Biology 3451 Exam I F'16

BIOL 3451 Genetics Fall 2016 Exam I Name:________________________________ Signature:___________________________ The first solid scientific/experimental evidence that suggested that DNA was the molecule central to the “genetic material” was obtained by: Frederick Griffith. Avery, McCarty and MacLeod. James Watson and Francis Crick. Thomas Morgan. Cohen and Boyer. Enzymes were discovered in bacteria in the 1970s that were able to cut viral/bacteriophage DNA molecules at specific sites/sequences. These enzymes are called: exonucleases. recombinases. assimilases. restriction endonucleases. site-specific recombinases. The copies of chromosome 1 that you inherited from your mother and your father would be best described as being: a tetrad. diploid. synaptic. homologous. a dyad. A cell that is 2n = 46 replicates its DNA and undergoes the process of meiosis. If all goes correctly, the two “cells to be” (daughter cells after karyokinesis) at the end of anaphase I will each have: 46 chromosomes. 23 chromosomes. 92 chromosomes. 23 pairs of chromosomes. 92 chromatids. The larger arm of a eukaryotic chromosome is referred to as the: minor arm. recessive arm. P arm. short. Q arm. During meiosis, the process of genetic recombination occurs during: anaphase I. metaphase I. metaphase II. prophase I. prophase I and II. Which of the following processes is considered a reduction division in the context of genetics? mitosis meiosis I meiosis II All of the above are considered reduction divisions because each reduces the DNA content of the resultant cells by half. None of options a-c are considered reduction divisions because each doubles the cell number after cytokinesis. During the short time that would constitute metaphase I, one each of the two sister chromatids that in turn make up each of the two homologous paired chromosomes are connected to each other by: centromeres. terminal chiasmata. centrioles. synaptonemal complexes. centrosomes In eukaryotic cells the specific process of partitioning the genetic material into daughter cells (nuclear division) is most accurately classified as: mitosis. karyokinesis. cytokinesis. anaphase. S phase. The protein structures that are assembled in the regions between homologous chromosomes during prophase of meiosis I are called: synaptonemal complexes. centromeres. chiasma. kinetochores. dyads. Chromosome dyads migrate to opposite poles of the cell during: telophase. anaphase I. telophase I. anaphase. anaphase II. During mitosis and meiosis in animal cells, the spindle apparatus originates from a specialized region/complex called the: centromere. nucleosome. synaptonemal complex. chiasma. centrosome. During mitosis of mammalian cells, the chromosomes are connected to the spindle apparatus through specialized structures called: telomeres. centrioles. centromeres. kinetochores. basal bodies. During the actual process of genetic recombination a specialized structure is assembled between the two chromosomes at the point of the genetic exchange. This structure is called a/an: tetrad complex. centromere. chiasma. kinetochore. dyad. A mammalian somatic cell you are studying has not divided in several days and is unlikely to divide in the next few days either. It is most likely in what phase of the cell cycle at this moment? G0 G2 S phase mitosis cytokinesis During which of the following phases of meiosis does the cell carry out the process referred to as homology search? mitosis prophase meiosis prophase I meiosis prophase II karyokinesis Answers “a”, “b” and “c” are all correct. A cell is observed to have 23 tetrads during metaphase I. A somatic cell of this species almost certainly has ______ chromosomes. 23 46 69 92 None of the above is a likely correct number of chromosomes for such a cell. Alfred Russel Wallace, who had not heard of Mendel’s experiments, believed that the offspring of two parents should be a blend of their parents’ phenotypes (e.g. red x white would give pink, pink x white would give lighter pink). Had he been correct, Mendel should not have observed discrete phenotypes in peas (only “completely/full” purple or very white flowers) in the “world of peas” but would have observed a range of available colors and a phenomenon now called: complete dominance. averaging. continuous variation. natural selection. selectional blending. When you have a simple dominant/recessive relationship between two alleles at a locus it is generally impossible to tell the PP individuals from the Pp individuals based upon visual analysis alone. A simple but accurate approach to distinguish PP individuals from Pp specimens is to perform a/an: monohybrid cross. dihybrid corss. testcross. Punnett square analysis. linkage analysis. When planning an experiment, it is important to estimate the amount of data that should be collected in order to have a reasonable chance of getting “statistically significant” results. A key factor in making this calculation involves the degrees of freedom for your experiment. In the case of a simple dihybrid cross of two unlinked loci that each behave in a completely dominant/recessive fashion this would be: one. two. three. four. five. You have chosen to perform genetics experiments with a model organism that commonly only produces two offspring, reproduces only