If a person with a bacterial infection does not complete the prescribed course of an antibiotic, this creates conditions that allow the bacterial population to become resistant to the antibiotic. A mutation in a bacterial gene may confer resistance to an antibiotic. Directional selection can occur when the antibiotic is present in the environment. A bacterium may also acquire resistance if it obtains genetic material from another bacterium by a process called horizontal gene transfer. Outline how directional selection and horizontal gene transfer produce a new bacterial population that is resistant to an antibiotic.
Some bacterial infections can be treated only with one antibiotic because the pathogens are resistant to all the others. A drug is being developed to improve treatment. • The drug is a short polynucleotide. • The drug blocks translation of the messenger RNA (mRNA) made when the gene linked to antibiotic resistance is transcribed. • The bacteria then become susceptible to more antibiotics. Suggest and explain how the drug could make bacteria susceptible to more antibiotics.
Outline how natural selection is different from selective breeding.
Explain why farmers need to buy new seeds every year.