Online College Courses for Credit

DNA Architecture

DNA Architecture


By the time you complete this tutorial, you should be able to:

  1. describe the molecular structure and configuration of the DNA molecule including:
    • the complementary base pairing that occurs,
    • the physical parameters of the molecule (diameter, distance b/w bp, # bases/turn),
    • antiparallel sugar-phosphate strands,
    • helical nature,
    • role of histones and structure of nucleosomes,
    • supercoiling.
  2. identify electron photomicrographs of DNA.
  3. distinguish clearly among DNA, chromosome, gene and allele.

Deoxyribonucleic Acid (DNA) is a molecular that is common to all forms of life on earth.  All living things have DNA with identical subunits:  thymine, adenine, cytosine and guanine. In all cases, these subunits carry the code to make proteins.  In addition, there is so much that we still need to uncover about the information stored in this molecule.

See More
Fast, Free College Credit

Developing Effective Teams

Let's Ride
*No strings attached. This college course is 100% free and is worth 1 semester credit.

29 Sophia partners guarantee credit transfer.

311 Institutions have accepted or given pre-approval for credit transfer.

* The American Council on Education's College Credit Recommendation Service (ACE Credit®) has evaluated and recommended college credit for 27 of Sophia’s online courses. Many different colleges and universities consider ACE CREDIT recommendations in determining the applicability to their course and degree programs.


DNA Architecture & Packing

It is a testament to Rosalind Franklin's meticulousness that the measurements she made of the DNA molecule in the early 1950's are considered accurate today with the more sophisticated technology available! This tutorial explores these and other parameters of DNA architecture. Then, there remains the issue of how 2 m of DNA fits into a nucleus - so we will examine how DNA is packaged to fit - and still be actively used.

Source: M. O'Mahony, Open Source images, other images have citations with terms of use.

Student Notes Template

Template for students to use while watching tutorial video. Contains images used in video. Those that are not Open Source available have acknowledgment of permissions with them.


Source: M. O'Mahony, open source images, images used with permission

DNA packing - advanced

This is the same DNALC video linked to the notes EXCEPT for a more detailed description of the animation.

Source: DNALC

DNA: Protein Data Bank

Summary of DNA structure from the Protein Data Bank.


Source: Protein Data Bank, doi: 10.2210/rcsb_pdb/mom_2001_11