once per year and is rather expensive to maintain (feed). Regrettably due to funding cuts you are unable to perform the number of crosses that you originally told Mendel (your major professor) that you would carry out. However, you still believe that you have sufficient data to adequately support the hypothesis that he would like to present at the next meeting of the Austrian Society of Geneticist Monks (and which you would defend as your dissertation). To demonstrate your point that the data do provide sufficient support to the theory you would be best advised to perform a/an ______ of your data. Punnett square analysis fork analysis. Chi-square analysis. null analysis. P square analysis It turns out that when Mendel was promoted to Abbot he didn’t stop performing genetic crosses. He simply changed plant types and started a new book, which has now been found hidden in the attic of the abbey. This newly discovered book reveals that he had crossed red snapdragons with white ones, obtained all pink F1 and the F2 were 25% red, 50% pink and 25% white. This appears to be the only experiment recorded in the book, which ends with a notation about the possibility that the results are a sign from God intended to emphasize to him how important it was to focus entirely on his new and important duties. While this is a possibility, it might also be argued that God simply wanted to teach him about the phenomenon we now know as: codominance. pleiotrophy. incomplete dominance. multifactor inheritance. partial penetrance The pattern of inheritance shown is the pedigree below is most consistent with the allele under study being: autosomal recessive. autosomal dominant. X-linked recessive. X-linked codominant. autosomal codominant.\ 828675-4762500205740016611600038862006096000 The pattern of inheritance shown is the pedigree below is most consistent with the allele under study being: autosomal recessive. autosomal dominant. X-linked dominant. X-linked recessive. autosomal codominant. 457200011430000685800000 A plant species under study has both tall and short varieties. The plant makes a growth hormone (made by enzyme A) in the leaves that is transported (by transport protein B) to the stems and acts to make them elongate. A true-breeding Tall plant is crossed with a second plant homozygous for the recessive, nonfunctioning, allele of the transport protein but homozygous wild-type genotype for enzyme A. What fraction of the F2 offspring will be expected to be dwarf? 1/16 3/16 4/16 7/16 9/16 An artic hare is found to have snow white fur in the winter. However, the same animal is found to be a mottled brown color during the summer months. This is best explained as an example of: continuous variation. incomplete dominance. pleiotrophy. codominance. environmental effect. The mutant allele for Huntington disease, and the ones for several other diseases since, was cloned and sequenced. Comparisons of the mutant and wild-type sequences revealed the difference to be: a single nucleotide difference (point mutation). a translocation that fused two genes in an inappropriate fashion. a deletion in an important regulatory region for the affected gene. an increase in the number of repeats of a trinucleotide sequence. None at the sequence level, leading to the discovery of epigenetics. Myotonic Dystrophy, Fragile X, and Huntington disease are examples of human genetic diseases that exhibit earlier ages of onset and/or an increased severity in afflicted members of each successive generation in families in which the mutant alleles are segregating. These are both examples of genetic diseases which exhibit: partial penetrance. incomplete dominance. genetic imprinting. genetic anticipation. delayed onset phenotypic expression. The Bombay phenotype involving a locus affecting/controlling human blood type is considered to be a classic example of: allelic complementation. incomplete dominance. pleiotrophy. codominance. epistasis. If one crosses two yellow coat mice one obtains offspring that are yellow and agouti in a 2/3 and 1/3 proportion, respectively—not in quarters or even 16ths as might be expected. The explanation for this result involves: experimental error. incomplete dominance. partial penetrance. lethal alleles. sex linkage. The expression of the MN group of human blood antigens is an example of: allelic complementation. incomplete dominance. pleiotrophy. codominance. epistasis. In humans and many other eukaryotic species, extensive methylation of CpG dinucleotides within and around a gene cause the gene to be turned off. The use of this modification of the DNA molecule as a mechanism to turn off genes in a heritable fashion turned out to be the explanation for a genetic phenomenon we now call: genetic anticipation. epistasis. genetic imprinting. infectious inheritance. environmental effect. An “AA” individual is crossed with an individual with an “aa” genotype. The F2 offspring include 85% of the “A” phenotype and 15% of the “a” phenotype. With respect to the “a” phenotype, this could be a good example of: incomplete dominance. codominance. simple dominant/recessive alleles. epistasis. partial penetrance. Hemizygous would be appropriate to describe: haploid gametes. genes on the mammalian X chromosome. genes on the Z and W chromosomes. cells at the end of meiosis I. cells with an abnormal chromosome number due to an error in meiosis. Colorless (white) precursor #1 is converted to yellow intermediate #2 by enzyme A (encoded by the “A” locus). Intermediate #2 is converted to green-colored product #3 by enzyme B (encoded by the “B” locus). An AABB plant is crossed with an aabb plant to give AaBb F1 individuals. What would be the F2 phenotypic ratio? 