 offspring?
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1/2
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The second generation of offspring from the parents are called....
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F2
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A rare autosomal dominant trait in a pedigree is indicated by which pattern of inheritance?
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vertical
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recombination frequencies near 50% suggest that
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two genes are on different chromosomes, or two genes are on the same chromosome but lie very far apart
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A person who has type A blood has ...
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anti-B bodies
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What aspect of chromosomes behavior most clearly accounts for Mendel's law of segregation?
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Movement of homologous chromosomes to opposite poles at anaphase 1 of meisosis
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m examining the reseults from a three-point cross between two drosophila. Wince the genes I'm examining are on the X chromosome, I can look just at the males. The parental classes are w+y+m/Y. the double crossover classes are w+ym+/Y and wy+m/Y. Which gene is in the middle?
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w
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which of the following lines produce offspring that carry specific parental traits that remain constant from generation to generation?
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pure-breeding
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Which of the following was probably the first genetic material on Earth?
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RNA
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A ___ is done to determine the genotype of an individual with a dominant phenotype
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testcross
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An alternative form of a single gene is known as
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allele
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When the same gene is related to mental retardation and skin pigmentation, as in the disease phenylketonuria, it can be described as__
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pleiotropy
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What does a black square in a pedigree chart symbolize?
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male with the disease
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Mutations are the source of new alleles....
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True
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recombination involves the breakage and reunion of DNA molecules from...
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homologous nonsister chromatids
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When a late blooming pea and an early blooming pea are crossed and an intermediate phenotype occurs, this result would suggest incomplete dominance inheritance.
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True
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Red-green color blindness is controlled by an X chromosomal gene in humans. A normal man and normal woman whose fathers are both color blind marry. What is the probability that their first child will be color blind?
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1/4
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cross-fertilization and reciprocal crosses are different
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True
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During gamete formation, different pairs of alleles on different chromosomes assort independently of each other.
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True
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If the map distance between genes A and B is 10 map units and the map distance between genes B and C is 25 map units, what is the map distance between genes A and C?
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either 15 map units or 35 map units, depending on the order of the genes.
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___ occurs when chromosomes fail to separate properly during meiosis.
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nodisjunction
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Sickle cell anemia is a recessive trait in humans. In a cross between a father and mother who are both heterozygous for the gene, what is the probability that their first three children will have sickle cell anemia?
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1/64
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crossing over between homologous chromosomes occurs at which of the following stages of meiosis?
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prophase 1
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the nonsex chromosomes are called autosomes.
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True
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Duplications of the genes, followed by mutation, is responsible for the formation of ___
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gene families.
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In codominance, F1 hybrids show the traits of both parents.
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True
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If an individual is a heterozygote for one trait, s/he must be heterozygous for all traits.
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False
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In complementary gene action, recessive alleles of two or more genes are required to generate a particular trait.
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False
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Which aspect(s) of chromosome behavior is/are primarily responsible for the tremendous amount of genetic variability associated with sexual reproduction?
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Both crossing over between homologous chromosomes during prophase 1 of meiosis and independent alignment of different homologous pairs on the metaphase 1 spindle contribute to genetic variability.
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If the parents of a family already have two boys, what is the probability that the next two offspring will be girls?
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1/4
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The Bombay phenotype is an example of
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recessive epistasis
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Mitosis results in ___ chromosome number, whereas meiosis results in ___ chromosome number.
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no change in, a reduction by half in
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Which of the following processes can generate recombinant gametes?
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crossing over between two linked heterozygous loci and independent assortment of two unlinked heterozygous loci.
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sickle cell anemia is a recessive trait in humans. In a cross between a father and mother who are both heterozygous for the gene, what is the probability that a child will have sickle cell anemia?
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1/4
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Each nucleotide of DNA contains
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a deoxyribose sugar, a phosphate, and a nitrogenous base
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chromosome banding patterns can be used for which of the following?
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to analyze chromosomal differences between species, to locate genes, and to reveal the cause of certain genetic diseases.
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which of the following is NOT true about DNA polymerase.
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It can replace RNA primer with DNA at the 5' end.
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If 25% of the bases in a region of the mouse genome are cytosine, what percentage in that region are adenine?
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25%
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The results of the Luria Delbruck fluctuation experiment indicated that....
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bacteria become resistant to phage by random spontaneous mutation
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only multimeric proteins that have quaternary structure.
