Govt. Exams
Entrance Exams
The F (fertility) plasmid encodes the sex pilus (F pilus) that forms a bridge between F+ and F- cells for DNA transfer. This is bacterial conjugation, a horizontal gene transfer mechanism.
Enveloped viruses acquire their envelope from host cell membranes (plasma membrane, nuclear envelope, or ER) during viral release. The envelope contains both host and viral proteins.
Penicillin inhibits peptidoglycan cross-linking in bacterial cell walls. Streptomycin targets ribosomes, tetracycline inhibits protein synthesis, and chloramphenicol inhibits 70S ribosomes.
Flagella enable bacterial movement in response to chemical gradients (chemotaxis). Chemoreceptors detect signals, but flagella provide the locomotion. The other options are not functions of flagella.
Viruses lack their own metabolic machinery and depend on host cell machinery for replication. Options A, C, and D are all characteristics of viruses.
Influenza viruses (types A, B, and C) belong to the family Orthomyxoviridae. They are enveloped, negative-sense RNA viruses with segmented genomes.
Bacteriophages replicate through either the lytic cycle (destroying the host cell) or lysogenic cycle (integrating DNA into host chromosome). Binary fission is bacterial reproduction.