9:7 9:3:3:1 9:6:1 9:3:4 12:3:1 Prader-Willi and Angelman syndromes are examples of genetic diseases where the mutant allele of a gene is only expressed as a damaging phenotype if it is inherited from a specific parent (P-W from father, Angelman from mother). The expression of alleles in these cases are examples of: partial penetrance. incomplete dominance. genetic imprinting. genetic anticipation. positional effects. You have crossed a Holstein cow and bull, both with very good genetic backgrounds for high level milk production, and have produced two nice male calves. You patiently wait until these youngsters are two years old and still the milk production from the two remains essentially zero. What went “wrong” with the expression of this trait? sex limited. incomplete dominance. pleiotropy. sex influenced. partial penetrance. It has been observed that in some cases, as evidenced by studies involving chromosome/gene translocations, the physical location of a gene/allele in relation to other genetic material can influence its expression. This phenomenon is called: conditional expression. penetrance. expressivity. position effect. epistasis. You are conducting 3 point crossover experiments and notice that, although often your results fall within the expected range when comparing double and single crossover frequencies in each case, in some cases the number of double crossovers is fewer than expected while in others the number of double crossovers is greater than predicted by the related number of single crossovers. The phenomenon you have discovered is referred to as: incomplete dominance. interference. continuous variation. chiasmatic interaction. The coefficient of coincidence. Somatic cell hybridization was a procedure developed in the 1960s to: study gene expression in mice. identify factors controlling the process of mitosis in human cells. map human genes to specific chromosomes. study chromosome interference in mammals. measure crossover rates between homologous mouse and human chromosomes. Linkage maps of chromosomes are measured/drawn in what units? centiMorgans nucleotides centimeters recombination event units (REUs) centromeres Sister chromosome exchanges are recombination events that occur between homologous chromosomes and are often the result of: exposure of the cell to DNA damaging agents. asexual reproduction processes. interspecies reproduction leading to allopolyploid offspring. asyntenic crossover events. reciprocal crossover events. An example of a group of loci commonly found to be widespread in the genomes of higher eukaryotes and which are very often quite polymorphic in populations and have been used extensively in mapping/linkage studies (as well as identify, parentage and genetic diversity studies) are: organelle encoded gene loci. CEN sequences. telomeric sequences. microsatellites. SCEs. The process of transferring genetic information from one bacterium to another via the release of “naked” DNA into the medium (often as the result of cell death), the subsequent uptake of this DNA directly from the medium by a living cell, followed by incorporation/recombination of the donor DNA fragment with the recipient bacterium’s genetic material, is called transduction. transformation. conjugation. segregation. cotransformation. The physiological state which allows a bacterial cell to take up foreign DNA into the cell and subsequently incorporate a strand of the DNA into its own chromosome is called: transformation. conjugation. transduction. recombination. competence. An Hfr strain of E. coli would likely exhibit: a high rate of gene transfer by conjugation. a high level of competence. a high susceptibility to transduction a strong tendency to accept lysogenic bacteriophage. resistance to multiple antibiotics. An E. coli strain that requires growth media to be supplemented with methionine and leucine would be termed a/an: prototroph. autotroph. ditroph. auxotroph. chemotroph. The term that best describes those genetic elements that can either replicate independently or as part of the bacterial chromosome is: prophage. lysogens. plasmids. episomes. transposable elements. An individual (such as some individuals of the nematode C. elegans) possesses both sexual systems (male and female). This individual would be best described as: prokaryotic. disexual. hermaphroditic. asexual. isogametic. In humans, 45,X0 individuals are said to suffer from: sexual trisomy. Klinefelter syndrome. Turner syndrome. Huntington disease. fragile X syndrome. Which of the following individuals would NOT be considered heterogametic? ZW bird. XY human X0 insect All of the above are heterogametic. None of the above is heterogametic. A male bird would be expected to be: XX. XY. XO. ZZ. ZW. Portions of the human Y chromosome share sequence homology with portions of the human X chromosome. These regions are called: SRYs. PARs. TDFs. MSYs. heterochromatin.