modes of action Flashcards
Protein synthesis steps?
initiation: 1st tRNA brought to AUG start codon on the mRNA molecule . 30s subunit attaches to mRNA, and 50s subunit comes in place.
Elongation: 2nd tRNA molecule enters the A (acceptor site). amino acid detaches from first tRNA, peptide bond is formed between 1st and 2nd amino acids. Ribosomes moves along..
Termination: ribosome reaches stop codon, specific proteins cause ribosomal subunits to separate and peptide chain to be released.
NAME DRUGS THAT ARE INHIBITOR OF PROTEIN SYNTHESIS
TERTRACYCLINES i.e doxycycline (attacks 30s subunit AMINOGLYCOSIDES, i.e gentamicin (attacks 30s subunit) Chloromaphenicol OXAZOLIDINONES Macrolides Streptogramin Lincosamides Fusidic acid
How do tetracyclines i.e doxycycline inhibit protein synthesis?
Binds reversibly to the A site on 16s rRNA in 30s subunit
Inhibits binding of tRNA to A site, which inhibits protein synthesis.
Binding reversible, effects bacteriostatic
how do aminoglycosides i.e gentamicin inhibit protein synthesis
Bind irreversibly to the A site on the 16s rRNA in 30s subunit
they inhibit binding of the tRNA to A site
ptrvent formation of the initiation complex, cause misreading of the codons along the mRNA and they cause an increase in membrane permeability. Binding irreversible, effects bactericidal
What is the process of DNA replication
dsDNA is unwound by helicase to expose template DNA strands. Unwinding generates supercoils which is removed by DNA gyrase (Topoisomerase ii) Zone of unwound DNA is called replication fork. DNA polymerase synthesis complimentary DNA strands at replication fork. Replication is bidirectional.
What are the drugs that inhibit DNA replication
Fluoroquinolone’s i.e. ciprofloxacin, levofloxacin
How do FLUOROQUNIOLONE’S inhibit DNA replication ?
They bind to DNA gyrase and Topoisomerase IV,
DNA gyrase removes DNA supercoils ahead of replication fork (before replication)
Topoisomerase IV separates DNA after replication
This inhibits DNA replication and packaging of DNA within the bacteria cell which leads to bacterial cell lysis.
What antibiotics are examples of B Lactams ?
Penicillin’s, Cephalosporins, Carbapenems
Which antibiotics act on cell wall synthesis?
B lactams and Glycopeptides (Vancomycin, Teicoplanin)
How do B lactams inhibit cell wall synthesis
Binds to the enzyme that cross link peptidoglycans. the enzyme are transpeptidase which leads to cell lysis
They also get incorporated into peptide chain to prevent x linking
How do Glycopeptides prevent cell wall synthesis?
Prevents Glycosylase enzyme from adding Peptidoglycan monomer on to the PG chain which prevents X linking.
What antibiotics act on cell membrane?
Polymixins (Colistin) Lipopetides (daptomycin, CUBICIN)
How do polymixins inhibit cell membrane synthesis
They only act on gram negative bacteria, they disrupt the membrane and cause leakage of cytoplasmic contents
what antibiotics act on RNA polymerase
Rifamycins i.e rifampicin
which antibiotics affect DNA?
Nitroimidazoles i.e metronidazole
