Create a summary table of the information on a whiteboard or a large sheet of paper. Graves mentions X chromosome inactivation, first proposed by Mary Lyon. Find out more about this hypothesis and how X-chromosome inactivation in marsupials is different. Write a paragraph on your findings. Read this article and summarise it.
Students locate fictitious genes on a chromosome, using crossover frequencies.
They then read an essay on sex chromosomes, and answer the questions that follow.