Morgan and his students observed spontaneous mutations in fruit flies, crossed the mutant flies and recorded recombination frequencies to create the first chromosomal map. Lets consider the importance of knowing gene locations on chromosomes and how we can use simple organisms to help us understand complex problems.  Read the following articles to help in your clarification between linked genes and sex-linked genes.

Genetics and Genomics Timeline (2004). 1910 (Links to an external site.).
Genetics. (nd). Sex Linkage (Links to an external site.).

Because males are hemizygotic for their traits (or heterogametic regarding their sex chromosomes).XY..they provide a relatively easier tool for observing some traits in the offspring.  Morgan used this trend to observe that certain traits are linked to a particular sex-determining chromosome.  This means traits on the X chromosome (sex linked genes) were used to advance our broader understanding of gene linkage and how crossing-over for any homologous pair can lead to recombinant phenotypes in the progeny.

Lets discuss the following:

1. What does it mean for genes to be linked?

2. What does it mean for genes to be sex-linked?

3. Why is it important to know gene location on chromosomes?

4.  Identify and describe an X-linked disorder (put the name of the disorder in the first line of your post)

5. Explain how this trait was discovered, Discuss preventions/treatments for this trait due to its location on the X chromosome.

References
http://www.genomenewsnetwork.org/resources/timeline/1910_Morgan.php

https://learn.genetics.utah.edu/content/pigeons/sexlinkage/

https://www.ncbi.nlm.nih.gov/guide/
https://www.ncbi.nlm.nih.gov/omim/