AnTibiotics 2 Flashcards
What is conjugation
Conjugation is process by which one bacterium transfers genetic material to another through direct contact.
What is vertical evolution
Vertical evolution is passing on of allele from 1 generation to the next
What is horizontal evolution
Horizontal evolution is when a plasmid carrying gene for antibiotic resistance is made and 1 strand of double stranded plasmid DNA transfers between conjugating bacteria. Each bacteria replicates strand to make complete plasmid
Why do bacteria become resistant to antibiotics
Bacteria become resistant to antibiotics because mutations with bacterial DNA could result in an allele that makes bacteria resistant to method of action by an antibiotic. This creates variation
These bacteria likelier to survive in antibiotic (selection pressure)
Bacteria that are susceptible die, resistant survive
Surviving Bacteria reproduce by mitosis and pass on allele for antibiotic resistance. Bacteria can transfer antibiotic resistance to other bacteria
Overtime allele accumulates in bacterial population
What are causes of antibiotic resistance
Causes of antibiotic resistance are
Overprescribing of antibiotics (more bacteria become resistant)
Patients not finishing treatment (may not kill all bacteria, some resistant may remain)
Poor infection control in hospitals and care homes (if bacteria is resistant and may spread throughout hospitals)
Why can bacteria evolve swiftly
Bacteria can evolve swiftly because bacteria reproduce very quickly
More opportunities for mutations, may result in antibiotic resistance
Able to re establish population size very quickly
Bacterial population are usually in billions, so number of cells containing mutation is vast
What mutations can make bacteria resistant to antibiotics
Mutations that can make bacteria resistant to antibiotics include:
Mutation to allow enzyme to break down antibiotic
Mutation allowing bacteria to use different metabolic pathway for reactions inhibited by antibiotic
How does bacterial conjugation/horizontal evolution work
Bacterial conjugation works when a conjugation tube forms between donor and recipient, an enzyme makes a nick in plasmid. Plasmid DNA replicates and the free DNA strand starts moving through tube. In recipient cell, replication starts on transferred DNA. Cells move apart and plasmids form circle.
