Lesson+4

Grade Level:  10

Unit:  Biology

Lesson Objectives (include 4 or 5): Student will understand  Student will be able to  Time Required to complete this lesson:  1 to 2 weeks
 * That our physical traits are determined by genes that we inherit from our relatives.
 * The principles of genetic inheritance as theorized by Gregor Mendel.
 * The definition of dominant and recessive **alleles** (gene variations for a particular trait).
 * Why traits that occur on the X sex chromosome are significantly more common in males.
 * Trace the progress of alleles through their family tree.

Title of lesson:  Genetic pedigree

Description of lesson (if you were to describe to a parent what was happening in the classroom for this lesson, what would you say in 3-5 sentences).  Students will gain an understanding of how genetic inheritance works by examining the blood types of family members. I've chosen the trait of blood type because it is a common feature of all people and it is controlled by a single gene. There are 3 alleles for blood type (A, B, and i). A and B are dominant alleles and i is recessive. A and B will mask the expression of the i allele, but A and B are **codominant**. If A and B occur together, neither will dominate the other; they will both be expressed as an AB blood type. The A blood type is expressed with an AA or Ai genotype and B blood type by BB or Bi. The O blood type is expressed with an ii genotype. Knowing that they inherit one blood type allele from their father and one from their mother, a student can determine the sources of alleles and the genotypes for those sources provided everyone's blood type is known. I had also wanted to do the same exercise for the red-green colorblindness trait, a relatively common X linked trait. Statistically, the average high school should have 3 or 4 boys that are colorblind, but this is still not common enough to base a lesson upon. If a colorblind student is present in the classroom and is willing to base the assignment on the colorblindness trait, he may do so.

Assignment (homework or in-class: this is how the learner will practice the learning that has just occurred):  Students will create a pedigree that includes all of the members of their family that they can determine the blood types of (parents, siblings, grandparents, uncles, aunts, and cousins). Remembering the above rules of how blood types are determined, students can deduce the genotype of each family member. Students can create a rough draft of their pedigree with pencil and paper, but the final draft should be a word processed document with graphics or a Power Point slide.

Resources/materials needed:  Data on the blood types of family members (word of mouth is OK), word processing or Power Point software to create the final draft. Video on Mendel's principles of genetic inheritance on my Top 11 Science Videos playlist accessible from the link on the Science Theater page.

Technology used:  Word processing or Power Point software

The technology used in this lesson changes the teaching / learning in this way: Allows students to create a well polished assignment. Video can be accessed from any computer.