Download Muscle Stem Cells

Biology- ROOM 345
Cell Differentiation
Name_______________________________
Day 1-Day 3 of development:
Congratulations! Fertilization has occurred, and your organism is on its way to becoming an embryo. Currently,
your organism is a zygote, which is simply the fusion of one egg and one sperm. Obtain a golf ball-sized piece
of Light Pink play-doh to represent your zygote.
1. Humans are multicellular (approximately 10 trillion!) organisms. How will your zygote become a 10
trillion-celled human?
Through the process of mitosis, your zygote will become an 8-celled morula. Turn your zygote into a morula
using the process of mitosis you just learned.
2. Summarize the steps of mitosis below.
3. Are all of the cells in your morula genetically identical or different? Defend your answer.
Day 4 of development:
Replace 2 cells of your morula with Blue play-doh. This will become your organism’s placenta. Replace the
remaining 6 cells with Red play-doh. This will become the embryo itself.
4. What do you think the term “cell differentiation” means?
Demonstrate cell differentiation by replacing each of the 6 cells of your embryo, according to the following:
2 cells with Yellow play-doh will become ectoderm.
2 cells with Dark Green play-doh will become mesoderm.
2 cells with Dark Purple play-doh will become endoderm.
5. These three types of cells make up what are called “germ layers.” Research these layers and describe
how they will further differentiate.
Use the process of mitosis to help your embryo continue to develop into a 32-cell morula. Nature tends to deal
harshly with mistakes in embryo development (yes, that means your embryo dies). Therefore, show your
teacher when you are finished!
Day 5- Day 8 of development:
Your morula is continuing to develop through the process of mitosis. Divide your 32-cell morula into a
blastocyst. A blastocyst is composed of 128 cells and is the stage in which implantation occurs.
6. Are all of the cells in your blastocyst genetically identical or different? Defend your answer.
7. How many of each of the following cells does your blastocyst contain?
a. Placental:
b. Embryonic:
Demonstrate cell differentiation by replacing you embryonic cells in the following way:
Ectoderm:
Half will become neural stem cells. Use Hot pink play-doh.
Half will become skin stem cells. Use Brown play-doh.
Mesoderm:
Half will become muscle stem cells. Use Orange play-doh.
Half will become blood stem cells. Use Mint Green play-doh.
Endoderm:
Half will become pancreas stem cells. Use White play-doh.
Half will become intestinal epithelial stem cells. Use Pink/Purple play-doh.
8. Why is it important that cell differentiation is occurring in your embryo?
Day 8- Birthday!:
All of the differentiation that has occurred and will continue to occur in your embryo is not random. Different
genes, hormones, cell interactions, and cell movements control the differentiation process. Essentially, this tells
each cell in your embryo which parts of its DNA will be “turned on” (expressed) or “turned off” (suppressed).
You will roll a die to represent these differential signals. Use the following tables on the next page to determine
the fate of each of your blastocyst’s embryonic cells! Record your results below.
Neural Stem Cells:
If you
roll…
1
Pancreas Stem Cells:
If you
roll…
1
2
Then the cell will differentiated into
a…
Motor Neuron (transmits movement
impulses)
Photoreceptors (detect light)
2
Then the cell will differentiated into
a…
Alpha Cells (regulates blood sugar
levels)
Beta Cells (regulates blood sugar levels)
3
ROLL AGAIN!
3
ROLL AGAIN!
4
Sensory Neuron (detects stimuli)
4
Delta Cells (regulate nutrient absorption)
5
Oligodendrocytes (aids in nerve
impulses)
ROLL AGAIN
5
Gamma cells (suppress appetite)
6
ROLL AGAIN
6
Skin Stem Cells:
If you
roll…
1
Then the cell will differentiated into
a…
Hair follicle cells
2
Hair follicle cells
3
Cheek cells
4
Cheek cells
5
Sebaceous gland cells (secrets oils)
6
Sebaceous gland cells (secrets oils)
Blood-Forming Stem Cells:
If you
roll…
1
Then the cell will differentiated into
a…
Erythrocytes (red blood cells)
2
Macrophages (white blood cells)
3
ROLL AGAIN!
4
Neutrophils (white blood cells)
5
Platelets (blood-clotting cells)
6
ROLL AGAIN
Muscle Stem Cells:
If you
roll…
1
Then the cell will differentiated into
a…
Cardiac Muscle cell
2
Cardiac Muscle cell
3
Skeletal Muscle cell
4
Skeletal Muscle cell
5
Smooth Muscle cell (muscles lining
internal organs)
Smooth Muscle cell (muscles lining
internal organs)
6
Intestinal Epithelial Stem Cells:
If you
roll…
1
Then the cell will differentiated into a…
2
Columnar Cells (absorbs nutrients)
3
ROLL AGAIN!
4
Enteroendocrine Cells (produce hormones)
5
Paneth Cells (aids in digestion)
6
ROLL AGAIN
Goblet Cells (secretes mucus)
9. Could a muscle stem cell become a hair follicle cell? Why or why not?
10. A. Why would scientists be interested in researching stem cells?
B. At what point in the cell differentiation process, do you think scientists would have more potential
for research? Explain.
C. What could be some of the pros and cons of embryonic stem cell research?
Pros
Cons
11. Through continued cell differentiation and mitosis, your blastocyst will develop into a fetus. Will all of
the cells in your fetus be genetically identical or different? Explain.
12. On a separate piece of paper, DESCRIBE how multicellular organisms develop from one cell to
trillions of different cells, then ANALYZE why the results of these processes are important to
organismal survival. (This should be at least two paragraphs)
Stem Cell Differentiation
Embryonic Stem Cell