Which extrachromosomal genetic element carries drug and disease resistance genes in bacteria?
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Answer: B. Plasmid
Explanation
Plasmids are small circular DNA molecules existing separately from the bacterial chromosome inside the cytoplasm. They frequently harbor specialized genes that provide bacteria with resistance against various environmental antibiotics and diseases. Bacterial cells can easily transfer these mobile genetic elements horizontally to rapidly spread resistance traits among populations. Extrachromosomal genetic elements replicate independently of the primary bacterial chromosome during standard cellular division cycles. Antibiotic resistance genes allow bacterial strains to survive lethal pharmacological treatments designed to eliminate pathogenic infections. Bacterial conjugation enables direct transfer of plasmid DNA between neighboring microbial cells in diverse natural environments.
Nucleotides are the basic monomer building blocks that compose nucleic acids rather than being extrachromosomal genetic elements. Mesosomes are plasma membrane infoldings in bacteria that artifactually appeared during preparation for electron microscopy studies. Ribosomes are ribonucleoprotein complexes responsible for cellular protein synthesis and do not carry hereditary disease resistance genes.
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