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true
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The first level of compaction of DNA consists of
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DNA winding around histones to form small nucleosomes
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Which of the following grows on minimal media only if the minimal media is supplemented?
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auxotroph
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by weight, chromatin consists roughly by...
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1/3 DNA, 1/3 histones, and 1/3 non histones
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Assume that a transition mutation results in an amino acid substitution in the resulting polypeptide. What level of protein structure might be affected as a result?
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primary, secondary, tertiary, and quaternary structure.
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In DNA, the 300 angstrom fiber is formed into structural loops. Responsibility for this function appears to lie with
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certain nonhistone proteins
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that histones have changed so little throughout evolution emphasizes the importance of their contribution to chromatin structure.
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True
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Which scientist(s) proved that DNA was the molecule of heredity, and responsible for transformation?
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Avery, MacLeod, and McCarty
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Crossing over occurs during
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Prophase 1
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How many replication forks depart from an origin of replication?
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two
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During complementary base pairing, enzymes join the base's nucleotide to the preceding nucleotide by a(n) ___ bond.
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phosphodiester
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Excision repair corrects DNA by
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detecting, removing, and replacing damaged or incorrect nucleotides in a single strand of DNA
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___ bonds are responsible for the chemical affinity between complementary nucleotides.
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hydrogen
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One of the functions of a centromere is to contribute to proper chromosome segregation. The other function is to....
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hold sister chromatids together
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Examination of the rhodopsin gene family provides evidence for gene evolution by
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duplication and divergence
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A missense mutation is one that creates a premature stop codon.
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False
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The two chromatids of each replicated chromosome must separate from one another and segregate during ...
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both mitosis and meiosis 2
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Which of the following is not usually seen when a cell loses telomerase activity?
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many normal somatic cells gain the ability to divide indefinitely.
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Eukaryotic chromosomes have evolved special structures at the ends of chromosomes to ensure the replication of the two ends of linear chromosomes. These structures are called...
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telomeres
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Intercalating agents such as ethidium bromide function as mutagens to...
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fit between stacked bases and disrupt replication
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DNA replication occurs through a ___ process
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semiconservative
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The condition sickle cell anemia is due to...
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point mutation
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chromosome banding patterns can be used for which of the following?
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to analyze chromosomal differences between species, to locate gene, and to reveal the cause of certain genetic diseases.
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The first level of compaction of DNA consists of ...
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DNA winding around histones to form small nucleosomes
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Without ___ regions on the DNA during recombination, gene conversion could not occur.
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heteroduplex
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In eukaryotic cells, replication proceeds from ___ origin(s) or replication.
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many
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DNA topoisomerase supercoils DNA to get it out of the way of DNA polymerase.
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False
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A heritable change in DNA base sequence is called a...
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mutation
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What would happen if a transposon were to "jump" into the origin of the bacteria genome?
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transposon would inactivate the origin; no DNA replication possible.
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Which scientists provided X-ray structure pictures of DNA?
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Franklin and Wilkins
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Which of the following is a condensed single X chromosome seen in the nuclei of somatic cells of female mammals.
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Barr body
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From DNA research, sites of transcription and therefore most of the genes along the length of the chromosome appear to be found in...
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euchromatin
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Alkylating agents such as ethylmethane sulfate (EMS) funtion as mutagens to...
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add ethyl or methyl groups
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The consequence to a bacterial cell of a mutation that inactivated the enzyme that methylates the A of the sequence GATC in newly made DNA would be ....
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failure to distinguish old and new DNA during mismatch repair
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cohesins are a multisubunit protein complex that functions to...
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hold sister chromatids together
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the polarity of DNA synthesis is ...
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5' to 3'
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Alternative resolutions of the Holliday intermediate are responsible for whether or not crossing over occurs.
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True
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A bacterium is found that is resistant to the antibiotic gentamicin. The bacterium was isolated in a hospital where patients were routinely given gentamicin for a variety of infection. What was the pressure that selected for this resistant population?
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presence of gentamicin in the environment
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Unequal crossing over can result in...
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a creation of deletions and duplications
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Which of the following is an example of a recombinant DNA molecule?
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a genomic fragment of human DNA ligated to a bacterial plasmid vector
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Pyrosequencing is possible because the addition of a particular base to a sequence is detected by the emission of light.
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True
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How many genes have been estimated to be in the human genome?
