Florida Atlantic University PCB 3063 Genetics Exam Questions COMBINED: Contains Over 200 Questions and Answers.

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Chapter 7 ­ Linked genes occasionally switch from one homologous chromosome to the other through which process? - Crossing over ­ Gametes that contain only the original combinations of alleles ... present in the parents are called _____ gametes. - nonrecombinant ­ Chromosome maps constructed using distances along the chromosome (often expressed as numbers of base pairs) are called _____ maps. - physical ­ The degree to which one crossover interferes with additional crossovers in the same region is the -interference ­ Linked genes are those that ________. - are located close together on the same chromosome ­ The ratio of the observed number of double crossovers to the expected number of double crossovers is the - coefficient of coincidence ­ A three-point cross is a - testcross for three genes ­ Chromosome maps constructed using recombination frequencies are called _____ maps. - genetic ­The number of recombinant progeny divided by the total number of progeny is known as the _____ frequency. - recombination ­ One centiMorgan equals how many map units? - 1 ­ When one wild-type allele and one mutant allele are found on each chromosome ( ), the genes are said to be in _____ configuration - repulsion ­ Genes located close together on the same chromosome belong to the same _____ group. - linkage ­ A particular set of linked alleles is called a - haplotype ­ In a somatic cell hybridization experiment, one cell line retained human chromosomes 4, 9, 15, and 21, a second cell line retained human chromosomes 2, 9, 13, and 21, and a third cell line retained human chromosomes 4, 13, 19, and 21. Thefirst two cell lines produce the product of the gene whose chromosome location is being established, while the third cell line doesn't produce the gene product. What chromosome is this gene most likely located on? - 9 ­ When two wild-type alleles are found on one chromosome and two mutant alleles are found on the homologous chromosome ( ), the alleles are said to be in ____configuration. - coupling ­ A three-point testcross is often used to - efficiently map genes ­ Genes A and B are linked. When a single crossover occurs in an individual with genotype Aa Bb, what proportion of the resulting gametes will be recombinant? - ½ ­ One map unit equals what percent recombination? - 1 ­ A method for finding which human chromosome a gene may be located on that involves fusing human cells with rodent cells such as mice cells is called what? - Somatic-cell hybridization ­ Single-nucleotide polymorphisms (SNPs) are - positions where individuals vary at a single DNA base ­ Gametes that contain new combinations of alleles not present in the parents are called _____ gametes. - recombinant ­ A chi-square test of _____ can be used to determine if linkage occurs between genes. - independence ­ Harriet Creighton and Barbara McClintock obtained evidence that intrachromosomal recombination was the result of physical exchange between chromosomes by studying which organism? - Corn (maize) ­ Gametes that contain new combinations of alleles not present in the parents are called _____ gametes. - recombinant ­ In deletion mapping, an individual who is homozygous for a recessive mutation within a gene that is being mapped is often crossed to - an individual who is heterozygous for a deletion ­ Gametes that contain only the original combinations of alleles present in the parents are called _____ gametes.- nonrecombinant ­ The genotype AB/ab means that - alleles A and B are on the same chromosome ­ In somatic-cell hybridization experiments to map the chromosomal location of human genes, a human cell line is crossed to what other type of cell line? - A rodent cell line ­ In a three-point cross, the double-crossover progeny can be identified because they - are the least numerous progeny. ­ Which of the following statements is FALSE? - In humans, recombination rates are about the same for males and females. ­ Genes A and B are linked. When no crossing over occurs in an individual with genotype Aa Bb, what proportion of the gametes will be recombinant? - 0 ­ The degree to which one crossover interferes with additional crossovers in the same region is the - interference ­ Recombination hotspots in humans are - often found near but not within active genes. ­ A three-point cross is a - testcross for three genes ­ A chi-square test of _____ can be used to determine if linkage occurs between genes - independence ­ When one wild-type allele