In this activity, students learn how cell specialization takes place
in vertebrate embryos. They begin by exploring a gallery of different
kinds of specialized cells. They also explore how white blood cells are
specialized to fight viruses. They learn about the role of master control
genes in cell development. Finally, they learn about the significance of
-- and controversy surrounding -- stem cell research, and then analyze
the different points of view in the stem cell debate.
1.
Have students explore the
Gallery of Cells
stills and the Immune Cells in Action video
and note the kinds of specialization cells undergo. Ask:
- How have each of these cells (red blood, epithelial, muscle, liver, bone, neuron, and immune cells) become specialized
to perform a specific function?
2.
Ask students to consider the following question while they watch the
The Embryo Takes Shape video:
- If each cell has identical DNA, how do you think
a cell becomes specialized?
3.
Show the The Embryo Takes Shape video.
Discuss the following:
- What directs the sequence of events that turn a blob
of cells into an embryo with specialized
tissues and organs?
- The narrator says that "cells talk to each other."
What does that mean?
- How do cells in different parts of the embryo become
different kinds of cells and organs?
- What kinds of proteins are found in different cells
and organs?
- What tells the cells which kinds of proteins to make?
- What is the relationship between DNA, genes, and the
proteins that are produced in cells?
4.
Show the Gene Control video.
Discuss the following:
- What is the role of control genes?
- What kinds of chemicals do you think the mother
deposits on the egg?
- How do you think they might "turn on"
the control gene?
5.
Show the Genetic Tool Kit video.
Discuss the following:
- What do homeobox genes code for in animals?
- Why are homeobox (also called homeotic) genes called
the master control genes, or master switches?
- What other organisms besides fruit flies have homeobox
genes?
- What does the presence of homeobox genes in fruit
flies and mice indicate about their evolution?
- What does the presence of homeobox genes suggest
about the evolution of different eyes in different
organisms?
6.
Show the Stem Cells Breakthrough and the Stem Cells: Seeds of Hope? videos,
and have students explore the
Stem Cell Debate Web activity.
Discuss the following:
- Why are stem cells considered so valuable for medical
research?
- What are three sources of stem cells and the advantages
and disadvantages associated with using each?
- How might a stem cell be used to treat a disease such
as diabetes?
- What issues surround the debate over government funding
of stem cell research?
- What issue do you think needs to be debated as we make
decisions about stem cell research?