Bio 198 Final Exam Questions and Complete Solutions

Complementation analysis Used to distinguish mutations in the same gene from mutations in different genes Phenotypic ratios Everything is a form of the 9:3:3:1 ratio. You have to figure out why the deviation exists (if it does exist). Genetic Dissection The point of a genetic dissection is to determine the order of a biosynthetic pathway. The mutation that is supported by no supplemental media is the last mutation in the pathway. Epistasis Genes interact with each other and thereby affect expression of each allele. Causes deviations in phenotypic ratio. Incomplete penetrance The phenotype of an organism does not match its genotype. Similar to variable expressivity, in which the same genotype may produce a levy of different phenotypes. Allelic series The main idea is that one phenotype (such as coat color) may have a lot of different alleles. Depending on which set of alleles you have, one's phenotype varies. Parental ditype Tetrad contains spores with same genotype as parent Nonparental ditype Occurs from independent assortment of nonlinked genes (genes are on separate chromosomes). Spores in tetrad are all different from parent Tetratype Occurs from a crossover event. Contains 2 parental spores and 2 nonparental spores Linked genes/tetrad analysis (unordered tetrad) Frequency of PDTTNPD - NPD requires a double crossover event to happen, which is unlikely Genetic linkage analysis unordered tetrads Recombination frequency = number of recombinants/total number of progeny. Tetrad recombinant frequency = ((1/2*TT)+NPD)/total tetrads Indications of genetic linkage Compare the observed frequencies of gamete genotypes with the frequencies expected under independent assortment (chi-squared analysis). Get expected by determining expected percentages of each gamete or genotype and multiplying by total number in the sample. Remember that in this case