Chromosome Inhibitors Flashcards
How many copies of each chromosome do prokaryotes have?
Single copy = Haploid
Which organism has a smaller genome size?
Prokaryotes
What does a prokaryotes chromosome have?
A circular dsDNA localised within a Nucleoid
What is the difference in DNA replication between the 2 cell types?
Different enzymes
Function of DNA Helicase
Topoisomerase I - unwinds the supercoiled DNA double helix + separates 2 template DNA strands
What holds the DNA strands apart when forming replication fork?
Single stranded binding proteins
Function of Primase
Synthesizes a short RNA molecule complementary to template DNA
Types of Topoisomerase enzymes
TYPE 1 - cut + rejoin one strand of DNA (Topoisomerase I + III)
TYPE 2 - cut + rejoin both strands of DNA (Topoisomerase IV + DNA T.II gyrase )
Fluroquinolones
Inhibit topoisomerase not found in mammalian cells
- Broad-spectrum + Bactericidal against gram-negative & gram-positive such a P.aeruginosa
- Ciprofloxacin is a good oral anti-pseudomonas drug available
- useful if patient can’t take B-lactams
- High risk C.difficile infection linked to MRSA colonisation
What does Fluroquinolones target?
Chromosome
Fluroquinolones used to treat
UTI
GI
Genital
Respiratory tract infections
What is the target of Fluroquinolones in gram negative
Topoisomerase 2 = DNA gyrase
- by producing + removing super oils
What is Fluroquinolones target in gram positive
Topoisomerase 4
- removes links + knots made behind replication fork
Transcription steps
Initiation
Elongation of RNA transcript
Termination
Rifampicin mode of action
Act on B subunit of RNA polymerase inhibiting RNA transcription
- rifampicin resembles 2 adenosine nucleotides in RNA forming basis to B subunit
- Bactericidal
What antibiotics act on chromosome
Rifampicin
Fluoroquinolones
Nitroimidazole/nitrofurans (metronidazole)
Which drug is second line for UTI
Nitrofurantoin
Metronidazole mode of action
Nitroimidazole (also nitrofurantoin
- Broad spectrum
- Prodrug = active after nitro group os reduced in low redox environments
- Reduction is non-enzymatic
- metabolites are unstable + react with DNA causing irreversible damage
alternative to amoxicillin for severe mouth infection
Nitroimidazole
Break DNA strand chemically
