SIZING UP DNA
DNA restriction analysis is a fundamental concept in the field
of biotechnology. Learning the techniques and protocols involved in restriction
analysis can be made more interesting and meaningful if placed in the context
of a murder mystery simulation. This lesson and video introduces students
to the process of electrophoresis and restriction enzymes and the equipment
involved in DNA fingerprinting.
The lesson can be followed by an actual simulation if equipment is available.
NOVA: Murder, Rape, and DNA
- understand the functions of the equipment used in DNA restriction
- recognize and understand the following words: electrophoresis, restriction
- be able to analyze DNA fragments to determine size.
- be able to differentiate between the usage of standard vs. semilog
- Student Worksheet
- Crime Scene Lab Sheet (optional)
- Restriction Digest Gel or Photograph
- Sizing-up DNA Sheet
- Semi-log Graphing Paper
- Metric Ruler
Show students samples of the equipment used in the study of
DNA fragments. Students will be provided with a worksheet picturing the
equipment. They will write a description of what they believe each of the
pieces is used for. Ask the students, "Can you tell, by just looking,
how each of these objects are used?"
View NOVA: Murder, Rape, and DNA
Segmented viewing: The video should be cued 40 minutes into the program.
Find the segment where scientists are shown using electrophoresis equipment
as part of a murder mystery. Provide the students with a brief background
of information about the video prior to this segment. START the tape
at the where Pitchfork's impersonator is having a blood sample drawn. After
the blood is drawn, the technicians perform tests. Show the segments with
the sound off which allows students to visually focus on the equipment and
how it is used. PAUSE after each piece is shown in use. Direct students
to record functions. STOP the segment when the completed DNA fingerprints
are shown (about 3 minutes).
Second viewing: REWIND and show the same segment again, this
time with the sound on. Direct the students to focus on listening for the
vocabulary terms on their worksheet. Tell the students to raise their hands
when they hear each word defined. Teacher pauses after each term has been
defined to allow students to write definitions.
Teacher will facilitate discussion concerning the functions
of the biotechnology equipment and the definitions of the terms electrophoresis
and restriction enzymes. as demonstrated in the video.
Sizing - Up DNA
The gel (or photograph of gel) shows samples of DNA from the bacteriophage
lambda, cut using agarose gel electrophoresis. The DNA samples were loaded
into the wells (holes) in the agarose gel and electrophoresed. An electric
field applied across the gel causes the DNA fragments to move from the wells
through the gel, toward the positive electrode. Smaller DNA fragments migrate
faster than larger ones, so the fragments of differing size become concentrated
in separate bands. The characteristic number and pattern bands produced
by each restriction enzyme could be a "DNA Fingerprint".
Classes performing lab with actual gels will have five lanes of fragments
(fingerprints), while those using a photograph will have four. In either
case students will graph lane #3, read from left to right with the wells
at the top. Lane #3 in each case contains lambda DNA cut with HIND III enzyme.
Students can use this information from this graphing to interpolate fragment
size for each of the other lanes.
Crime Scene Simulation
#1 #2 #3 #4 #5
Please Note:THESE WORDS SHOULD LINE UP VERTICALLY UNDERNEATH EACH #
DNA restriction analysis is a fundamental concept and practice in recombinant
DNA technology. The ability to cut DNA predictably and precisely enables
scientists to manipulate and recombine DNA. The discrete bands of like-sized
DNA fragments in each lane shows that each of the DNA molecules present
in each restriction digest were all in precisely the same place (a fundamental
concept behind DNA fingerprinting).
Direct students to research and contact biotechnology companies
operating in locally or nationally. Some companies will allow their scientists
to correspond with students. Determine what special academic preparation
is needed for a career in this field.
Contact and interview forensic scientists who collect evidence at the crime
Research topics for students include:
- Students can research a broad diversity of topics in biotechnology
by visiting the About Biotechnology site on the internet. The site has categories
- Biotech chronicles
- Unlocking the technology
- Putting the science to work
- The career center
- The graphics gallery
1. Describe the historical development of
2. What are the current techniques, methods, and
equipment used in biotechnology?
3. How is biotechnology currently being used and developed in science, agriculture,
medicine, and industry?
4. What career opportunities exist in the field of biotechnology? How does
a student prepare for this job market?
Research projects for students include:
- BioOnline: Biotechnology On The 'Net provides students with resources
to investigate the corporate world of biotechnology. Listings include name,
location, and product line of corporations involved in the biotech industry.
Information on this site includes government, research, and educational
applications of biotechnology.
1. List the 10 corporations which are located closest to your school. Include
their names, location, product, and general description of the company.
2. List 10 career opportunities available in the biotech industry. Include
a brief job description and the educational requirements of the job (students
may also use About Biotechnology listed in extension #1).
BioOnline: Biotechnology On The 'Net
Transcripts of the OJ Simpson case are currently available on-line.
- Use Court TV on-line services to determine the legal status of DNA
fingerprinting use in the courtroom.
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