Unit 4, Chapter 12, Section 1: Mendel’s Law of Heredity

Biology-The Dynamics of Life, Glencoe, pp285-297

Anticipatory Set:

	In this unit we will explore genetics. Genetics is the branch of biology that studies heredity, or the passing on of characteristics from parents to offspring.
	Explain K-W-L process and start lesson by listing on the overhead all of the things we know or think we know and what we want to know about genetics.
	As the unit progresses, we will refer back to what we have listed and at the end of the unit we will list what we have actually learned.
	Make copies of list for students so they can refer to it as we progress.

Objectives and Purpose:

After today’s lesson, the student will be able to:

· Gain a sense of understanding as to the scope of genetics

· Summarize Mendel’s experiments

· Explain the laws of segregation and independent assortment

· Compare/contrast phenotype and genotype

· Explain the steps of a monohybrid and dihybrid cross

· Construct Punnett squares

The purpose of this lesson is to begin to understand the importance of genetics in determining how every organism is created. Genetics enables us to understand how traits are passed down from parents to offspring.

Instructional Input:

The teacher will provide the following input.

· Introduce the terms heredity, genetics, and traits

· Summarize the importance of genetics and its relevance to their learning

· Give biography of Mendel and his work

· Explain why he used pea plants

· Go through steps of monohybrid cross using overhead to illustrate

· Introduce terms alleles, dominant and recessive genes, law of segregation, phenotype and genotype, homozygous and heterozygous

· Explain dihybrid cross using overhead

· Introduce law of independent assortment

Modeling:

The teacher will demonstrate how Punnett squares are used to diagram genetic crosses by creating one step-by-step on the overhead.

Checking for Understanding:

The teacher will construct a Punnett square on the overhead with students talking through the steps and guiding the process.

Guided Practice:

Students will get in pairs and do question # 3 of the section review on pg. 297.

#3-One parent is homozygous for a certain trait and the other parent is heterozygous. Make a Punnett square to determine what fraction of their offspring is expected to be heterozygous.

A volunteer pair will then be asked to go through the process on the board.

Independent Practice:

Students will read chapter 12, answer the following questions from p.297 and define the following terms from p. 286. We will then go over them in the next class.

1. Why did the flower structure of pea plants make them suitable for Mendel’s genetic studies?

2. What is the genotype of a homozygous and a heterozygous tall pea plant?

3. In garden peas, the allele for yellow peas is dominant to the allele for green peas. Suppose you have a plant with yellow peas but you don’t know whether it is homozygous dominant or heterozygous. What experiment could you do to find out? Draw a Punnett square to help you.

Terms:

Heredity Law of segregation

Genetics Phenotype

Trait Genotype

Gamete Homozygous

Fertilization Heterozygous

Pollination Dihybrid cross

Allele Law of independent assortment

Dominant Recessive

Closing:

We have begun our exploration of genetics and can begin to see how it accounts for the passing on of traits from parents to offspring. Next we will examine the process of meiosis and see exactly how this genetic material is passed on within the cell.