Module 6 Lesson 8 - 1

Get Focused

Sometimes, you can find what you are looking for by finding something else that should be in a similar location. Early wall stud finders worked this way. About 20 years ago, if someone wanted to find a 2 × 4 stud in a wall, he or she may have used a floating magnet held close to the wall. The idea was the magnet would be attracted to the nails in the stud and move towards the nails when the device was directly over a stud.

After discovering that genes occurred on chromosomes, scientists learned how to map the relative distances between these genes. This can be tremendously helpful for locating genes of interest, such as genes that cause disease. When scientists already know where to find a  common gene on the same chromosome, these "genes of interest" can be located more quickly and easily.

In this lesson, you will learn how genes on the same chromosome tend to move together and are said to be linked. Using your understanding of crossing over from meiosis, you will learn how this allows scientists to map the relative locations of genes on the same chromosome.

In this lesson, the focusing questions are the following:

• How does crossing over in chromosomes relate to finding the locations of genes on chromosomes?

• What is the importance of knowing where genes are located on a chromosome?