Question

Which of the following phases requires lysozyme for the lytic cycle of viruses?
(a) Eclipse phase
(b) Latent phase
(c) Penetration phase
(d) Absorption phase

Answer 1

Hint: An enzyme that is present generally in the saliva and tears of humans and animals that break the cell wall of the bacteria which leads to its death. It is located in the tail region and infects the cell when it is injected.

Complete answer:
The lytic cycle is the cycle related to the reproduction of the virus that includes the bacteriophages. The enzyme lysozyme is present in the tail region of the bacteriophage which causes infection in the viruses when they penetrate inside them and degrades the cell wall leading to cell death.
- The reproduction cycle of viruses involves two cycles: the lytic cycle and the lysogenic cycle.
- The lytic cycle results in the destruction of the cell and its membrane when infected.
- The lytic cycle is also called the virulent phase as it has the ability to infect the host cells.
- In the lytic cycle, the DNA of the virus remains free inside the bacterial cell where its replication occurs from the host bacterial DNA.
- The lytic cycle involves six phases or stages, they are attachment, penetration, transcription, biosynthesis, maturation, and lysis.
- The penetration phase is the phase where the phage infects the host cell and when the phage enters the host cell then the lysozyme present in its tail region will also enter inside it and then destroys its cell wall.
- The lysozyme infects the host bacterial cell during the penetration phase where it injects the tail region inside the host cell and destroys a portion of the cell wall.
- The lysogenic cycle is different from the lytic cycle as in this cycle the DNA of the virus is present inside the host bacterial DNA.

So, the correct answer is the ‘Penetration phase’.

Note: Professor George W. Kenner and his colleagues were the first to attempt for the synthesis lysozyme enzyme chemically at the University of Liverpool, England. Later the synthesis of lysozyme was achieved at Steve Kent’s lab at the University of Chicago in 2007 by Thomas Durek. Alexander Fleming in 1922 as the first to observe the bacteria- killing activity of the lysozyme enzyme.