Units of inheritance in pairs, dominance and recessiveness, equal segregation, independent assortment. These ideas weren't recognized for 34 years.
Experiments from 1866 are rediscovered and confirmed by three separate researchers one Dutch, one German, and one Austrian. William Bateson soon translates Mendel's paper into English.
The chromosome theory of heredity is confirmed in studies of fly eye color inheritance
H. Muller shows that X-rays induce mutations in a dose-dependent fashion.
Some component of heat-killed virulent bacteria can "transform" a non-virulent strain to become virulent, as shown by Fred Griffith. This sets the stage for work done in 1944.
In DNA, there are equal amounts of A and T, and equal amounts of C and G, but the A+T to C+G ratio can differ between organisms.
The genetic code is cracked by a number of researchers using RNA homopolymer and heteropolymer experiments as well as RNA labeling experiments.
PCR is developed by Kary Mullis
Automated sequencing technology allows genome projects to accelerate
Controversies continue over human and animal cloning, research on stem cells, and genetic modification of crops.