AQA biology 16.2 Antibiotics

Question	Answer
what is the word antibiotic derived from?	Greek words meaning against life
what do antibiotics do?	destroy or inhibit the growth of micro-organisms
what are most produced by?	Bacteria
what is penicillin made by	fungi
who discovered penicillin?	Alexander Fleming, 1928
how do they work in basic terms?	stop bacteria from making normal cell walls
how do bacteria cells resist osmosis?	has a cell wall made of inelastic, tough material.as water enters, contents expand and push against cell wall. this halts further entry of water
what does this prevent?	osmotic lysis
how do some antibiotics kill bacteria?	prevent the cell wall forming.
how do they do this?	inhibit synthesis and assembly of important peptide cross-linkages in walls.
what does this mean for the walls?	they're weakened and experience lysis, killing the bacterium
when is this type of antibiotic useful?	when the bacteria is growing
why aren't viruses killed by antibiotics?	they have a different covering from bacteria
what is resistance due to?	not a change in tolerance but a mutation within the bacteria
what was the mutation that allowed them to t=resist?	they produced a new protein. an enzyme which broke down antibiotic penicillin before it could kill the bacteria.
what was the name given to this enzyme?	penicillinase
how is the production of penicillinase passed on?	vertical gene transmission
what eventually happens?	this becomes predominant in the population as the frequency for the allele to form penicillinase increases in the population
how can this resistance be transferred to other bacterial species?	horizontal gene transmission
what can this lead to?	certain bacteria accumulating DNA that gives them resistance to a range of antibiotics
what is the name give to these bacteria?	super-bugs

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AQA biology 16.2 Antibiotics

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	Created by Charlotte Hewson about 9 years ago