If 50% recombination occurs (two parental types and two recombinant gametes), th
ID: 164840 • Letter: I
Question
If 50% recombination occurs (two parental types and two recombinant gametes), the transmission is then indistinguishable from independently assorting genes. Yes No Assume that a cross is made between AaBb and aabb plants and that the offspring occur in the following numbers: 1060 AaBb, 480 Aabb, 520 aaBb, 940 aabb. These results are consistent with _____ sex-linked inheritance with 30 percent crossing over linkage with approximately 33 map units between the two gene loci linkage with approximately 30 map units between the two gene loci independent assortment 100 percent recombination Methods for determining the linkage group and genetic map in humans involve _____ DNA markers twin spots and tetrad analysis tetrad analysis and bromodeoxyuridine zygotene and pachytene DNA synthesis and classical analyses In a population of 100 individuals, 49 percent are of the NN blood type. What percentage is expected to be MN assuming Hardy-Weinberg equilibrium conditions? 9 percent 21 percent 42 percent 51 percent There is insufficient information to answer this question. Albinism is an autosomal recessive trait in humans Assume that there are 100 albinos (aa) in a population of 1 million. How many individuals would be expected to be homozygous normal (AA) under equilibrium conditions? 100 10,000 19, 800 980, 100 999, 900 Which method is often used to analyze proteins and nucleic acids by physical separation when estimating genetic variation in populations? electrophoresis centrifugation absorption spectrophotometry fluorometry in situ hybridizationExplanation / Answer
Please find the answers below and reasons in parentheses:
Part 1: False (according to Mendelian pattern of inheritance and modern advances in genetics, if two or more genes are more than 25cM apart, they will undergo recombination. If a recombination event takes place between two genes, the offspring will display either the parental type features owing to the presence of dominant genes or it shows a mixed character owing to presence of two types of alleles for a phenotypic character. In both the cases, these genes do follow independent assortment and normal patterns of Mendel's inheritance.)
Part 2: Choice B (The total number of recombinant classes are 480+520 or 1000 and the total population is 3000. This gives the total recombination between the two alleles is 1000*100/3000 OR nearly 33%. Thus the alleles are linked and the map distance is nearly 33cM)
Part 3: Choice D (The differential arrangement of zygotene and pachytene chromosomes help in physical determination and evaluation of number of linakge groups and genetic mapping respectively by morphological and physical analytical methods.)
Part 4: Choice B (Since the percentage of NN types is 49%, the allelic frequency of N is given by square root of 49% or 0.7. Since the Hardy-Weinber law states that the sum of allelic frequencies is unity, the allelic frequency of M will be 1-0.7 or 0.3 or 9%. This also states that the percentage of MN will be 0.7*0.3 or 0.21 or 21%)