An introduction to why we do GM of crops (not really how). Lots more resources from the Royal Society on GM can be found here
A very surficial look at the very new method called CRISPR - pay attention to this tech as you are going to see it pop up more and more when it comes to genetically modifying food (and other things!). Here is just one example article (I bet you can find tons!)
“Some segments of people aren’t going to care as much about how it was done...as long as they get this amazing thing they get to eat.”
Heirloom
Open Pollinated
Separating Pollination by time, distance, or genetics
Landrace
Hybrid
Organic
GMO
selective breeding (not often considered GMO)
transgenic
CRISPR
Image #1 - general process
Image #2 - process applied to maize - second year hybrid
The first stage in making a GM plant requires transfer of DNA into a plant cell. One of the methods used to transfer DNA is to coat the surface of small metal particles with the relevant DNA fragment, and bombard the particles into the plant cells. Another method is to use a bacterium or virus. There are many viruses and bacteria that transfer their DNA into a host cell as a normal part of their life cycle. For GM plants, the bacterium most frequently used is called Agrobacterium tumefaciens. The gene of interest is transferred into the bacterium and the bacterial cells then transfer the new DNA to the genome of the plant cells. The plant cells that have successfully taken up the DNA are then grown to create a new plant. This is possible because individual plant cells have an impressive capacity to generate entire plants. On rare occasions, the process of DNA transfer can happen without deliberate human intervention. For example the sweet potato contains DNA sequences that were transferred thousands of years ago, from Agrobacterium bacteria into the sweet potato genome.