Image: Giant liposomes composed of the natural fats and proteins lining the mammals' alveoli at the surface of the lungs. Image acquired with a fluorescence single- and two-photon laser scanning confocal microscopy.
Considered the blueprint of life, DNA is found in all living cells. Scientists think it was preceded by RNA, which may have played a role in the development of the first life on Earth. Image Credit: Illustration by Dr. Frank Cucinotta, NASA/Johnson Space Center, and Prem Saganti, Lockheed Martin