Sister chromatids are 100% identical to each other unless they have undergone a recombination event with the homologous chromosome.

Put the following events concerning homologous recombination (the mechanism by which crossing over occurs) in order. 1 2 3 ين 4 Strand invasion and formation of the D-loop Resolution of holiday junctions Initiation of a double stranded break of one non-sister chromatid. Remove nucleotides from ends of DNA strands at the site of the double stranded DNA break.

What are sister chromatids? What is the process that forms two sister chromatids from a single chromosome? Explain how this process works.

A somatic cell has the genotype DdEe. All chromosomes in this organism are metacentric. Show metaphase and the results of mitosis if the D and E locus are linked on the same chromosome in trans configuration. A sexually reproducing organism has the following phenotype DdEeAaTt: The D and E loci are on the same arm of a metacentric chromosome in cis configuration. The A locus is on the long arm of an acrocentric chromosome and the T locus is on a telocentric chromosome. 2.1. What is the haploid number of this organism? 2.2. Using diagrams show a ceii at metaphase of mitosis and show the results of mitosis.

Chromosome structure is composed of the following Telomere Centromere Chromatids O All of the above

Variations in Chromosome NumberAneuploidy Describe the process of nondisjunction and explain when it takes place during cell division.

A cell from a human female has just undergone mitosis. For unknown reasons, the centromere of chromosome 7 failed to divide. Describe the chromosomal contents of the daughter cells.

Please fill out the following table for a bat species with (2n = 42)

The image below shows a somatic cell from an organism for which 2n = 4 (the cell from the image below). Which of the cells beneath it (cells A, B, C or D) could be a gamete from this organism? Explain why you chose the cell you did discussing the changes in chromosome number nd DNA content of a cell throughout the cell cycle. You should also explain if any of the other images could represent a cell from this organism in stages of meiosis or mitosis or other stages of the cell cycle. X Xx C "₁ XX B XX X X

An Hfrstrain that is a *b*c*d* e*f* g *h* is mated with an F strain that is a b e d e f gh. The mating is interrupted at 5 minutes interval, and the genotypes of the F recombinants are determined. The results obtained are tabulated in Table 2. Draw the map of the Hfrchromosome and indicate the position of the origin of transfer, the direction of the transfer and the minutes between genes. Table 2:Entry time of Hfr chromosome into recipient cell. Time a d e f h 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +