Lesson Plan:

Lesson Title: Martian-Mallow Mobots

Class Time Required: 45 minutes

Overview and Purpose:

As an introduction to this lesson students are told that space probes have discovered tiny creatures on the surface of Mars. These tiny creatures are called Martian-Mallow Mobots. Chromosomal analysis indicates that they have 9 pairs of chromosomes for a total of 18 chromosomes. During this lesson, students will learn about genetic variation as groups construct Martian-Mallow Mobot offspring.

General Goals:

Students will understand that sexual reproduction produces variation of offspring

Specific Objectives:

* Students will demonstrate the separation and random donation of maternal and paternal genes during sexual reproduction.
* Students will identify the relationship of genotypes in determining phenotypes.
* Students will identify and differentiate dominant, recessive, and codominant genes.
* Students will recognize variation in offspring.
California Content Standards (http:/ www.cde.ca.gov\board\board\html):
2b. Students know that sexual reproduction produces offspring that inherit half their
genes from each parent. During fertilization, the egg and sperm cells combine their
single sets of chromosomes to form a zygote containing two sets, or the diploid
number of chromosomes for a species.
2d. Students know plant and animal cells contain many thousands of different genes and
typically have two copies of every gene. The two copies (alleles) of the gene may or
may not be identical, and one may be dominant in determining the phenotype while
the other is recessive.

Materials Needed (per group):

4 large marshmallows 2 small nails
3 small marshmallows 3 thumbtacks
1 colored marshmallow 2 envelopes
4 colored pushpins 3 inch piece of pipe cleaner
parent chromosome template
mobot phenotype decoder key
3 toothpicks data sheet (for each student)Activities (step by step procedure)

Activities (Step by Step Procedure)

1. Prior to instruction make copies of mother and father chromosomes. For identification purposes, copy mother’s chromosomes onto pink paper and father’s genes onto blue paper. Cut out chromosomes and place into appropriate envelopes, one labeled “mother” and the other labeled “father”. Set up a materials station in the back of the classroom with the supplies listed under materials. Material labels may be downloaded and printed.
2. Review concepts such as dominant, recessive, and codominant genes.
3. Arrange students in groups of three or four. Each student group will be given envelopes containing the genes of a mother and father Mobot. The gene pairs from each parent will control the following traits: presence of antenna, color of legs, strait or curly tail, number of body segments, number of humps, number of eyes, and color of nose.
4. Instruct students take chromosomes out of each envelope and to place them face down on the table. Students should then sort the chromosomes by size of both mother and father mobots.
5. Without turning the chromosomes over, instruct students to select one pink chromosome and one blue chromosome of the longest size. This pair of chromosomes should be placed in the center of the table to represent the baby mobot’s chromosomes. This procedure will be repeated for all other size chromosomes.
6. Instruct students to turn over chromosome pairs and record the baby mobot’s genotype on a data table.
7. Instruct students to analyze the resulting genotype in order to determine the baby mobot’s phenotype (what it looks like).
8. Assign a materials manager from each group to gather supplies needed to construct the new baby mobot. Large marshmallows will be used for the head and body parts. Small marshmallows represent body humps, and colored marshmallows will be added for a nose. Small nails will represent antenna and thumbtacks will be used for eyes. Pipe cleaners may be bent for tails and push pins will be used for legs.
9. Instruct groups to assemble and name their baby mobot.
10. Assign a reporter to present baby mobot to the class.
11. As presentations are made, students should compare other group’s mobots to theirs. Students should record the number of similar and dissimilar genes.
12. Conclude the lesson by asking students to complete assessment questions.

Teaching Strategies:

1. Review dominant, recessive, and codominant, homozygous and heterozygous genes prior to lesson.
2. Form teams of three to four students. Assign a materials manager, facilitator, recorder, and reporter for each team.
3. After each group has constructed and presented baby mobot to class, display offspring produced by each group so that students can compare similarities and differences.
4. Use assessment questions as a check for comprehension.