Create a Genetic Composite

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Objective

SWBAT create a genetic composite by exploring relationship between gentoype and phenotype.

Big Idea

Students use probability to determine phenotype from genotype.

NGSS

1 minutes

The objective of this lesson is for students to be able to explain the relationship between genotype and phenotype.  The variation of genotype and phenotypes among individuals is a direct result of sexual reproduction resulting in offspring with genetic variation.

NGSS Standards:

MS-LS3-2 Develop and use a model to describe why asexual reproduction results in offspring with identical genetic information and sexual reproduction results in offspring with genetic variation.  

Science and Engineering Practices:

SP2:  Developing and Using Models - Develop a model to describe phenomena

SP7:  Engaging in Argument from Evidence  

Crosscutting Concepts:

Cause and Effect:  Cause and effect relationships may be used to predict phenomena in natural or designed systems.  

Engage

20 minutes

To engage my students in this lesson I have them complete a Genetic Wheel activity - about themselves (of course - it's Middle School!). (SP2 Developing and Using Models)

In this activity students:

  • Distinguish their genetic traits with their classmates
  • Identify and interpret their own phenotypes (physical traits)


Instructions:  In this activity you will observe 7 common traits of the human population. Dominance is the most common trait in a population and in the lab is expressed with a capital letter.  Recessive traits are expressed with a lowercase letter.

  • Use the Genetic Wheel and place your finger in the MIDDLE of the circle (blank) either L_ or ll
  • Identify your hair color with the chart below, and move your finger from the middle of the circle to either L_ or ll
  • Proceed to the second trait and figure out your hair type, from your original answer you will move either to T_ or tt.
  • Continue this process for all 7 traits.
  • When finished you will have a special student number #.

Make sure to demonstrate the process and thinking of using the wheel, and also check to insure student understanding of each trait.  It is important that you project pictures of traits so students can visually see what they are looking for.  If you have taught my Heredity- An Inventory of Traits Lesson students should be familiar with most of these traits.

 

 

Teacher Note:  I have included another version of same activity (Genetic Wheel B) courtesy of the California Academy of Sciences. 

Once students have completed activity students answer Genetic Wheel Discussion Questions independently and then we discuss them as a whole group.

Explore

25 minutes

In this section of lesson students build upon what they learned in the previous section of lesson (genotype/phenotype) in a partner activity to Create a Genetic Composite. (SP2: Developing and Using Models). 

Learning Objective:

Students will be able to demonstrate the relationship between genotype and phenotype.

CCC - Cause and Effect - 

  • Cause and effect relationships may be used to predict phenomena in natural or designed systems.

  • Phenomena may have more than one cause, and some cause and effect relationships in systems can only be described using probability.

Teacher Note:  The essence of this lesson is for students to leave activity with understanding the relationship between genotype and phenotype.  As a result it's important to point out to students that flipping the coins to determine genotype is a requirement to get to the final drawing which is the composite drawing, in other words the phenotype.  Another driving point of the lesson is how this relationship can be described using probability as a result we use pennies (50/50) to determine genotype.  This concept will be revisited more thoroughly when students are introduced to Punnett Squares.

Materials

The procedure and directions are covered in detail in the included resources.

Teacher Notes:

Only "Dad" determines gender genotype therefore only designated student flips coins to determine baby gender.  Have students work in pairs to complete activity.  Both hair and eye color are a result of two genes therefore these two traits require students to flip twice to determine genotype.  The rest of  Genetic Composite Traits are only controlled by one gene therefor only one flip is necessary. Make sure students fill out Birth Certificate as they determine traits.

Students are graded on accuracy of their "Baby Face" drawing based on the phenotype/genotype determined (see Birth Certificate). (CCC - Cause and Effect)

Explain

10 minutes

In this section of lesson students read Modern Genetics, a cK-12 article that explains the relationship between genotype and phenotype.

Once students have completed the reading, they complete the following questions:

  1. What is an allele?
  2. What is the type of allele that only affects the phenotype in the homozygous condition?
  3. If two individuals have a certain phenotype, does that mean they must have the same genotype?
  4. A tall, green plant is homozygous for each trait. If is the tall allele, and is the green allele, what is the genotype and the phenotype of this plant?

If there is time you may want to show the The Phenotype and Genotype Show video on the link between genotype and phenotype. 

 

Evaluate

5 minutes

To assess students' growth toward meeting the learning objective of the lesson, students complete an Exit Slip.  They are required to cite evidence from the lesson activities to explain relationship between genotype and phenotype. (SP7: Engaging in Argument from evidence/W.7.1 - Write arguments to support claims with clear reasons and relevant evidence.)