3.1 How do mutations lead to resistance?

A bacterium can develop antibiotic resistance through genetic mutations that are permanent changes in the deoxyribonucleic acid (DNA) sequence that makes up a gene. Perhaps the best example of acquisition of resistance by mutation is Mycobacterium tuberculosis, where resistance to all therapeutic agents is caused by mutation.

How does altering the sequence of a bacterium’s DNA result in antibiotic resistance? The answer lies in how genetic information, encoded by DNA, is converted into proteins that are required for the structure and function of bacteria.

Optional activity: What do genes do?

If you are unfamiliar with the terms ‘DNA’, ‘RNA’, ‘base pair’, ‘gene’, ‘amino acid’ or ‘protein’, you may want to try our free OpenLearn course What do genes do? [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] before you begin the following sections.

3 Why are so many bacteria resistant to antibiotics?

3.1.1 From genetic information to protein function