Bacteriophages and Their Mechanisms

Bacteriophages, or phages, are viruses that infect bacteria, particularly Escherichia coli. They have a double-stranded DNA structure with a head and tail. Phages attach to bacterial walls, inject their DNA, and can follow two reproductive cycles: lysogenic and lytic. In the lysogenic cycle, viral DNA integrates into the bacterial chromosome, replicating with it. The lytic cycle begins when external factors disrupt the lysogenic state, leading to the production of new phages and the destruction of the bacterial cell through lysis.

What type of organisms do bacteriophages infect?

• Fungi

• Plants

• Animals

• Bacteria

Which bacterium is commonly infected by bacteriophages studied in research?

• Escherichia coli

• Pseudomonas aeruginosa

• Bacillus subtilis

• Staphylococcus aureus

What is the genetic material of bacteriophage T4?

• Double-stranded DNA

• Double-stranded RNA

• Single-stranded DNA

• Single-stranded RNA

Where is the nucleic acid of bacteriophage T4 located?

• In the tail

• In the tail fibers

• In the capsid

• In the base plate

How does a bacteriophage attach to a bacterial cell?

• Through its tail fibers

• Through its tail

• Through its head

• Through its base plate

What is the initial step in the lysogenic cycle?

• Replication of viral DNA

• Integration of viral DNA into the bacterial chromosome

• Destruction of the bacterial cell

• Production of new viral particles

What is the viral DNA called when it is integrated into the bacterial chromosome?

• Prophage

• Capsid

• Lysogen

• Virion

What triggers the transition from the lysogenic to the lytic cycle?

• Replication of bacterial DNA

• External factors

• Integration of viral DNA

• Production of viral proteins

What happens to the bacterial cell at the end of the lytic cycle?

• It is destroyed

• It integrates viral DNA

• It becomes a lysogen

• It continues to reproduce normally