July’s
Curriculum
2014-2015
SHPE Jr. Chapter
STEM Activity
DNA Forensics
(Image: nih.gov)
Some simple advice:
• Be prepared. Test-drive the activity beforehand.
• Have all the required materials on hand.
• Keep students on track.
• Keep an eye on the clock and follow the time
frame.
• Be flexible and creative.
• Have fun!
DNA Forensics
Goal:
Students learn one of the tools developed by engineers to help solve
crime cases: DNA fingerprinting. Working in pairs, they do a simulated or
actual gel electrophoresis and see how DNA fingerprinting works to
identify differences between individuals.
Engineering/STEM areas:
Forensic engineering, biomedical engineering, electricity, chemistry,
genetics
Learning objectives
•
Understand how electrical current and fluid dynamics can be used to
separate substances
•
Learn how DNA fingerprinting works
•
Understand the role engineers can play in forensics and genetic
biosciences
DNA Forensics
Time:
45-60 mins
Suggested group size:
Pairs
Materials:
Materials depend on how you’ll do the activity. It can be done as a simulation using
food coloring as mock DNA. You can also do a real gel electrophoresis using a
setup made from household items and run a gel on either food coloring or actual
DNA extracted from fresh produce.
For either approach, you’ll want:
•
Student Resource Sheets, one per student (in lesson)
•
Student Worksheets , one per pair (in lesson)
•
If using food coloring, get either six different colors to two different brands (the
bottles can be shared among students).
DNA Forensics
Materials (continued):
To do the activity entirely as a simulation, each
pair of students gets:
•
•
•
•
•
•
•
Coffee filters cut into strips 1 cm x 8 cm, five or six
strips per pair
Scissors
Toothpicks
Water
Small beakers or clear drinking cups to hold water
Paper towels
Paper clips or tape (to secure strips of coffee filter
to cup or beaker)
DNA Forensics
Materials (continued):
To do a real gel electrophoresis:
Agar agar (preferably in powder form.
Can be found online or in Asian grocery
shops.)
•
Salt
•
Baking soda
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Distilled water
•
Aquarium pH test kit
•
•
•
Rectangular plastic containers, one small enough to fit inside the other
one OR enough Legos to make containers and plastic wrap to line them
Screws, wire, or other items that can be used to conduct current as an
electrode
An object to make small wells in the gel, such as a comb, plastic cutouts,
or the dots on Legos
DNA Forensics
Materials (continued):
Full instructions for making the gel electrophoresis, as well as extracting DNA if you
choose to do that, can be found here:
http://www.scq.ubc.ca/the-macgyver-project-genomic-dna-extraction-and-gelelectrophoresis-experiments-using-everyday-materials/
And here:
http://www.sciencebuddies.org/science-fairprojects/project_ideas/BioChem_p028.shtml#procedure
Alternately, you can purchase electrophoresis units online
from Carolina Biological:
http://www.carolina.com/biotechnology-teachingresources/dna-gel-electrophoresis/dna-gel-electrophoresiskits/10126.ct
DNA Forensics
Before the activity:
•
Read through both the student and instructor resources so you have the
background information
•
Gather all the necessary materials.
•
Add information about available building materials to the Student Worksheet
•
Make enough copies of the Student Resource so that each student has one
•
Make one copy of the Student Worksheet per group, plus a few extras
•
Run through the activity once to familiarize yourself with it and the results you
can expect
DNA Forensics
Background in the Student Resource
Many people convicted of crimes before the invention of DNA fingerprinting
in 1985 have been freed by DNA evidence.
DNA fingerprinting relies on differences between individuals’ DNA
•
DNA is written with four different bases, represented by the letters A, G, T, and
C
•
Two people can have a working gene that differs by only one letter in this code
•
Special enzymes can cut DNA when they find certain letter sequences. This
means that the DNA of different individuals will be cut into different size pieces.
Investigators compare DNA samples using gel
electrophoresis
•
Chromatography is the process of separating particles
in a solution based on their differing sizes, charges, or
other characteristics
•
Gel electrophoresis is a type of chromatography that
uses electrical charge to move charged particles
through a gel. The larger particles move more slowly.
