Asked by: Lizzie Barker, Leamington Spa
There isn’t a single gene for photosynthesis, which is the process plants use to produce glucose from the Sun’s energy. Plants can photosynthesise because their cells contain chloroplasts, which were originally free-living bacteria that entered into a symbiotic relationship with single-celled organisms about 1.5 billion years ago. Chloroplasts have their own DNA and reproduce inside plant cells, but they also need the plant to provide the right environment.
In 2010, Harvard researchers tried injecting photosynthetic bacteria into the eggs of zebrafish. They found that the bacteria were still alive two weeks after the fish hatched. But the bacteria didn’t grow or reproduce and they didn’t generate much sugar.
Some animals in nature have partially harnessed photosynthesis. For example, reef-building corals and giant clams contain photosynthetic algae. But photosynthesis only creates sugar. Plants can make all the other biochemical molecules they need, but animals must absorb additional nutrients from food, so photosynthesis could never be a complete replacement for eating.