Genetics III: Inheritance of Traits
I.
Benchmark/ Standard: B4.1 Genetics and Inherited Traits
a. Hereditary information is contained in genes, located in the chromosomes of
each cell. Cells contain many thousands of different genes. One or many
genes can determine an inherited trait of an individual, and a single gene can
influence more than one trait. Before a cell divides, this genetic information
must be copied and apportioned evenly into the daughter cells.
i. B4.1B Explain that the information passed from parents to offspring
is transmitted by means of genes that are coded in DNA molecules.
These genes contain the information for the production of proteins.
ii. B4.1c Differentiate between dominant, recessive, codominant,
polygenic, and sex-linked traits.
iii. B4.1d Explain the genetic basis for Mendel’s laws of segregation and
independent assortment.
I.
Behavioral/ Objective: After completing the generations of traits activity,
students will show they understand that characteristics are passed down from
parent to child by means of genes by completing the worksheet and
comprehension questions.
II.
Anticipatory Set: Take out your observable traits survey from yesterday. The
categories are listed on the board. Go up to the board. Place a tally-mark in the
column if you were positive for the trait. After students have placed the data on
the board, review as class that some traits are more common than others.
III.
Objective/ Purpose: “Yesterday we took an inventory of our inherited traits like
rolling our tongue, handedness, and dimples. Each one of us is a unique
combination of traits. This unique combination is due to the law of segregation
and the law of independent assortment. We are going to watch a short YouTube
video and talk about those laws. Then we are going to do a simulation with
gingerbread men to model how traits are passed down through the generations.
IV.
Input:
a. Task Analysis:
i. Students will watch the YouTube video: Gregor Mendel: Great Minds.
http://www.youtube.com/watch?v=GTiOETaZg4w (11 minutes)
1. Law of segregation: pause video and write the law on the
board, replay this section (5:00 minutes)
a. The Law of Segregation states that every individual
possesses a pair of alleles (assuming diploidy) for any
particular trait and that each parent passes a
randomly selected copy (allele) of only one of these
to its offspring. The offspring then receives its own
pair of alleles for that trait. Whichever of the two
alleles in the offspring is dominant determines how
the offspring expresses that trait (e.g. the color and
height of a plant, or the color of an animal's fur).
2. Law of independent assortment: pause video and write the
law of the board, replay this section (6:00 minutes)
a. Separate genes for separate traits are passed
independently of one another from parents to
offspring.
b. Mendel concluded that different traits are inherited
independently of each other, so that there is no
relation, for example, between a cat's color and tail
length. This is actually only true for genes that are
not linked to each other.
ii. Key Concepts (Mendel’s laws): Students should get a sheet of paper
and draw a line down the middle. On one side they should write Law
of segregation, on the other side they should write law of
independent assortment.
1. Give the definition of each law in your own words.
2. Draw a symbol/picture to represent it.
3. Give an example.
iii. Gingerbread man lab.
1. Introduction: Explain that the law of segregation and
independent assortment are part of the inheritance of traits.
Both contribute to the reason why all of us are unique
individuals and why we may resemble our parents.
2. Each student should receive instructions, worksheet, and
questions.
a. http://teach.genetics.utah.edu/content/heredity/ht
ml/generations.html
3. Students will work in pairs to complete the activity.
4. Prepare the following in advance for each group:
a. 6 cups
b. 6 brown pom poms
c. 6 red pom poms
d. 6 green pom poms
e. 6 yellow pom poms
5. Students will follow the instruction sheet to complete the
activity. Using pom-poms they will simulate genetic crosses
that model the passing of traits through generations.
6. Complete the questions worksheet for the next class.
b. Thinking Levels:
i. Knowledge: recall genetic terminology: allele, trait, phenotype,
genotype, etc.
ii. Comprehension: Explain inheritance of traits, law of segregation, law
of independent assortment.
iii. Application: demonstrate inheritance of traits by completing the
gingerbread men activity.
iv. Analyze: Analyze and draw conclusion about the activity by
answering the comprehension questions.
c. Learning Styles:
i. Visual: YouTube video, key concepts, board work, worksheet to
record data during activity.
ii. Auditory: YouTube video.
iii. Kinesthetic: Gingerbread men activity.
iv. Interpersonal: students will work in groups to complete the
gingerbread men activity.
d. Methods and Materials:
i. Ways of presenting: board work, class discussion, YouTube video,
short lecture to introduce the activity.
ii. Materials needed: cups, pom-poms, instructions, worksheet, and
questions handouts, paper for key concepts, YouTube video,
projector, and whiteboard.
V.
Modeling:
a. Model how students should set up their key concepts sheet.
b. Model the steps of the gingerbread man activity.
VI.
Check for understanding:
a. Key Concepts to explain the law of segregation and law of independent
assortment.
b. Comprehension questions to accompany the worksheet.
VII.
Guided Practice: The teacher will circulate to answer questions during the
activities.
VIII.
Independent Practice:
a. Key Concept comprehension check.
b. Students will complete the comprehension questions for the next class.
IX.
Closure: Each group should complete an exit card to answer the following
questions
a. What are traits that you have inherited from your parents?
b. Do your siblings have all the same traits as you? Why or why not?