MODULE 2
Objective 2.2 Lesson B
VNTR (Variable Nucleotide Tandem Repeats)
To Catch a Thief
Course
Advanced
Biotechnology
Unit
DNA Analysis
Rationale
VNTRs were an important source of RFLP genetic markers used in linkage
analysis (mapping) of genomes. Now that many genomes have been
sequenced, VNTRs have become essential to forensic crime investigations,
via DNA fingerprinting and the CODIS database.
Essential
Question
How are VNTRs
detected and
used in DNA
Analysis?
TEKS
130.364 1A-K,
2E, 2G, 2H, 2J,
7H, 9A, 9F
TAKS
Science 1A, 2A,
2B, 2C, 2D
Prior Student
Learning
DNA structure,
micropipette,
electrophoresis,
restriction
enzymes, PCR
Image from: http://www.cstl.nist.gov/div831/strbase/fbicore.htm
Estimated
Time
2 hours
Wet lab requires
4 hours
Copyright © Texas Education Agency 2012. All Rights Reserved.
Objectives
Students will:
• Explain how VNTR analysis is used in DNA analysis.
• Model the steps taken to create a DNA Fingerprint.
• Complete the lab portion, learning to:
o extract DNA from cheek cells.
o set up a PCR reaction tube with all required components.
o operate a thermal cycler.
o make and load an agarose gel.
o interpret the finished gel and evaluate the quality of
amplification.
Key Points
I. See Module 2 Objective 2 Power Point.
Teachers' Domain
(http://www.teacher
sdomain.org/) is a free
digital media service for
educational use
from public broadcasting
and its partners.
Engage
Forensic DNA Video
 http://www.teachersdomain.org/resource/tdc02.sci.life.gen.sheppard/
 This video segment from NOVA: "The Killer's Trail" follows a team of
experts as they investigate the forensic evidence from the 1954 murder
of Marilyn Sheppard, one of the most famous unsolved crimes in U.S.
history.
 Have students read the background essay and answer the discussion
questions.
Activity
1. Pre-Lab Activities (2 options)
a. Internet: Students complete the “DNA Fingerprinting Web Activity.”
This provides some history and real world applications of DNA
fingerprinting.
b. Reading: Student read “How DNA Evidence Works”
(http://www.teachersdomain.org/resource/tdc02.sci.life.gen.howdnaevi
dence/) and answer discussion questions provided on the webpage.
2. Lab (2 Options):
a. Paper Model: http://cibt.bio.cornell.edu/labs/dl/HCAT.PDF
b. Wet Lab: “Amplification of D1S80 VNTR Loci by PCR”. Your district
approved science vendor can provide you with ordering information.
i. Use VNTR Lab Skill Assessment throughout the lab.
ii. By this time in the course, students should be able to execute
and troubleshoot all lab procedures independently.
Copyright © Texas Education Agency 2012. All Rights Reserved.
Materials
• Worksheet: “DNA Fingerprinting Web Activity”
• Article: “How DNA Evidence Works”
• Lab Handout: “Amplification of D1S80 VNTR Loci by PCR”
• VNTR Lab Skills Assessment
• Assessment Questions: Use the images to create test questions.
Assessment:
• Correct student responses to “DNA Fingerprinting Web Activity”
• Correct student responses to Results and Analysis Questions
• Student lab performance measured VNTR Lab Skill Assessment
• Sample assessment questions
Accommodations for Learning Differences
 Visit the Special Populations section of the CTE Career and
Technical Education Website: http://cte.unt.edu/special-pops.
National and State Education Standards
Texas College and Career Readiness Standards
I. Nature of Science: Scientific Ways of Learning and Thinking
C1, C2, C3, D1, D2, D3, E1, E2
II. Foundation Skills: Scientific Applications of Mathematics
A2, A5, A7
III. Foundation Skills: Scientific Applications of Communication
A1, B1, B2, B3, D1
Copyright © Texas Education Agency 2012. All Rights Reserved.
DNA Fingerprinting Web Activity
Name:_________________
1. Go to http://www.dnai.org/d/index.html and click on “Human Identification” and then on
“Profiling” and answer the following questions. Click on the button “DNA variations and
fingerprints.” Then click on button “A DNA variation.”
2. The acronym VNTR stands for ________________________________________________.
3. The acronym STR stands for _______________________________________________.
4. A locus is described as 4/10. What does this mean?
5. What types of markers are used in DNA typing?
6. Click on the button “The first DNA “fingerprints”” (next to the DNA variation button). What did
Jeffreys restrict?
7. Assuming that Jeffreys used the same restriction enzymes to restrict the genomes of different
people, what would cause differences in length of the fragments?
8. Why is Southern Blotting necessary in DNA fingerprinting?
9. The first gel that shown in the animation has a full smear going down both lanes. Why?
10. How did Jeffrey’s identify the location of polymorphic VNTRs in the smear?
11. The results are visualized by:
12. What is the advantage of using single-locus probes?
13. How many radioactive probes are bound in lane A in the D1S80 locus gel?________ How many in
lane B?_______ Why is there a difference?
14. Explain briefly how you would create a VNTR profile from a tissue sample.
Copyright © Texas Education Agency 2012. All Rights Reserved.
15. Click on “Today’s DNA profile”. Where are STRs located?________________________ How many
STRs does the FBI test? ________
16. How is PCR useful in detecting STR differences?
17. Interpret the computer output for the “blue” channel.
18. What is meant by a “random match probability”?
19. Calculate the probability of a person of Asian descent inheriting 10/11 for D8S1179.
20. Draw a picture that summarizes the steps the FBI uses to create a DNA fingerprint, starting from a
tissue sample.
Copyright © Texas Education Agency 2012. All Rights Reserved.
VNTR Lab Skills Assessment
Skill
Unacceptable
(0 points)
Beginning
(2 points)
Name:_____________________
Proficient
(4 points)
Advanced
(5 points)
Extract DNA
from cheek
cells
Set up a PCR
reaction with
all components
Operate a
thermal cycler
Make and load
and agarose gel
Interpret the
finished gel
Evaluate the
quality of
amplification
Teacher Comments:
Total Points: ________
Copyright © Texas Education Agency 2012. All Rights Reserved.
Teacher
Comments