and one mutant allele are found on each chromosome ( ), the genes are said to be in _____ configuration - repulsion ­ A two-strand double crossover between two linked genes produces what types of gametes? Assume that both crossovers occur on the same two chromatids. - Nonrecombinant only ­ Lod (logarithm of odds) scores are used to determine the probability that two genes are linked ­ The ratio of the observed number of double crossovers to the expected number of double crossovers is the - coefficient of coincidence­ Assume loci A and B are completely linked with no crossing over. What proportion of the progeny will have genotype Aa Bb? - ½ ­ Intrachromosomal recombination (recombination between genes on the same chromosome) occurs where in mitosis and/or meiosis? -Prophase I of meiosis ­ The following testcross produces the progeny shown: Aa Bb x aa bb → 10 Aa Bb, 40 Aa bb, 40 aa Bb, 10 aa bb. What was the arrangement of the genes in the Aa Bb parent? - Repulsion ­ ______ functions relate recombination frequencies to positions of genetic loci on a chromosome. - Mapping ­ For single crossovers, the frequency of recombination is half the frequency of crossing over because - each crossover takes place between only two of the four chromatids of a homologous pair. ­ Which of the following best describes the difference between recombination rates in humans and chimpanzees? - In both chimpanzees and humans, there are recombination hotspots, but the location of the hotspots often differ between the two species. ­ Two genes have been both assigned to chromosome 12 by somatic-cell hybridization analysis. However when lod-score analysis is performed, the genes appear to be assorting independently. The most likely reason for the different results is that - the two genes are far apart on chromosome 12 ­ Genomewide association studies are used to - locate genes by examining the nonrandom association between a trait and many genetic markers. ­ The following testcross produces the progeny shown: Aa Bb x aa bb → 10 Aa Bb, 40 Aa bb, 40 aa Bb, 10 aa bb. What is the percent recombination between the A and B loci? - 20% ­ Genetic _____ are variable genes or DNA sequences with easily observable allelic differences. - markers ­ The following testcross produces the progeny shown: Aa Bb x aa bb → 40 Aa Bb, 10 Aa bb, 10 aa Bb, 40 aa bb. What was the arrangement of the genes in the Aa Bb parent?- Coupling ­ In a three-point cross, the nonrecombinant progeny can be identified because they are - the most numerous progeny ­ Interchromosomal recombination (recombination between genes on different chromosomes) occurs where in mitosis and/or meiosis? - Anaphase I of meiosis ­ Consider the following cross: Aa Bb x aa bb. If these genes assort independently, what proportion of the progeny will have genotype Aa Bb -¼ ­ Since the location of recombination hotspots differ in humans and chimpanzees, recombination hotspot locations likely can be changed through evolution. Assume that some type of evolutionary event results in the establishment of a new human recombination hotspot in the middle of a particular haplotype on chromosome 4. Over time, what would likely be the effect of this new hotspot on the haplotype? - The haplotype will be disrupted, and some alleles will no longer be in linkage disequilibrium in future times ­ Assume loci A and B are completely linked with no crossing over. What proportion of the progeny will have genotype Aa Bb? - ½ - When genes violate Mendel's second law, they are said to: -A and B. fail to assort independently. be linked. ­ Since linked genes violate Mendel's second law, a typical dihybrid cross with them would show: ­ something other than a 9:3:3:1 ratio ­ Since linked genes segregate together, they would be expected to ­ not assort independently ­ Linked genes do not segregate together 100% of the time, due to the phenomenon known as: ­ crossing over ­ Crossing over results in linkage being incomplete and takes place during ­ None of the above ­ While linkage can, in theory, be identified in any well-constructed cross, it is easiest to demonstrate it with ­ a dihybrid cross ­ When there is no crossing over, meiosis produces four nonrecombinant haploid gametes. A single crossover produces: ­ two recombinant haploid gametes and two nonrecombinant haploid gametes ­ Recombination frequency is simply ­ the number of recombinant offspring divided by the total number of offspring ­ When two dominant alleles or two recessive alleles are linked to each other it is known as­ coupling [Show More]

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