1. Mitosis and Asexual Reproduction
Activity 3
Mitosis and Asexual Reproduction

3. Read the Introduction
Asexual reproduction takes only one parent to produce offspring.
Mitosis occurs when a single cell divides to produce two identical daughter cells.
Discuss with students which types of organisms reproduce sexually (e.g., corn) and which types reproduce asexually (e.g., E. coli). Be sure students understand that in this activity they will study asexual reproduction.

4. Challenge
If a genetically modified cell undergoes mitosis, how likely is it that the daughter cells will contain the inserted gene?

5. As you watch the simulation, in each phase of mitosis note the chromosomes’:
shape
position within the cell
movement within the cell
Explain to students how you would like for them to work with the online simulation, which can be found on the Science and Global Issues page of the SEPUP website (sepuplhs.org/sgi).
If your state and local standards require that students be familiar with additional new vocabulary, such as centrioles and cytokinesis, this is an appropriate time to introduce and review those terms.

6. Modeling one pair of duplicated chromosomes
Emphasize that chromosomes look like this (Xs) only after the DNA has replicated during interphase and chromosomes have condensed. Procedure Step 4 is an appropriate time to review the vocabulary terms centromere and chromatid. You might challenge the students to repeat Step 4 without the assistance of Student Sheet 3.1, “Mitosis.”

7. What is the probability that a daughter cell will receive an inserted gene from a genetically modified parent cell that undergoes mitosis?
In your discussion include:
chromosomes
parent cell
daughter cell
gene
Students’ responses to Step 7 may be scored with the Understanding Concepts (UC) Scoring Guide. For more information and a sample response see your Teacher’s Edition for this activity and Teacher Resources IV: Assessment.

8. Analysis 3
A friend of yours claims that every genetically modified single-celled organism that reproduces asexually would pass along the inserted gene to its daughter cells. Based on your work in this activity, is that claim valid? Explain.
In this scenario, if the insertion is made into the bacterial chromosome, or in eukaryotic organisms where the genetic modification occurs in the chromosomes, all inserted genes will be passed on to the daughter cells. Note for students that if the gene were inserted into the plasmid, for example in a bacterial genetic modification, the plasmid DNA is usually (but not always) passed on to all offspring.

9. Revisit the Challenge
If a genetically modified cell undergoes mitosis, how likely is it that the daughter cells will contain the inserted gene?
Refer back to Analysis Question 4, which addresses one concern often raised about growing genetically modified organisms. Ask students to share their ideas with the class. They should incorporate evidence from their work in this activity to support their ideas about the potential benefits and risks associated with the genetic modification of an organism that reproduces asexually.

10. asexual reproduction centrioles centromere chromatid chromosomes
Key Vocabulary
asexual reproduction
centrioles
centromere
chromatid
chromosomes
cytokinesis
daughter cell
mitosis
parent cell
See Teacher Resources III: Literacy for more information on key vocabulary and the most effective strategies to enhance student vocabulary learning.
Note that bold words are formally defined in this activity. Words in regular font are used in the activity, but not formally defined. The definition of a key vocabulary word should not be discussed as a class prior to the formal definition being introduced.