Download Sample “Content” Lesson Plan: 45 minutes total

Content Lesson Plan #2: 45 minutes
Genes and Traits: Dominant versus Recessive
Aim:
How do genes determine my visible and invisible traits?
Objectives:
SWBAT compare phenotype and genotype.
SWBAT apply the standard format to describe an organisms genotype (i.e. Aa)
SWBAT apply their knowledge of dominant and recessive to determine what phenotype an
organism will have.
SWBAT answer state assessment questions 2006- #37, 2005- #34
Set Up – 5 min
Students come in and
 Get their notebook
 Copy these questions (summary frame) into their notebooks
Q: How many copies of each gene does each cell have?
Q: How is it determined which copy of the gene is displayed as a physical trait?
Q: What are the genotype and phenotype and how do we represent them?
Q: How many genes are needed to determine one trait?
Purpose Overview – 2 min
I add this topic to the “big idea” concept map on the wall, and explain how it relates to previous
topics.
Mini-lesson: “Genes and Traits: Dominant and Recessive” – 15 min
I verbally explain the answers to the questions in the summary frame as the students take notes. I
will draw the following diagrams to aid in understanding: cell with chromosomes in the nucleus
with 2 copies of a gene marked
I will define key vocabulary words on the board under the appropriate question, and ask different
students to put them on the science vocabulary word wall: allele, dominant, recessive, genotype,
phenotype
Q: How many copies of each gene does each cell have?
 Two copies of each gene, called alleles (drawing)
 Allele- 1 version of the gene
 On separate chromosomes
Q: How is it determined which copy of the gene is displayed as a physical trait?
 Dominant allele versus recessive allele
 The dominant allele is displayed, while the recessive allele is hidden.
 If there are two recessive alleles, the recessive allele is displayed
 Example: eye color
o Dominant allele is brown eyes, recessive allele is green eyes
o If I have 2 brown eye alleles, I will have brown eyes.
o If I have 2 blue eye alleles, I will have green eyes
o What if I have 1 of each?
Q: What are the genotype and phenotype and how do we represent them?
 Genotype used to represent which alleles an organism has.
 Usually the letter is determined by the dominant allele. Capital letter for dominant allele,
lower case for recessive allele
 So, for the example above, B for brown eyes, b for green eyes.
 2 brown eye alleles= BB, 2 green eye alleles= bb, 1 of each = Bb
 Phenotype: expressed/displayed traits (i.e. I actually have brown or green eyes)
Q: How many genes are needed to determine one trait?
 Any number of genes to determine one trait.
 For example, being able to roll your tongue is determined by just one pair of genes, while
height may be determined by several.
Practice with Genotypes – 5 min (individually)
Students practice writing genotypes based on scenarios I put up on chart paper:
1. The allele for rolling your tongue is dominant over the allele for non-rolling.
How can we represent the allele for rolling?:
For non-rolling?:
2. What is the genotype of a person with one of each allele?:
Can they roll their tongue?:
4. What is the genotype of a person who cannot roll their tongue?
3 different students are selected to put their answers on the chart paper.
Dominant/Recessive Activity- Mr. Potatohead (in groups)- 12 min
Students work in groups of 4 with construction paper potatoheads, features, and fun tack. Students
have 5 different scenarios and must build the proper potatohead. I will circulate to make sure they
are on track (class work points are given to groups on task). We will share out at the end.
1. A blue nose is dominant, a yellow nose is recessive. Your potatohead has a genotype of BB.
2. Big lips are recessive, small lips are dominant. Your potatohead has a genotype of ss.
3. Ears are dominant, no ears is recessive. Your potatohead has a genotype of Ee.
4. Long hair is dominant, short hair is recessive. Your potatohead has one dominant allele
and one recessive allele. Write the genotype and describe the phenotype, then add the
appropriate hair to your potatohead.
5. (Note: This will be challenging for the students) Eye color is determined by “Incomplete
Dominance”. The dominant allele is for blue eyes, the recessive allele is for yellow eyes.
a. Your potatohead has one of each allele. What is the genotype of your potatohead?
b. If “incomplete dominance” means that the phenotype is a combination of the two
alleles, what color eyes will he have? Attach the correct color eyes to your
potatohead.
Closure - 5 min
Students answer the two state assessment questions individually: 2006- #37, 2005- #34
Students write answers in their notebooks while I circulate to see how many get them right. Correct
answers are reviewed as a class.
Clean Up – 1min
With exactly one minute before the bell I direct students to return all supplies and pack up.