PED2006 EXAM PRACTICE Flashcards
(274 cards)
What is bacterial conjugation
genetic transfer between bacteria that involves direct cell-to-cell contact
how does antibiotic resistance spread
transfer of genetic material through bacterial conjugation
what are the four steps in the conjugation process
formation of pilus
mating pair formation
transfer of plasmid DNA
separation
what happens during the formation of pilus
the donor bacterium, which contains a conjugative plasmid, extends a hair like appendage called a pilus
the pilus attaches to the surface of the recipient bacterium, forming a connection between the two cells
what happens during mating pair formation
the pilus retracts, bringing the two bacteria into close contact
a mating bridge forms between the cells, allowing the transfer of genetic material
what happens during the transfer of plasmid DNA
the conjugative plasmid in the donor cells is nicked at a specific site called the origin of transfer
one strand of the plasmid DNA is transferred to the recipient cell through the mating bridge
the single stranded DNA in both the donor and recipient cells is replicated to form double stranded plasmids
what happens during separation
after the transfer is complex, the mating bridge dissassembles, and the two bacteria separation
both the donor and recipient cells now contain the plasmid
what is required for antimicrobial resistance spread
presence of resistance genes
horizontal gene transfer
proliferation of resistance bacteria
what is horizontal gene transfer
conjugations allows for the horizontal transfer of R plasmids between bacteria, which can occur when between different species
this means that a non-resistant bacterium can quickly acquire resistance genes from a resistant donor
how does proliferation of resistant bacteria occur
once a bacterium acquire a resistance plasmid, it can survive and proliferate in the presence of antibiotics
these bacteria can further transfer the plasmid to other bacteria, spreading the resistance genes within and between bacterial populations
what are the clinical implications of the spread of antimicrobial resistance
the spread to antibiotic resistance genes through conjugations can lead to the emergence of multi-drug resistant bacterial strain
this poses a significant challenge for treating bacterial infections, as standard antibiotics become ineffective, necessitating the use of more potent and often more toxic alternatives
what are fluoroquinolone
a class of broad-spectrum antibiotics that are effective against a variety of gram positive and gram negative bacteria. they exert their antibacterial effects by targeting bacterial DNA replication and transcription
what is the mechanism of actions of fluoroquinolone
inhibitions of DNA gyrase
inhibition of topoisomerase 4
what is the functions of DNA gyrase
in bacteria, DNA gyrase is an essential enzyme that introduces negative supercoils into DNA. this is critical for the replication and transcription processes as it prevents the DNA helix from becoming overall tangles and allows it to unwind
what is the action of fluoroquinolone
bind to the DNA gyrase-DNA complex, stabilising the enzyme-DNA interaction. this prevents the enzymes from resealing the DNA double strands after they have been cut to relieve the torsional strain
why is the inhibition of DNA gyrase important
the interruption of this process leads to the accumulation of double stranded DNA breaks, which ultimately results in bacterial cell death
what is the function of topoisomerase 4
this enzyme is involved in the separation of interlinked daughter DNA molecules following DNA replication. it is crucial for proper cell division
how do fluoroquinolone impact toposimerase 4
fluoroquinolone interferes with the activity of topoisomerase 4 by stabilising the cleavage complex that the enzyme forms with DNA
why is inhibition of topoisomerase 4 beneficial
this action prevents the segregation of replicated chromosomal DNA into daughter cells, thereby inhibition of bacterial cell division and leading to cell death
what are the benefits of fluoroquinolone
broad spectrum so effective against a wide range of bacteria
bactericidal effect - they kill bacteria due to irreversible damage they cause to bacterial DNA
drawback of fluoroquinolone
resistant mutations can develop in the genes encoding DNA gyrase and toposimerase 4, which are prevent in various bacterial species
what is the posterior lobe of the pituitary gland
the posterior lobe of the pituitary gland plays a crucial role in the regulation of various physiological processes
what is the location of the posterior lobe
the posterior lobes is located at the base of the brain, attached to the hypothalamus by the pituitary stalk
what is the hypothalamic hypophyseal tract
the axons of neurone from the supraoptic and paraventricular nuclei of the hypothalamus extend down through the pituitary stalk into the posterior lobe. these neuron’s synthesise hormone and transport them along their axons to be stored and released from the posterior pituitary