THE ULTIMATE CLUE, MY DEAR WATSON: DNA FINGERPRINTING
Students learn practical applications of DNA profiling in today's
forensic science and the future's many possibilities. While viewing the
video, students delve into the problems of extracting ancient DNA from fossils.
These molecular biologists use DNA profiling to sequence pieces of the dinosaurs'
genome. After viewing the video, students will simulate DNA profiling with
electrophoresis gel to solve a possible baby mix-up at the hospital.
NOVA: The Real Jurassic Park
Students will be able to:
- Explain the steps of DNA Profiling
- Describe the possible usefulness of DNA Profiling to our society
- Contrast extracting ancient DNA from fossils to modern DNA from blood
and other cells of organisms.
Per group of two:
- Copies of the lab "Will the Real Baby Smith Please Speak Up!"
- Glue or tape
To prepare students for the video, explain the steps of extracting
and profiling DNA. Explain how DNA is extracted and isolated from cells.
Cell membranes are lysed with detergent. The detergent will dissolve the
lipid component of the cell membrane and expose the protein and nucleic
acids. DNA must be extracted at a temperature range of 50°-60°
Celsius. Temperatures exceeding 60° C may denature the DNA. DNA must
then be placed in ethanol because it is soluble in aqueous solutions.
For an interesting demonstration of extracting DNA, purchase 1 DNA spooling
Kit. This laboratory activity allows students to extract DNA from salmon
sperm. The students will add ethanol alcohol to the sperm solution and precipitate
DNA by spooling it onto a stirring rod. The students are delighted. Request
Sigma product D-8666: 1 kit $18.90 from: Sigma Chemical Company PO Box 14508
St. Louis, MO 63178-9916 (800) 325-3010)
Explain how DNA is cut with restriction enzymes, run through an electrophoresis
gel, and probed with a radioactive substance, which appears on the film.
Many different restriction enzymes are available, and scientists choose
the one that will cut the DNA in the appropriate place in the sequence.
Each person has a slightly different sequence and when probed with radioactive
substances will produce a unique set of bands.
Ask the students for possible uses of DNA profiling. Have students bring
in news articles of recent court cases that use DNA fingerprints as evidence.
Another use of DNA profiling is to locate genes in our human genome. Once
these genes are found, they can be isolated and possibly inserted into people
whose genes are not functioning properly. Discuss the possibilities with
cutting out dysfunctional genes and inserting functional ones to cure a
disease. If there is time, distribute "Designer Genes" worksheet
and hold a mock trial or debate about the moral implications of such genetic
engineering. Discuss probability, a branch of math that predicts the occurrence
of chance events. Give students statistics for DNA testing in various court
cases and have them predict the chances of two people having similar bands.
To give students a specific responsibility while viewing, have
them write down each hurdle scientists must overcome to extract and sequence
a dinosaur's DNA (4 billion base pairs!) Ask if they believe Jurassic Park
could become a reality some day.
BEGIN the NOVA video "The Real Jurassic Park".
PAUSE when Jeff Goldblum says, "Jurassic Park has left me wondering
if we will ever see dinosaurs in the zoo someday." Ask the students
the same question again, "How many of you believe that someday Jurassic
Park could become reality?" RESUME the video.
PAUSE after Michael Crichton speaks about his book. Discuss what
is meant by a genetically engineered dinosaur. RESUME the video.
PAUSE after Step 1 Find Dinosaur DNA. Contrast uses and accessibility
of obtaining DNA from modern living organisms to that of dinosaurs' fossils.
As students watch the rest of this segment, have them write down all problems
that must be overcome just to extract and assemble the DNA from dinosaur
fossils. (Small organisms the size of a pin-point, range of species of dinosaur
DNA in insect's stomach, trying to figure out which species the DNA came
from, and if found in the bones, they must be well preserved) RESUME
video. PAUSE when Poinar Jr. holds up the gel sheet and points to
the DNA bands. Explain that this is a DNA profile film that was discussed
in previewing. RESUME the video. PAUSE after the color of
ancient DNA and modern DNA is shown when the female scientist takes them
out of the freezer. Discuss the viability of the DNA that is only 13,000
years old compared to 100 million years old dinosaur DNA. Ask "What
do you think happens to DNA over one million years?" RESUME
STOP the tape after John Horner shows the jaw of a rapter and discusses
manipulating eggs and sperm. Discuss on and off switches for genes in our
bodies. Tie this into prenatal care and how important it is to allow off
genes to stay off and on genes to come on. Drugs and alcohol can effect
this delicate balance and cause diseases or deformities. On a positive note,
genetic engineers may learn to turn on genes that code for important proteins
such as insulin. This could rid a person of diabetes.
To prepare students for the lab activity " Will the Real
'Baby Smith Please Speak Up" review the processes of DNA extraction
and DNA profiling. Discuss how DNA is separated in gel solutions. Gel electrophoresis
is a technique which separates charged particles such as nucleic acids by
running them through an electrical field. The DNA segments (which were cut
by restriction enzymes) migrate toward the opposite charge at the other
end of the gel. The smallest fragments can travel or migrate through the
gel the fastest. A radioactive probe is then placed on the bands and comparisons
or conclusions can be drawn as to whose DNA fingerprint is more closely
Tell the students they will be simulating the process of DNA profiling in
the activity, "Will the real baby Smith Please Speak Up!" Explain
that a simulation allows students to understand each step of DNA profiling.
Students will simulate cutting the DNA with enzymes, running it through
the gel, attaching radioactive probes, and developing the film to see bands.
Have students predict the impact of biotechnology on their future
and place their ideas in a time capsule to be opened at their 10 year reunion.
Invite a genetic engineer into your classroom to share recent research being
performed. It is possible that he/she could bring in equipment to show how
the process of electrophoresis gel is used to analyze DNA.
Visit your local forensic lab to learn how DNA fingerprinting is useful
in solving crimes.
Have students write to local judges asking if DNA profiling has ever been
used to help solve crimes in their immediate area.
LANGUAGE ARTS/SOCIAL STUDIES: Finish viewing the NOVA tape "
The Real Jurassic Park". Invite the students to express their opinions
of bioengineering using the debate,"Should dinosaurs be brought back
to life and placed in modern society." Have students write arguments
to support their position. Share ideas the next day in class to spark a
debate. Have students prepare a combined argument to present to the Environmental
Protection Agency. If some students are unsure, have them represent the
Environmental Protection agency to make the final decision based on the
arguments presented by classmates. ("Exploring Jurassic Park",
The Science Teacher , November 1993, Simmons and Wylie)
ART/ENGINEERING: Have students draw or create a three dimensional model
of a dinosaur zoo for tourists to visit. Make sure the students research
appropriate habitat, food sources, space for size of dinosaur etc. Students
could use facts from Michael Crichton's book Jurassic Park for guidelines.
SCIENCE/SOCIETY: Take students to the library and look up recent articles
on breakthroughs in the Human Genome Project. Such diseases as Alzheimer's,
heart disease, and many other genetically inherited disorders are being
mapped by scientists internationally. After reading the articles, students
could predict the outcomes of such technology for the year 2100. Relate
this to vaccines and medicines that were not around 100 years ago.
Purchase SCIENCE SLEUTHS videodisc from VIDEODISCOVERY and have students
solve the mystery of the Forgotten Triplet. This is an interactive videodisc
that allows students to witness interviews, look at documents, and see results
of scientific tests such as DNA profiles to determine which person could
be the long lost triplet to share the inheritance.
Master Teachers: Suzanne Asaturian and Cindy Vernon
Lesson Plan Database
Thirteen Ed Online