a) Considering random segregation of the chromosome, determine the genotype and proportion of the sperm produced by the trisomic male fruit fly with genotype ++ey . b) Determine the expected ratio of the eyeless to normal eyed flies produced by the union of the sperm with the egg having genotype eyey producing an eyeless phenotype . Introduction: The segregation of the chromosome during cell division is an important phenomenon. If the chromosome fails to segregate properly, it is called non-disjunction, and it could have resulted in the daughter cell with one extra chromosome ( n+1 ) and the other with a missing chromosome ( n-1 ) condition. The cell with improper distribution of the chromosomes may reduce their survival rate as compared to the normal cell. In the germ cells, non-disjunction results in the formation of gametes with extra or missing chromosomes which leads to the production of aneuploidy gametes. Germ cells, egg or sperms, are haploid cells, containing a single pair of chromosome. The condition of the presence of extra chromosome ( 2n+1 ) in the zygote due to the union of aneuploid gamete with a normal haploid gamete is known as trisomy.

Question

Want to see the full answer?

Answer 1

Question

Chapter 13, Problem 17P

Summary Introduction

To analyze:

a) Considering random segregation of the chromosome, determine the genotype and proportion of the sperm produced by the trisomic male fruit fly with genotype ++ey.

b) Determine the expected ratio of the eyeless to normal eyed flies produced by the union of the sperm with the egg having genotype eyey producing an eyeless phenotype.

Introduction:

The segregation of the chromosome during cell division is an important phenomenon. If the chromosome fails to segregate properly, it is called non-disjunction, and it could have resulted in the daughter cell with one extra chromosome (n+1) and the other with a missing chromosome (n-1) condition.

The cell with improper distribution of the chromosomes may reduce their survival rate as compared to the normal cell. In the germ cells, non-disjunction results in the formation of gametes with extra or missing chromosomes which leads to the production of aneuploidy gametes. Germ cells, egg or sperms, are haploid cells, containing a single pair of chromosome. The condition of the presence of extra chromosome (2n+1) in the zygote due to the union of aneuploid gamete with a normal haploid gamete is known as trisomy.

Expert Solution & Answer

Want to see the full answer?

Check out a sample textbook solution

See solution

Students have asked these similar questions

The Drosophila chromosome 4 is extremely small;virtually no recombination occurs between genes onthis chromosome. You have available three differentlymarked chromosome 4s: one has a recessive allele ofthe gene eyeless (ey), causing very small eyes; one hasa recessive allele of the cubitus interruptus (ci) gene,which causes disruptions in the veins on the wings;and the third carries recessive alleles of both genes.Drosophila adults can survive with two or three, butnot with one or four, copies of chromosome 4.a. How could you use these three chromosomes tofind Drosophila mutants with defective meiosescausing an elevated rate of nondisjunction?b. Would your technique allow you to discriminatenondisjunction occurring during the first meioticdivision from nondisjunction occurring during thesecond meiotic division?c. What progeny types would you expect if a flyrecognizably formed from a gamete produced bynondisjunction were testcrossed to a fly homozygous for a chromosome 4 carrying both ey…

The gene for the production of eye colour in this species of fruit fly can be expressed aseither normal red-eyes or as brown-eyes. The allele for the normal red eyes is dominant tothat of brown, and is transmitted in normal Mendelian fashion.A gene involved with body colour in this species of fruit fly is located on the non-homologousportion of the X chromosome, and has two alleles, grey and yellow, where the grey allele isdominant to yellow.The two genes are NOT linked.a) Produce a key to clearly show the nature of the alleles associated with the eye colour inthis species of Drosophila, and in each case justify your choice of letters and / or style ofpresentation to best depict the genetics involved.

The maternal-effect mutation bicoid (bcd) is recessive. Inthe absence of the bicoid protein product, embryogenesis isnot completed. Consider a cross between a female heterozygousfor the bicoid mutation (bcd+/ bcd-) and a homozygousmale(bcd-/ bcd-). Predict the outcome (normal vs. failed embryogenesis) inthe F1 and F2 generations of the cross described.