Compare and contrast the lytic and lysogenic reproductive cycles of viruses. ?

Question

Compare and contrast the lytic and lysogenic reproductive cycles of viruses. Give at least 2 ways they are alike and 2 ways they are different.

Answer 1

Lytic Cycle

1. Attachment: The virus binds to specific receptors on the host cell.

2. Entry:

There are two ways in which a virus can enter cells. Firstly, the virus can inject its nucleic acid into the host cell. Secondly, if a virus is contained in an envelope, the host cell can phagocytosise the entire virus particle into a vacuole. When the virus breaks out of the vacuole, it then releases its nuclear acid into the cell.

3. Replication: The virus's nucleic acid instructs the host cell to replicate the virus's DNA or RNA.

4. Assembly: New virus particles are assembled.

5. Lysis & Release: The virus directs the production of an enzyme which damages the host cell wall, causing the host cell to swell and burst. The newly formed virus particles are now released.

Lysogenic Cycle

1. Similar to Lytic Cycle

2. Similar to Lytic Cycle

3. Incorporation: The viral nucleic acids is not replicated, but instead integrated by genetic combination (crossing over) into the host cell's chromosome. When integrated in a host cell this way, the viral nucleic acid as part of the host cell's chromosome is known as a prophage.

4. Host Cell Reproduction: The host cell reproduces normally. Subsequent cell divisions, daughter cells, contain original father cell's chromosome embedded with a prophage.

5. Cycle Induction: Certain factors now determine whether the daughter cell undergoes the lytic or lysogenic cycle. At any time, a cell undergoing the lysogenic cycle can switch to the lytic cycle.

The reproduction cycle of viruses with RNA and no DNA is slightly different. A notable example of a RNA-based virus is HIV, a retrovirus