Module 6
1. Module 6
1.40. Lesson 9
Module 6—Mendelian Genetics: The Transmission of Traits to the Next Generation
Lesson 9—Crossing Over Frequencies and Gene Mapping
Get Focused
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Sometimes you can find what you are looking for by finding something else that should be in a similar location. Early stud finders worked this way. About 20 years ago, if you wanted to find a 2 × 4 stud in your wall, you may have used a floating magnet held close to the wall. The magnet would move directly over the stud because it was attracted to the nails in the 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 knew the location of more common genes on the same chromosome, then they were able to find the “genes of interest” quickly and easily. This is like finding the nail so that you could find the stud.
In this lesson, you will learn how genes that are found 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 following focusing questions will be examined:
- 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?
Module 6: Lesson 9 Assignment
Your teacher-marked Module 6: Lesson 9 Assignment requires you to submit the following:
- a lab on mapping chromosomes
- participation in a discussion on the importance of gene mapping
Download a copy of the Module 6: Lesson 9 Assignment to your computer now. You will receive further instructions on how to complete this assignment later in the lesson.
Add terms from this lesson to your flash cards.
You must decide what to do with the questions that are not marked by the teacher.
Remember that these questions provide you with the practice and feedback that you need to successfully complete this course. You should record the answers to all of the questions and place those answers in your course folder.
You also have the option of trying additional questions from the textbook for further practice. Consult with your teacher for the answers to these questions. The Key will also provide you with many Diploma Exam-style multiple-choice, numerical-response, and written-response questions that will be an excellent review of the module. Practising your responses to these types of questions is good preparation for the Diploma Exam.