Antibiotic Resistance

Question 1

what are antibiotics?

Answer 1

chemicals that kill bacteria and do not usually harm animal cells - they achieve this by targeting cell structures such as bacterial cell walls, which animal cells do not contain

Question 2

why do humans develop antibiotic resistance?

Answer 2

this is due to natural selection occurring in response to the overuse of antibiotics, in particular the first antibiotic, penicillin

Question 3

how did humans develop antibiotic resistance?

Answer 3

1. originally, none of the bacteria were resistant and penicillin was not used
2. doctors began to use penicillin, which killed the bacteria
3. a chance mutation gave some bacteria resistance to the antibiotic
4. these bacteria were better adapted to an environment in which penicillin was used
5. they survived in greater numbers - as there are fewer non-resistant bacteria there is less competition for resources
6. so the resistant bacteria reproduce rapidly and passed on the resistance allele
7. this was repeated with each generation of bacteria
8. the proportion of bacteria with the resistance allele increased until most had the allele