How do you grow cells, or do they grow on there own? and how do you make them express their protein/product?

Question: How do you grow cells, or do they grow on there own? and how do you make them express their protein/product?
- Keywords:
  cell,
  express,
  grow,
  protein
Asked by Mestres690 to Sian on 8 Mar 2018.
- Sian Richardson answered on 8 Mar 2018:
  
  I grow E.coli which is a bacteria which you can find in your intestines. They will grow on their own however we have genetically modified our E.coli therefore it will only grow under certain conditions we have given it. Our product which is a protein is expressed by the E.coli. We do this by inserting a loop of DNA (called a plasmid) into the cells which contains a copy of our product. When the cells divide they copy this loop of DNA as well (transcription) and we can then induce the expression of our protein (translation). Cells are just like people they need food, air and warmth, so we keep them happy by controlling all these things.

Question: How do you grow cells, or do they grow on there own? and how do you make them express their protein/product?