|
|
Cracking the Code of Life
|
|
|
|
Classroom Activities
|
Objective
To help students understand the process involved in sequencing the
human genome.
-
two sets of the "Mystery Message" student handout, cut in
different locations (PDF
or
HTML)
- scissors
- clear tape
- slide of cheek cells stained with methylene blue
-
Before class, copy two sets of the
Mystery Message student handout
for each group. To prepare the sets for the activity, first cut
out each column of letters. Next, attach them so that the symbol
at the bottom of one column matches up with the symbol in the
adjacent column. Once the symbols are matched up, cut out the
symbols and use clear tape to join the two pieces together so
that there is no space in between the letters. Continue this
until you have one long sequence.
-
Using a pair of scissors, cut the sequence of letters at four or
five random locations. Do the same with the second sequence of
letters, but make sure to cut the second sequence at
different locations than the first. (You may want to laminate
the cut pieces so you can use them again.)
-
Carefully fold and place the two sets of fragments of the
message in a plastic bag. Organize students into groups and give
one bag to each group.
-
Tell students that to sequence the genome, scientists decided to
cut up into small pieces all the chromosomes that make it up.
These pieces, then, could be sent to different research teams to
be sequenced, or decoded. These decoded pieces are represented
in the cut-up series of letters in each group's bag.
-
Now comes the challenge: The genome needs to be put back
together so that scientists can read the entire sequence. In
each group's bag are all the pieces for one chromosome, but the
group needs to figure out the original order.
-
Have students work to find a technique that will allow them to
reconstruct the correct sequence of one chromosome. What was the
content of the message? What else, if anything, did students
note about the message?
In mapping the DNA sequence on a chromosome, scientists have found
it faster to divide and conquer. The 24 chromosomes in the human
genome (22 autosomes and the X and Y) are cut into many smaller
fragments. Each fragment is sent to a different research lab to be
sequenced. When the sequencing of these smaller fragments is
completed, a computer is used to find the overlapping regions and
put them into the correct order as found on the intact chromosome.
By overlapping sequences of letters, students should be able to
arrive at the secret message coded on the original strip. The final
message reads: "In order to speed up the sequencing of the human
genome scientists had to break each chromosome into pieces and then
overlap the pieces just as you have done in this aktivity"
Some students may notice that the final word in the sentence,
aktivity, is misspelled. Explain to students that this represents a
base-pair, or one-letter, mutation in the chromosome. Even a single
base-pair mutation can cause a genetic illness.
Books
Baker, Catherine.
Your Genes, Your Choices: Exploring the Issues Raised by Genetic
Research.
Washington, D.C.: AAAS, 1999.
Describes the Human Genome Project, the science behind it, and the
ethical, legal, and social issues raised by the project.
Marshall, Elizabeth L.
The Human Genome Project : Cracking the Code Within Us.
Minneapolis, MN: Econo-Clad Books, 1999.
Explores the process and technology used in sequencing a portion of
the human genome. A chance to see the process of science through the
eyes of the scientist. The author connects the discoveries in the
human genome with the ethical implications they pose for society.
Reilly, Philip R.
Abraham Lincoln's DNA and Other Adventures in Genetics. Cold
Spring Harbor, NY: Cold Spring Harbor Laboratory Press, August
2000.
Offers wide-ranging tales of crime, history, illness, and ethics to
illustrate principles and issues of human genetics.
Sayre, Anne. Rosalind Franklin and DNA. New York, NY: W. W.
Norton & Company, Inc., July 2000.
Offers a true life account of Franklin's work in elucidating the
structure of DNA and explores the difficulties often faced by women
in science. Franklin's research was central to the Nobel
Prize-winning discovery of DNA, and Watson and Crick's discovery
relied heavily on her pivotal X-ray crystallography data.
Watson, James D.
The Double Helix: A Personal Account of the Discovery of the
Structure of DNA.
New York, NY: Simon & Schuster, 1998.
Chronicles the original story behind the race to discover the
structure of DNA as seen through the eyes of James Watson.
Articles
Crick, Francis, and James Watson. "A Structure of Deoxyribonucleic
Acid." Nature. Volume 171. 1953, Pages 737-738.
The seminal paper on the discovery of the structure of DNA.
"Outlook 2000: Inventing the Future."
U.S. News & World Report, January 3, 2000.
Special double issue includes different articles about the Human
Genome Project, which explain how the secrets of DNA may help cure
illnesses and arrest aging, as well as outline the benefits and
perils of genetic testing.
Web Sites
NOVA Online—Cracking the Code of Life
http://www.pbs.org/nova/genome/
Provides program-related articles, interviews, interactive
activities, resources, and more.
Genes and Disease
http://www.ncbi.nlm.nih.gov/disease/
Shows what diseases have been mapped on which chromosomes. The Map
Viewer presents a graphical view of the available human genome
sequence data as well as cytogenetics, genetic, physical, and
radiation hybrid maps.
The Human Genome Project
http://www.genome.gov/10001772
Provides background information on the Human Genome Project from the
National Human Genome Research Institute. Several links provide more
detailed resources describing the history and goals of the Human
Genome Project.
Genetics Resources
http://www.library.vcu.edu/tml/bibs/genetics.html
Offers list of links with descriptions to more specific subject
areas in the topic of genetics and medicine.
The "See Your DNA" and "Mystery Message" activities and the "Case
Studies" activities align with the following National Science
Education Standards:
Science Activities: Grades 5-8
|
Science Standard C:
Life Science
|
|
|
Reproduction and Heredity
Molecular Basis of Heredity
Case Studies: Grades 5-8
|
Science Standard F:
Science in Personal and Social
Perspectives
|
|
|
Science and Technology in Society
Case Studies: Grades 9-12
|
|
Science Standard F:
Science in Personal and Social
Perspectives
|
|
|
Science and Technology in Society
|
|
