Antibiotics Flashcards
How can antibiotics inhibit bacterial transcription? How do cells become resistant?
The antibiotic blocks the action of RNA polymerase and so RNA cannot be made. Cells can become resistant by a change in shape so that the drug no longer inhibits.
When an antibiotic binds to an active site on a ribosome what is it inhibiting?
This is inhibiting protein synthesis because RNA cannot bind to its codon.
State two ways in which bacteria can become resistant to antibiotics which inhibit protein synthesis.
They can create a new pump which pumps the drug out of the cell, or their ribosomal protection proteins stop the drug binding to the ribosome.
What is the action of antifolates in chemotherapy?
These have a similar shape to the coenzyme folic acid and so inhibit this reaction (competitively). This leads to decreased DNA and RNA synthesis which prevents replication.
Can cells become resistant to antifolates?
Yes. They do this by either lack of retention in cell or reduced uptake of the drug. They can also produce enzymes which produce folic acid.
How is bacterial resistance passed on?
This can be passed on either horizontally (transduction, transformation or conjugation) or vertically (mitotic cell division).
What is transduction?
This is where bacteria are transferred DNA by bacteriophages.
What is transformation in relation to bacteria?
This is where bacteria pick up DNA from the environment.
What is the structure which DNA passes through during conjugation?
Pilli.
Explain how antibiotics can inhibit cell wall synthesis. How can cells become resistant?
They can bind to the end of peptidoglycan chains to prevent incorporation of them into the cell wall. Changes at the terminus can mean that the drug cannot bind and the bacteria has become resistant.
