Miss Wilcox

Biology I

Genetics – June 21, 2007

Approximate time: 50 minutes

Objectives: TSW

1.Define key genetic terms (gene, alleles, genotype, phenotype, homozygous, heterozygous). 5d

2.Discuss the significant contributions of scientist, Gregor Mendel. 5d

3.Derive the Law of Dominance from a summary of Mendel's data. 5d, 5e

4.Predict possible genotypes and phenotypes of offspring. 5e

Materials:

Whiteboard, markers, textbook, overhead, transparencies, vis-a-vis pens

Warm-up:

In your notebook, define the following terms: gene, allele, genotype, homozygous, heterozygous, phenyotype.

Set: (review, objectives, involve, relevance)

Say, “I'm going to tell you a little story about a man and his pea plants. This man's name was Gregor Mendel, and he lived in a monastery studying peas. By studying pea plants, Mendel was able to come up with conclusions about heredity long before people knew about DNA and chromosomes. Yesterday, we wrapped up the section on molecular genetics and technology, and today, we begin Mendelian genetics, the branch of genetics having to do with heredity. What does heredity mean? Can anyone tell me what color eyes a child would have if his mom had blue eyes and his dad had brown? By the end of today, we will have learned more about the Mendel's contributions to genetics and some of his conclusions about heredity. We will also have begun to predict the the traits of offspring from a pairing of two organisms.”

Procedures:

1.Discuss key genetic terms.

2.Tell the “story” of Mendel and initiate the roleplay of Gregor Mendel's lab: students are all scientists in Mendel's lab and are given a summary of the data he used to derive the Law of Dominance. Guide students to come up with the law on their own. Ask, what do you predict? What has happened? How could we make a rule for this? (The aim is to have them decide that one of the colors must have greater influence – it must be dominant over the other.)

3.Show guinea pig example illustrating genotype, definition, phenotype chart.

4.Overhead worksheet to check comprehension.

5.Return to “Mendel lab”. Continue with next generation. Can we make predictions?

Closure: (restate, review, involve, preview)

Say, “Today we defined some key genetic terms we'll need to know. What are they? (gene, allele, genotype, phenotype, homozygous, heterozygous). What do they mean? We began to discuss Mendel and his contributions to genetics, such as the Law of Dominance which we were able to derive on our own with his data. We also began using our knowledge of dominance and recessiveness to predict phenotypes and genotypes. Tomorrow, we will continue with predictions, practicing how to use a way of organizing pairings to better predict offspring called Punnett square, which is a common tool in Mendelian genetics. Homework tonight? Study for quiz tomorrow.”

Assessment:

    Informal: TTW observe students and listen to their discussion on deriving the law     of dominance.

    Formal: TTW grade the in-class practice and the quiz on key terms and genotypes     next lesson.     The grades will be recorded in the gradebook.

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