•
Gel electrophoresis can be used to compare DNA
samples from different suspects.
Remember to read the Student Resources beforehand!
DNA Forensics
Activity procedure
•
Give students some examples of ways in which DNA is used in solving crimes. If there’s
been a news story featuring the use of DNA in a crime, bring that up. Other examples could
be using DNA as evidence in court, to exonerate a prisoner on Death Row, or to identify the
biological father of a child.
•
Ask students to hypothesize about how the DNA is analyzed in order to use it to identify an
individual. After they’ve come up with some ideas, tell them they’re going to see for
themselves how DNA is analyzed, and learn about one of the many roles engineers have
played in forensics.
•
Go over the information in the student resource, making sure that students understand the
concepts related to DNA, nucleotide sequences, and DNA as a charged molecule. If you
think your students have had biology (if they’re juniors or seniors), these concepts might be
elementary for them. If they are freshmen, you may want to leave extra time for this
discussion
•
Once your confident students understand the biology, explain briefly that a gel can serve as
a filter to separate particles based on their size. Let students know that they’ll learn how this
happens once they’ve set up their gels (real or simulated).
DNA Forensics
Activity procedure (cont’d)
•
Explain that food colorings are combinations of different pigment molecules and that these
pigment molecules have differing sizes, just as chopped-up DNA molecules have different
sizes. Tell students that they’ll be doing a process on the food coloring that’s similar to
running a gel, but without the need for electricity. They will be separating pigment molecules
by size, and the groups of molecules will be clearly identifiable by their color.
•
Distribute materials and Student Worksheets to each pair of students.
•
Ask students to study bottles of a few different colors and hypothesize what pigments make
up the color in the bottles. What pigment colors, for example, do they expect to find in the
bottle of blue coloring?
•
Tell students to follow the instructions in the resource, putting a single drop of a color 2 cm
from the bottom of a filter strip. They should do this with five filter strips, each dotted with a
different food color.
•
Students then fill their cups with 1 cm of water. They should wipe down any water on the
inside walls of the cup.
DNA Forensics
Activity procedure (cont’d)
•
•
Students then put the filter strips into the cup or beaker. It’s very important that the dots of
pigment are above the surface of the water. Use paper clips to attach the filter strips to the
edge of the cup or beaker, so that they don’t fall in.
While the “gels” are running, go over how gel electrophoresis works to separate substances
based on particle size by using charge to move the particles. (If you’re doing the simulation,
explain that the water moves up the filter by absorption rather than charge).
•
If there is spare time at this point, direct students to answer questions on the Student
Worksheet
•
After 10-15 minutes, tell students to check their gels, comparing the different strips. As a
class, compare results that different pairs got.
•
Tell students that pairs should split up and each student find a different partner to discuss
the questions on the Student Worksheet with. If there is sufficient time, discuss the answers
as a class.
DNA Forensics
Assessment
•
All students should provide answers to the questions in the Student
Worksheet.
DNA Forensics
Extensions
•
Explore other ways that engineering and forensics intersect.
•
Have students use the results to identify relationships between biological organisms,
rather than solve a crime
•
Research the history of DNA fingerprinting and why it’s been controversial in the past,
and how engineers have improved its accuracy. Hold a class discussion of whether or
not DNA evidence is enough to convict and/or free someone in the absence of other
physical evidence.
DNA Forensics
Teaching tips
•
Take the reins on dividing the class into student groups (rather than letting students
decide). If you know your students, try to be sure that each group has a balance of
personalities, with a mix of outgoing and more introverted students.
•
Circulate around the classroom as students are working and be sure to keep them on
track, answer questions, and encourage students who are less assertive.
•
Some groups will be more active and will immediately dive into the project. Others will be
more reticent. Keep each group moving along. Be sure to answer any questions relating
to understanding chromatography and electrophoresis.
•
Encourage students to think roofs they have seen in photos of places where people don’t
have access to manufactured roofing materials.
DNA Forensics
Takeaways:
•
Engineers play an important role in developing forensics technologies
Gel electrophoresis and other technologies have been invented by engineers working
with chemists and geneticists. Bioengineers invent methods to make precise cuts in DNA
using special enzymes.
