5.14 understand that large amounts of human insulin can be manufactured from genetically modified bacteria that are grown in a fermenter

The gene that causes human insulin production is taken from a cell and put into a bacteria's DNA. This bacteria is then put into a fermenter where the conditions are optimum for it to replicate many times. These bacteria then produce human insulin which can be harvested and given to humans with diabetes.

This is a very helpful animation:
http://www.abpischools.org.uk/page/modules/diabetes/diabetes6.cfm?coSiteNavigation_allTopic=1