Concept explainers
a.
To determine: The presence of linkage between genes in a three-point cross between the parental genotypes +/+ · +/+ · +/+ x p/p· v/v · b/b.
Introduction: A cross between a triple heterozygote parent and a homozygous recessive tester with triply recessive alleles is called a three-point testcross. With the help of a three-point testcross, one can determine the linkage between three or more genes and gene order.
b.
To Draw: A genetic map showing distances between p, v, and b genes in map units.
Introduction: The map unit (m.u.) also referred to as a centimorgan (cM) helps to evaluate the physical distances between genes that are located on the same chromosomes (genetic linkage). The two loci with 1% of recombination explain that they are 1 map unit apart on a genetic map.
c.
To determine: The interference in a three-point cross between the parental genotypes +/+ · +/+ · +/+ x p/p· v/v · b/b.
Introduction: The crossovers hinder each other in an interaction known as interference. The gene interference determines whether crossovers are dependent or independent from each other. It is determined by calculating the coefficient of coincidence (c.o.c.). As, the interference = 1 - coefficient of coincidence (c.o.c.).
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Introduction to Genetic Analysis
- Show the cross between a plant which is tall and purple, heterozygous for both traits AND a plant which is short and purple; heterozygous for purple flowers. Use the dihybrid template printout from above for this cross. Insert your picture by clicking on the picture frame and ensure that your picture includes your name.arrow_forwardConsider two maize plants:a. Genotype C/c m ; Ac/Ac+, where cm is an unstable allele caused by a Ds insertionb. Genotype C/c m, where cm is an unstable allele caused by Ac insertionWhat phenotypes would be produced and in what proportions when (1) each plant is crossed with a basepair-substitution mutant c/c and (2) the plant in part a is crossed with the plant in part b? Assume that Ac and c are unlinked, that the chromosome-breakage frequency is negligible, and that mutant c /C is Ac+.arrow_forwardWhat is/are the phenotypes of the recombinant offspring of the F2generation?a. red eyes, long wingsb. white eyes, miniature wingsc. red eyes, long wings and white eyes, miniature wingsd. red eyes, miniature wings and white eyes, long wings [Answer the multiple-choice questions based on the following experiment:P generation: True-breeding flies with red eyes and long wings werecrossed to flies with white eyes and miniature wings. All F1 offspringhad red eyes and long wings.The F1 female flies were then crossed to males with white eyes and miniaturewings. The following results were obtained for the F2 generation:129 red eyes, long wings133 white eyes, miniature wings71 red eyes, miniature wings67 white eyes, long wings]arrow_forward
- Consider two maize plants:a. Genotype C/cm ; Ac/Ac+, where cm is an unstableallele caused by a Ds insertionb. Genotype C/cm, where cm is an unstable allele causedby Ac insertionWhat phenotypes would be produced and in whatproportions when (1) each plant is crossed with a basepair-substitution mutant c/c and (2) the plant in part a iscrossed with the plant in part b? Assume that Ac and care unlinked, that the chromosome-breakage frequencyis negligible, and that mutant c /C is Ac+.arrow_forwardConsider the first category of test-cross offspring shown in figure 8.2 (+b, LS). Consider also that the parents of the heterozygous female flies in the test cross had the following genotypes: bb, SS, and +, LL. A. What would be the physical phenotype of these flies? B. If PCR was conducted with the DNA of one of these flies using the primers for the molecular marker, what would be the appearance of the bands on an electrophoresis gel with the PCR products? C. If the gene for black body and the locus for the molecular marker (L long or S short) were unlinked, what proportion of the test-cross progeny would be black flies that are heterozygous for the molecular marker? What proportion would be flies with normal body color, which are homozygous for one form of the molecular marker? D. If the gene for black body and the locus for the molecular marker were linked, how would the proportion of flies be different?arrow_forwardTo build a genetic map, how many types of crosses will be required to perform if you have three genes to map? Explain.arrow_forward
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- Drosophila females heterozygous for three recessive mutations, a, b, and c , were crossed to males homozygous for all three mutations.The cross yielded the following results: in the image Q. Construct a linkage map showing the correct order of these genes and estimate the distances between them.arrow_forwardDraw a simplified schematic for Heidelberg screening to identify zygotic genes.arrow_forwardThe first task in mapping genes in three-point testcross is to determine their order on the chromosome and then to determine the locations of the cross overs. There are two ways, one can determine which gene is in the middle. Describe both the methods that explains how one would determine the middle locus- You can use three genes A, B, and C. You can decide whatever phenotype each gene encodes.arrow_forward
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