Mutations and antibiotic resistance

• what is mutation?

  • changes to the genetic code
• how does mutation take place within an organism (step 1)?

  • sometimes a gene mutates - mutation is rare - random change in an organism's DNA can be inherited
• how does mutation take place within an organism (step 2)?

  • Mutation - change sequence of DNA bases in gene - produce genetic variant
  • sequence of DNA bases code for sequence of amino acids - make up a protein
  • mutation to a gene sometimes leads to change that protein codes for
  • Enzymes have specific active site - Mutation can change change shape of active site - altering function or stop production of enzyme altogether
• how does mutation take place within an organism (step 3)?

  • Most mutations have no effect on phenotype - neutral - e.g. mutation occurs in unimportant region of DNA - mutated codon still codes for same amino acid - protein structure + function unaffected - no effect if recessive allele
  • some mutation have small effect of phenotype - change in amino acid only has slight affect on protein structure + function - individual characteristic altered very slightly
  • very rarely mutation has significant effect on phenotype - e.g. may result in very different protein - no longer carries its function - mutation can be harmful or beneficial
• how does mutation take place within an organism (step 4)?

  • chance of mutation increased by
  • ionising radiation - x-rays, gamma rays
  • chemicals called mutagens - chemical and tobacco
• how can bacteria evolve to be antibiotic resistant?

  • Bacteria develops random mutations in their DNA - lead to changes in bacteria characteristics
  • bacteria less affected by particular antibiotic
  • bacteria - large advantage to resist antibiotic - for survival - lives for longer to reproduce many times
  • leads to allele for resistance to be passed on to lots of offspring - natural selection - spreads and more common in population of bacteria overtime
  • problem for people who are infected with this is you can't easily get rid of them with antibiotics