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20,000-30,000
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The highest resolution map of a genome can best be generated from...
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sequence analysis
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An organisms' genome is
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the DNA content and sequence of all of its genes
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In repressor quenching, a repressor protein binds directly to an activator protein.
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True
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Trancription in prokaryotes and eukaryotes is similar in that..
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both are regulated by atachment of proteins to DNA adjacent to the gene being transcribed
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Zinc-finger peptide motifs are responsible for what aspect of protein function?
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DNA binding
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Trans-acting proteins that influence the transcription are commonly referred to as
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transcription factors
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What information cannot be determined from the DNA sequence of a cDNA clone?
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sequence of the promoter
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A cis-acting DNA sequence that modulates the basal rate of transcription of a gene is termed a(n)
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enhancer
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In sanger sequencing , what causes DNA synthesis to terminate at a specific base?
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nucleotide triphosphates that lack a hydroxyl
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PCR cannot be successfully performed without..
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at least some sequence information about the region to be amplified
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What charge does DNA have, and what gives it this charge?
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negative phosphates
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RNA polymerase 1 synthesizes ___ using a DNA template.
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rRNA
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mRNA molecules are transcribed by...
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RNA pol 2
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A plasmid has amp and lacZ genes for ampicillin resistance and beta-galactosidase, respecitvely. There is a single EcoRI site within the lacZ gene. The EcoRI-cut plasmid is combined with a DNA fragment that has also been cut with EcoRI. Cells that contain the plasmid with the insert will be..
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ampicillin resistant and white if grown on X-gal
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In gel electrophoresis of DNA, fragments move at different rates because they have different..
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sizes
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The ___ is the cis-acting DNA sequence that serves as the binding site for RNA polymerase
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promoter
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The leucine zipper motif functions to...
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mediate the physical association of two poplypeptides
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Modern geneticists define an allele as any variation in the DNA sequence of a locus.
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True
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Which of the following is NOT a use of the two-color DNA microarray technique?
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Allows identification of a gene's promoter
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The promoter of nearly all eukaryotic genes contain a(n)
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RNA polymerase binding region, TATA box, and initiation site
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Which of the following is NOT a mechanism employed by repressor proteins to decrease transcription of a specific gene?
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The repressor binds to RNA polymerase 2, blocking its ability to associate with promoter element.
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Restriction enzymes were named because they restrict...
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the capacity for viral growth
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How do bacteria protect their own DNA from the restriction enzymes they produce?
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Digestion is blocked by methyl groups added to recognition sequences in their DNA.
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A transcription factor that increases initiation of transcription by associating with an enhancer element is a(n)
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activator
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Proteins that consist of two identical polypeptide subunits are classified as..
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homodimers
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The gene products encoded by trans-acting elements perform their function by...
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associating with regulatory sequences distant from the gene from which they were transcribed.
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The lacZ gene is sometimes included in a cloning vector. What does it encode?
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detectable enzyme that is not produced if the gene is interrupted by an insert
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Most decisions controlling the amount of gene products synthesized are made during
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initiation of transcription
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RNA interference is a process that regulates gene expression at the time of transcription
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False
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Which of the following is NOT involved in RNA interference processes?
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RNA polymerase 1
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Which of the following would NOT have its gene represented in a cDNA library from red blood cell precursors?
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an rRNA
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Hypercondensation of heterochromatin results in..
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DNA replication
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DNA regions that are transcriptionally silences by hypercondensation have often undergone a modification of their cytosine residues termed...
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methylation
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Antibiotic resistance genes are often used as selectable markers in vectors.
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True
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A genomic library is a..
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collection of DNA fragments from an organims, inserted into vectors
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The ___ is the repeating structural unit of chromatin, consisting of approximately 200 base pairs of DNA and associated histone proteins.
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nucleosome
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Hybridization is the covalent binding of two complementary DNA strands.
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False
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Where do restriction enzymes come from, and what is their normal physiological function?
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Bacteria produce them to protect against viral invasion
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DNA sequences that serve as binding sites for proteins regulating transcription and are often found adjacent to a gene are said to be..
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cis-acting
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reverse transcriptase is an enzyme made by...
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retroviruses
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If a single DNA molecule is amplified by PCR, how many DNA molecules will there be after six cycles?
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64
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___ are transcription factors that decrease transcriptional activity by associating with specific enhancer elements or activator proteins.
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repressors
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