Figure: Natural selection in 3 stages — variation, selection, then a fully resistant population.
The Process of Natural Selection:
- Genetic Variation: Random mutations in bacterial DNA create variation in populations
- Selection Pressure: When antibiotics are used, they create environmental pressure
- Survival of the Fittest: Bacteria with resistance mutations survive while others die
- Reproduction: Resistant bacteria multiply and pass resistance genes to offspring
- Population Change: Over time, resistant bacteria become dominant in the population
Mechanisms of Resistance:
- Enzyme Production: Bacteria produce enzymes that break down antibiotics
- Target Modification: Changes to bacterial structures that antibiotics normally target
- Efflux Pumps: Bacteria pump antibiotics out of their cells
- Alternative Pathways: Bacteria develop new metabolic routes to bypass disrupted processes
This deep dive covers How Antibiotic Resistance Develops within Antibiotics and Drug Resistance for GCSE Biology. Antibiotic function, bacterial resistance evolution, responsible use, global health impact It is section 5 of 18 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for Antibiotics and Drug Resistance
What do antibiotics kill or stop growing?
Explain how antibiotic resistance develops in bacteria through natural selection. (3 marks)
Quick recall flashcards
Why do antibiotics NOT work against viruses?
Antibiotics target bacterial cell walls and bacterial processes.
Viruses do not have cell walls and use the host cell's own machinery to reproduce.
There is nothing for the antibiotic to target in a virus.
What are antibiotics and what do they target?
Antibiotics are chemicals that kill bacteria or stop them from growing.
They target structures that bacteria have but human cells do not, such as cell walls.
Examples: penicillin, amoxicillin, streptomycin.