Orangutans are an endangered species in their natural environment (the islands of Borneo and Sumatra), and so a captive-breeding program has been established using orangutans currently held in zoos throughout the world. One component of this program is research into orangutan cytogenetics. This research has shown that all orangutans from Borneo carry one form of chromosome 2, as shown in the accompanying diagram, and all orangutans from Sumatra carry the other form. Before this cytogenetic difference became known, some matings were carried out between animals from different islands, and 14 hybrid progeny are now being raised in captivitya. What term or terms describe the differences between these chromosomes? b. Draw the chromosomes 2, paired in the first meiotic prophase, of such a hybrid orangutan. Be sure to show all the landmarks indicated in the accompanying diagram, and label all parts of your drawing. c. In 30 percent of meioses, there will be a crossover somewhere in the region between bands p1.1 and q1.2. Draw the gamete chromosomes 2 that would result from a meiosis in which a single crossover occurred within band q1.1.d. What fraction of the gametes produced by a hybrid orangutan will give rise to viable progeny, if these chromosomes are the only ones that differ between the parents? (Problem 48 is from Rosemary Redfield.)
Orangutans are an endangered species in their natural
environment (the islands of Borneo and Sumatra), and
so a captive-breeding program has been established using orangutans currently held in zoos throughout the
world. One component of this program is research into
orangutan cytogenetics. This research has shown that all
orangutans from Borneo carry one form of chromosome
2, as shown in the accompanying diagram, and all orangutans from Sumatra carry the other form. Before this
cytogenetic difference became known, some matings
were carried out between animals from different islands,
and 14 hybrid progeny are now being raised in captivitya. What term or terms describe the differences between these chromosomes?
b. Draw the chromosomes 2, paired in the first meiotic
prophase, of such a hybrid orangutan. Be sure to show all
the landmarks indicated in the accompanying diagram,
and label all parts of your drawing.
c. In 30 percent of meioses, there will be a crossover
somewhere in the region between bands p1.1 and q1.2.
Draw the gamete chromosomes 2 that would result from
a meiosis in which a single crossover occurred within
band q1.1.d. What fraction of the gametes produced by a hybrid
orangutan will give rise to viable progeny, if these
chromosomes are the only ones that differ between the
parents? (Problem 48 is from Rosemary Redfield.)
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