Skip Navigation
The Endowment for Human Development
The Endowment for Human Development
Improving lifelong health one pregnancy at a time.
Donate Now Get Free Videos

Movie Theater

DNA


From The Biology of Prenatal Development.Buy Now

Script: The zygote's 46 chromosomes represent the unique first edition of a new individual's complete genetic blueprint. This master plan resides in tightly coiled molecules called DNA. They contain the instructions for the development of the entire body.

DNA molecules resemble a twisted ladder known as a double helix. The rungs of the ladder are made up of paired molecules, or bases, called guanine, cytosine, adenine, and thymine.

Guanine pairs only with cytosine, and adenine with thymine.

All ages referenced to fertilization, not last menstrual period.
See Snapshots   |   Log in to create a playlist
Firm Hand Grasp
Firm Hand Grasp
Ready for Birth
Ready for Birth
DNA
DNA
To the Earth and Back
To the Earth and Back
Fertilization 1
Fertilization 1
Fertilization 2
Fertilization 2
Free resources and training for educators
Buy the Biology of Prenatal Development DVD