Many students studying DNA structure do not understand or cannot fully visualize the concepts of complementarity, antiparallel, and the organization of the 5’ and 3’ ends of a nucleotide strand. Here, a method that works very well to get students actively involved in the process of describing a DNA molecule is described.   Students themselves are used as the nucleotides in this activity. 

Intended Audience

9-12 X

Learning Objectives

By completing this activity, the student will be able to:


  1. describe and diagram DNA structure using the following words: complementary and antiparallel.
  2. describe the components of a nucleotide,
  3. label a nucleotide’s 5’ and 3’ end,
  4. label the ends of a string diagram of DNA with 5’ and 3’,
  5. knowing one of the ends of one of the strands.
  6. diagram a complementary strand of DNA given the other strand.

Necessary Student Background

Students should have prior knowledge about DNA’s role as the genetic material and about the double-helical nature of the DNA molecule. General knowledge about the process of DNA replication, transcription, and translation is also helpful. Additionally, students should:

be familiar with the structure of nucleotides in terms of their sugar, phosphates, and base. 
·        be able to identify the sugar, phosphates, and base of a nucleotide. 
·        understand why the carbons of organic molecules are numbered. 
·        be familiar with Chargaff’s rules. 
·        be able to explain hydrogen bonding and base pairing.


DNA structure, Nucleotide, Purine, Pyrimidine, Antiparallel, Complementarity, 5’ (five prime), 3’ (three prime), Chargaff’s rules

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Modeling Concepts of 5’, 3’, Antiparallel and Complimentary in DNA Structure (14 pages)