- 01 Introduction
- 02 Biology of DNA
- 03 Practical Issues Specific to DNA Evidence
- 04 Introduction to the Forensic DNA Laboratory
- 05 Assuring Quality in DNA Testing
- 06 Understanding a Forensic DNA Lab Report
- 07 Statistics and Population Genetics
- 08 Mitochondrial DNA & Y-STR Analysis
- 09 Forensic DNA Databases
- 10 Collection of DNA Evidence from Suspects and Arrestees
- 11 Pretrial DNA Evidence Issues
- 12 Victim Issues
- 13 Trial Presentation
- 14 Postconviction DNA Cases
- 15 Emerging Trends
Principles of Forensic DNA
for Officers of the Court
for Officers of the Court
Module 2 :: Biology of DNA
Topic 1 :: Biological Terminology
The Double Helix
The structure of DNA is like a ladder with the base pairs forming the rungs of the ladder. The entire ladder is twisted upon itself like a spiral staircase to form the double helix.
Forensic scientists look at many specific regions on the DNA double helix. Each of those regions has several base pairs (rungs), but no two humans, except identical twins, have the same combination of base pairs at all of the regions. Identical twins can not be differentiated based on regions currently tested by forensic scientists.
Click here to learn more about base pairs and the DNA double helix.
