The Lilac Story 2
Half of the DNA in the nucleus came from its mother and half was received from its father. Pollen delivered the father’s DNA when it fertilized the egg of the mother parent. The inheritance of DNA within the nucleus is called nuclear inheritance, and the inheritance of genes can be followed in a predictable manner since each parent contributes half of the DNA (Figure 2).
Our breeders were also familiar with plant cells. Just like every cell in a plant contains DNA, every cell also has organelles (Fig. 3).
Organelles are structures in a cell that are specialized to perform certain functions for the cell.
Figure 2. The inheritance of nuclear DNA follows a predictable pattern that is universal across species. The mother and the father will both donate half of their genes, whether it is big A or little a, and the resulting offspring depicted inside the box will have 50% of its genes from the father and 50% from the mother. Image from passel2.unl.edu.
Fig. 3: A simplified plant cell showing the nucleus and organelles. Most DNA is found in the nucleus, but some can be found in the chloroplasts and mitochondria. Image designed by Ransom Sitz.
Chloroplasts are organelles that give plants their green color and are also where photosynthesis takes place.
Photosynthesis is the process of converting light energy into chemical energy (in the form of sugars).
Another organelle, mitochondria, breaks the bonds in the sugar molecules to release energy, which is then used to power other reactions in the cell.
Mitochondria are considered the power station of cells, using fuel created by the chloroplasts.
Due to a quirk of evolutionary history, both the chloroplasts and mitochondria carry inside of them DNA that is independent of the DNA in the cell nucleus. This organelle DNA instructs the organelle on form and function.