If two genes on the same chromosome, A and B, are completely linked and no crossovers can occur between them, how many phenotypic combinations would be visible in the offspring from a testcross between a heterozygous female (AaBb) and a homozygous recessive male (aabb)? Explain. A. 1 B. 2 C. 4 D. 8

If two genes on the same chromosome, A and B, are completely linked and no crossovers can occur between them, how many phenotypic combinations would be visible in the offspring from a testcross between a heterozygous female (AaBb) and a homozygous recessive male (aabb)? Explain. A. 1 B. 2 C. 4 D. 8

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Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter6: Cytogenetics: Karyotypes And Chromosome Aberrations

Section: Chapter Questions

Problem 16QP: Assume that a meiotic-nondisjunction event causes trisomy 8 in a newborn. If two of the three copies...

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Explain what nondisjunction is, and give two examples of phenotypes that can result from it.
Assume that a meiotic-nondisjunction event causes trisomy 8 in a newborn. If two of the three copies of chromosome 8 are absolutely identical, at what point during meiosis did the nondisjunction event take place?
11:52 In the fruit fly, vestigial wings and hairy body are produced by two recessive genes located on different chromosomes. The normal alleles, long wings and hairless body, are dominant. Suppose a vestigial-winged hairy male is crossed with a homozygous normal female. What types of progeny would be expected? If the F1 generation from this cross are permitted to mate randomly among themselves, what progeny would be expected in the F2? Show complete genotypes, phenotypes and ratios for each generation. 7. Other problems: How do you know the genotype of organisms with a dominant phenotype? Is it homozygous or heterozygous? A pea plant exhibits a purple color, but you are unsure of its genotype. With what could you cross this plant to determine its genotype? Show all of 8. your work for the cross. What is this type of cross called? Incomplete dominance: Genes code for the production of specific proteins, many of which are enzymes. Different alleles at a locus code for alternative forms…
Explain why heterozygotes for inversions and translocations have low fertility.
25. a)What is “dihybrid cross”? b) Consider two traits color and height. For color, let Y=yellow be dominant over y=green; for height, let T=tall be dominate over t=short. i. Set up the P1 generation ii. enumerate the possible gametes in the sex cells iii. Put the possible gametes along the top and sides of a Punnett square. iv. Hence, or otherwise, find a) the proportion (in percentage) of the F1 are yellow and tall with genotype YyTt b) The probability of obtaining, the genotype YyTt
3) A. How are the following proteins involved in cell division: condensing, cohesin, kinetochore complex, tubulin? B. Why does phenotype not always reveal genotype? C. How can Mendel's postulates of segregation and independent assortment be explained by meiosis? D. Explain the genotypic and phenotypic ratios predicted when performing a monohybrid and a dihybrid cross of heterozygotes? E. How can you use the product rule and sum rule to calculate the probability of a particular genotype resulting from crossing parents of specific genotypes?
Human females have two X chromosomes (XX); males have one X and one Y chromosome (XY). a. With respect to X chromosome alleles, how many different types of gametes can a male produce? b. If a female is homozygous for an allele on an X chromosome, how many types of gametes can she produce with respect to that allele? c. If a female is heterozygous for an X chromosome allele, how many types of gametes can she produce with respect to that allele?
Part 3: Use homologous chromosomes marked with alleles “A” and “a” and a second pair of homologs marked with alleles “B” and “b”. to demonstrate Mendel’s Principle of Independent Assortment in cells in Meiosis. Indicate what phase this happens in meiosis. Part 4: Use AaBb x AaBb and two Punnett squares to demonstrate Mendel’s Principle of Independent Assortment. Write the expected phenotypic ratios under each Punnett square. Now, multiply the probabilities of each event to get combined probabilities for BOTH genes. i.e. the chance of being homozygous recessive for both genes is 1/4 x 1/4 =1/16.
Determine which progeny contain single crossovers and which contain double crossovers and indicate where among the genes the crossovers occurred.
Table 8.1 shows that Turner syndrome occurs when an individual inherits one X chromosome but lacks a second sex chromosome. Can Turner syndrome be due to nondisjunction during oogenesis, spermatogenesis, or both? If a phenotypically normal couple has a color-blind child (due to a recessive X-linked allele) with Turner syndrome, did nondisjunction occur duringoogenesis or spermatogenesis in this child’s parents? Explain your answer.
SET 2: In corn, the following allelic pairs have been identified in chromosome 3: +/b > plant color booster vs. non-booster +lg → with ligule vs. without ligule +/v > green plant vs. virescent A test cross between triple recessive plants and plants heterozygous for the three pairs gave the following progeny: + v lg b + lg b v lg 305 148 58 + + lg b v + + + + 62 + v + 152 b + + 275 Total 1000 Calculate the parental and recombinant frequencies, the map distances between genes, and the coefficient of coincidence. Illustrate the gene map or sequence.
Black eye (B) is dominant over brown eye (b). A man that is a homozygous dominant black-eyed marries a woman that is a heterozygous black-eyed. The offspring resulted to 50% homozygous black and 50% heterozygous black. If one of their heterozygous children marries another heterozygous partner. Regardless of its gender, what are the genotypes of their children? a. 25% BB, 50% Bb, 25% bb b. 50% BB, 25% Bb, 25% bb c. 25% BB, 25% Bb, 50% bb d. 0% BB, 75% Bb, 25% bb In Law of Codominance, a pure line dominant trait crossed with a recessive trait will result to the appearance of both dominant and recessive trait in the offspring. What is the percentage of having a red-haired offspring if the parental genotype is both a heterozygous roan haired? Red hair is a dominant trait and white hair is a recessive trait. a. 100% b. 75% c. 50% d. 25% e. 0%