Activity 3.1.4 Student Response Sheet
Part I: DNA Microarray Virtual Lab
1. Why are tissue samples from healthy and cancer cells taken from the same
patient?
a. It allows us to look at the differences in gene expression in cells that have
the exact same genetic blueprint (accounting for disease and not
differences in people).
2. Describe the process used to isolate mRNA from the other types of RNA.
a. Once the RNA is separated from proteins, DNA, and other cellular
components, wash the RNA samples over columns filled with small beads,
which only bind to mRNA. The other types of RNA will wash away, leaving
only mRNA.
3. Why is it necessary to make a cDNA copy? Why is mRNA not used?
a. A fluorescent label (markers) in the cDNA molecule allows us to visualize
the cDNA later on. mRNA is not used because it is less stable than DNA.
4. Draw and label a diagram of the process of how labeled DNA copies are made.
Your diagram should be in color.
© 2010 Project Lead The Way, Inc.
Medical Interventions Activity 3.1.4 Student Response Sheet – Page 1
5. What happens once you apply the DNA from the two samples to the DNA
microarray?
a. They pair up with their complementary DNA strands that are on the
microarray.
6. What does the red color indicate?
a. The red color indicates genes that are “turned up” in cancer (genes that
produce more mRNA in the cancer cells than in healthy cells) (cancer
cells).
7. What does the green color indicate?
a. The green color indicates genes that are “turned down” in cancer cells
(healthy cells).
8. What does the yellow color indicate?
a. The yellow color indicates mRNA that is made in both healthy and cancer
cells. It also indicates that the defects in cancer cells prevent the gene
from being translated into a protein and cannot be detected using
microarray analysis. (Therefore, it is probably not related to our study.)
9. What conclusions can you make from microarray data?
a. Microarray data analysis can determine which genes have been turned
up, have been turned down, or are not affected (present in both cells). It
can also determine whether or not the person expresses the trait.
10. What are the limitations of DNA microarray technology?
a. Defects in cancer cells that prevent the genes from being translated into
proteins cannot be detected using microarray analysis (exactly which gene
went bad to cause the cancer).
Part II: Lung Cancer Microarray Wet Lab
11. Use colored pencils or markers to draw what you observed in the microarray
experiment.
Errors:
Gene 2= purple, 1:1
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Medical Interventions Activity 3.1.4 Student Response Sheet – Page 2
12. Which gene(s) were expressed more in Grandpa Joe’s lung cells? How do you
know?
a. Genes 1 and 5: pink colored (cancerous)
13. Which gene(s) were expressed less in Grandpa Joe’s lung cells? How do you
know?
a. Genes 3, 6: blue colored (normal/non-smoker)
14. Were there any genes not expressed in either cell type? Explain why a gene
would not be expressed in either cell.
a. Gene 4
b. Neither cell codes for that protein (unrelated, not coded for protein in
lungs)
15. Explain what it might mean for a gene to be expressed the same in both Grandpa
Joe’s lung cell and a non-smoker’s lung cell.
a. That gene is not influenced by smoking and doesn’t present much risk for
cancer (codes for a protein they both need, like how to be a lung).
16. Which genes may play a role in causing cancer in lung cells? Explain your
choices.
a. Genes 1, 5, 3, 6
b. Dark pink/light pink colors and therefore are more expressed in cancer
genes
c. Turning up or down a protein-making process can cause cancer
17. Record your gene expression ratios for your microarray:
a. Gene 1-- 8:1
b. Gene 2—1:1
c. Gene 3—1:8
d. Gene 4—0:0
e. Gene 5—2:1
f. Gene 6—1:2
© 2010 Project Lead The Way, Inc.
Medical Interventions Activity 3.1.4 Student Response Sheet – Page 3