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Professor Program
Activity: Demonstrating the Antiparallel Nature of DNA
Activity Adapted for HHMI-UCI O’Dowds Professor Program by Adrienne Williams
Activity created by: Nicholas Acheson, Robert Brador, Ken Chapman, Suzanne Long and Carl
McAllister at ASMCUE May 2008.
See www.researchandteaching.bio.uci.edu for more information.
Activity Type: Student demonstration
Goals: To help undergraduates understand the importance of deoxyribose orientation
Abstract:
Describe orientation using one student
Help half of students to form one strand
Help second strand to form
Debrief, answer questions, emphasize importance
2 min
1 min
2 min
2 min
Time needed: 7 minutes
Materials needed:
1. An even number of students (at least 8).
2. Enough index cards with nitrogenous base letters (A, T, C or G) written on them for
each volunteer. Make sure each card has an appropriate matched base card (G-C and
A-T)
Before class:
1. Look over structure of DNA and RNA molecules
2. Plan how to gather volunteers, and bring tools to facilitate the gathering.
In class:
1. Ask for volunteers, or pass out numbered
cards or something so you can call students up
as needed.
2. Use first volunteer as a “sample” molecule.
Point out how standing with the right arm
straight in front represents the nitrogenous
base, and the left arm straight out to the side
represents the 5’ phosphate group. The right
shoulder represents the 3’ hydroxyl group.
3. Ask up three more volunteers.
4. Have them line up with the first volunteer to
form a single “strand” of DNA. Discuss
which is the 5’ end of the strand, and which is
the 3’ end. Give each person a “base” card to hold in his/her right hand.
5. Invite up four more volunteers, and give each a “base” card.
6. Have new volunteers determine how to arrange themselves to form the antiparallel
strand to the original strand. Try to let them work this out as much as possible. If
© 2007 by the HHMI-UCIrvine Professor Program. For non-commercial, educational use only.
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Professor Program
group is stuck, ask remaining seated class members
questions to help volunteers determine what to do
next. Minimize the “I don’t get it” embarassment for
the volunteers.
7. Once the antiparallel strand successfully binds to the
original strand, point out the difference in 3’ to 5’
orientation and pairing of bases.
8. Thank everyone for their help, and have them return to their seats.
Assessment ideas (how will you test understanding of the concept?)
What worked well / what should be changed for next time?
© 2007 by the HHMI-UCIrvine Professor Program. For non-commercial, educational use only.