Question

please explain the background to understanding the problem and how solve it. thank you!

due Thursday, 10/24/19 Extra brain-teaser: rangutans are an endangered species in their natural environment (Sumatra and Borneo). so a captive breeding program has been established. One program component is research into the cytogenetics (chromosome structure of orangutans. All orangutans from Borneo have one form of chromosome as shown below, and all Sumatra orangutans carry a different form. Before this difference was noticed, some matings were carried out between animals from different islands, and 12 hybrid progeny are now held in captivity. 1.1 1. pllp! 2 Acrocentric 23 21 Borneo u 22 21 21.1 1.1 412 pl2 Sumatra Metaceninc a. What is the proper term to characterize the difference between these two chromosomes? The Borneo halon Acrocentric chromosome and the sumatra has a Metacentre chromosome b. Make a drawing of how these chromosomes would pair at meiosis in one of the hybrid individuals. c. In 45% of meioses, there will be a crossover somewhere between bands p1.1 and 21.2. Draw the gamete chromosomes that would result from a meiosis where a single crossover occurred in band 21.2. d. Given that the recombination rate between p1.1 and 1.2 is 45%, what proportion of gametes produced by one of the hybrid orangutans will give rise to viable progeny? Explain briefly.

Answer 1

ANSWER : (a) The two chromosomes differ in the position . of theire centromeres . Since the Orangutans from Berne have chremesome whose centremere lies a little towards the end, they are checaderised as acrecentric. > Also, since the Orangutans from Sumatre have i chromosone whose centremere lies a little away from centree, it is characterised as sub-metacenbid (b). Both the chromosomes have the same of genes, but arranged differently. be seen that, they exhibit pericentilic Hence, their paining during meiasis can represented as follows. I set It can inversion. be Sumatica Berence 9,1-1 W 93.1 922 92-1 q1-2 pl.2. AAAA &

(c) The gametes occuring in produced due band q 1.2 to a are crossovere as follow Pl.1 recombination 91.2 site 93.1 92-2 92.1 q3.1 922 92.1 pll alt 91.2 pl.2. D . 93.1 922 92.1 plit 911 912 92.1 92.2 98.1 p1-2 1- all 91.2 92.1 92.2 q3.1 Gametes (i) and (iv) are parental type, and have all the genes present in them Gametes (i) and (ii) are recombinant lypes, and have duplication and deletion of one or more genes. Chreemesme Duplication Deletion. (ii) 03.1, 922,921 pl.2 (iii) | pl. 2 I q.8.1, 92.2, 92.1

(od). A recombination frequency of 45% means that, out of 100 gametes, 45 would reecombinant type, which tend to be enviable, in case of pericentric enveresion. Since they have deeplication and deletion of ne or more genes, they tend to be enviable , and don't produce viable offsprings Hence, rest of the 55% (= 100-45) gameter would give rise to viable preogeny , if the gameles were produced by a hybrid Orangutan.