•
DNA from different individuals can be cut into pieces of different sizes that can be
used to identify an individual
Fully functional genes can differ very slightly from one person to the next, and these
slight differences can be used to match a DNA sample to the individual it’s from.
•
Chromatography is a way of separating particles in the fluid by size, charge, or
other characteristics.
Smaller particles will move through a substrate faster than large particles. This method
can be used to separate many mixtures for different purposes. When using
chromatography to separate pieces of DNA, the resulting banding pattern can be
matched to a DNA sample from a specific person.
DNA Forensics
Resources and bibliography:
•
Teach Engineering: DNA Forensics and Color Pigments
https://www.teachengineering.org/view_curricularunit.php?url=collection/uoh_/c
urricular_units/uoh_dna/uoh_dna_curricularunit.xml
•
My Science Box: DNA Fingerprinting
http://www.mysciencebox.org/DNAfingerprint
•
The MacGyver Project: Genomic DNA Extraction and Gel Electrophoresis
Experiments Using Everyday Materials
http://www.scq.ubc.ca/the-macgyver-project-genomic-dna-extraction-and-gelelectrophoresis-experiments-using-everyday-materials/
•
Differences between crime lab analysts and forensic engineers
http://work.chron.com/differences-between-crime-lab-analysts-forensicengineers-14613.html
•
Biotech Project activities for high school
http://biotech.bio5.org/activities
DNA Forensics
Which suspect dunnit?
Questions?
Contact Robin Marks
Discovery Street Science
discoverystreetscience@gmail.com
Adapting to a
changing
world
MODULE 9: MANAGING CHANGE
Agenda
• Welcome and introductions
• Adapting in a changing world
• ACTIVITY: Our Changing World/My Changing World
• Tips for managing change
• College Planning Checklist
• Questions and Answers
Welcome &
Introductions
Adapting in a
changing world
Things do not change; we change.
-Henry David Thoreau
Adapting in a changing world
•
•
•
Change is inevitable.
During your lifetime, you will experience change in
almost everything around you (including new
technologies, environmental change, healthcare,
education changes, new friends, college experiences,
etc.).
You must be prepared for change.
•
Your ability to adapt to change will help you be
successful.
•
Today, we will explore change around us and how to
adapt.
Activity
OUR CHANGING WORLD/MY CHANGING
WORLD
Our changing world/my changing world
•
You will receive a 5x7 index card.
•
Number your card with a #1 and #2 and leave space
to write a couple sentences for each
•
#1 – List one thing in society that you would like to
change (Example: Racism, lowering the drinking age)
•
#2 – List one thing you would like to change about
your own academic behavior (Example: Be a better
note taker, raise my GPA, make an “A” in biology)
•
Do not put your name on your card
Our changing world/my changing world
•
The session facilitator will shuffle the cards and
redistribute them so you do not have your own card
•
Break into small groups and read each card aloud
•
Choose the areas of change from #1 and #2 that you
would like to explore more
•
Right five actions steps to make that change happen;
identify a group scribe to write down the answers and a
group presenter who will share with the class what you
have decided
•
The action steps must be useful, reasonable, and
doable
Activity Wrap-up
• What are some of the key takeaways from these
conversations you will remember from today?
• Is it hard to change the world? The nation? Your
community? Yourself?
• What are the major changes involved with making the
transition from high school to college? What action
steps can you take to make it easier?
Tips for
managing
change
Tips for managing change
•
Do your research
•
Weigh the pros and cons
•
Outline all of your possible action steps
•
Trust your instincts
•
Don’t be afraid to ask for help and advice
•
Your attitude about change can make a big
difference on the outcome
College
Planning
Checklist
College Planning Checklist
• Seniors
Finalize your financial aid
Contact your roommate
Register or attend orientation
Send your final transcript to the college you plan to
attend
• Start research student organizations you may be
interested in joining
• Find out the name of the SHPE Chapter President at your
future college
•
•
•
•
• Freshmen to Juniors
• Sign up for a summer camp
• Challenge yourself to read at least one book each month
Questions and
comments
F OR M OR E IN F OR M AT I ON A BOU T T H I S M OD U L E,
E - M AIL H IN OJ OSACONSULT ING@GMAIL.COM