Taking examples under each category, discuss upstream and downstream processing
Upstream processing: This involves identifying a material, which can be transformed for making the final product. Let us take the example of making BT cotton. In this, extracting the gene for insecticide toxin from B. thuringiensis is an example of upstream processing. Similarly, introducing this gene into cotton is an upstream process.
Downstream processing: This involves suitable purification and isolation of the final product. Let us take that example of fermentation to understand this. Purification of alcohol through distillation is part of downstream processing.