Why Two Heads?

Topic

Resource Type

Level

High School — General High School — AP/IB

Saved By

23 Users

Description

This activity explores images of planarians regenerating missing body parts, which serve as phenomena for learning about cell division and differentiation.

Planarians are simple multicellular animals known as flatworms. They can regenerate parts of their bodies using adult stem cells called neoblasts. When part of a planarian is cut off, its neoblasts multiply to make more stem cells. Some of these stem cells then differentiate into the cells needed to regrow the missing body parts. These images show how planarians cut in different ways regenerate over time. One of the planarians has been treated with RNA interference (RNAi) to shut off a gene involved in establishing body polarity.

The “Educator Materials” document includes background information and implementation suggestions for using the images as phenomena. The “Student Handout” includes the images and background information.

Student Learning Targets

Examine images of phenomena, make observations, and ask questions.
Collaborate with peers on ideas, ask questions that require higher levels of reasoning, and develop deeper understanding of concepts.
Describe how planarian regeneration works on a cellular level.

Estimated Time

Within one 50-minute class period.

Key Terms

amputation, mitosis, model organism, neoblast, planarian, polarity, regeneration, RNA interference (RNAi)

Primary Literature

Accorsi, Alice, Monique M. Williams, Eric J. Ross, Sofia M. C. Robb, Sarah A. Elliott, Kimberly C. Tu, Alejandro Sánchez Alvarado. “Hands-On Classroom Activities for Exploring Regeneration and Stem Cell Biology with Planarians.” The American Biology Teacher 79, 3 (2017): 208–223. https://doi.org/10.1525/abt.2017.79.3.208.