A. An illness caused by a virus causes fever, rashes and joint pain. Symptoms quickly occur within 3-5 days. What is the reproductive cycle of this virus?
B. What are major differences between the lytic and the lysogenic cycles?
A. The reproductive cycle of this virus is likely the lytic cycle, as it causes rapid symptoms within a short period of time (3-5 days).
B. Major differences between the lytic and lysogenic cycles include:
1. Lytic Cycle:
- The viral DNA enters the host cell and immediately takes control of the cellular machinery.
- The viral DNA directs host cell to produce new viral components, such as viral proteins and genetic material.
- These components assemble to form new viruses.
- The host cell lyses (bursts), releasing the newly formed viruses to infect other cells.
- The lytic cycle results in immediate cell death and the virus spreads quickly.
2. Lysogenic Cycle:
- The viral DNA integrates into the host cell's DNA, becoming a part of the host genome.
- The viral DNA is replicated along with the host cell's DNA during cell division.
- The viral DNA remains in a dormant state, not producing new viral particles.
- In certain conditions or due to environmental triggers, the viral DNA can be activated to undergo the lytic cycle.
- The lysogenic cycle allows the virus to persist within the host cell for long periods without causing immediate cell death.
A. The reproductive cycle of a virus refers to the series of steps it takes to reproduce and infect new host cells. In the case of the virus causing fever, rashes, and joint pain, the reproductive cycle can be described as follows:
1. Attachment: The virus attaches itself to specific receptors on the surface of host cells.
2. Penetration: The virus injects its genetic material, which can be either DNA or RNA, into the host cell.
3. Replication: The viral genetic material takes control of the host cell's machinery and hijacks it to produce viral components, such as proteins and new genetic material.
4. Assembly: The viral components are assembled to form new virus particles.
5. Release: The newly formed virus particles are released from the infected host cell, often causing the death of the host cell in the process.
6. Spread and Infection: The released virus particles can then infect new host cells, starting the cycle again.
B. The major differences between the lytic and lysogenic cycles are as follows:
Lytic Cycle:
1. The lytic cycle is characterized by the immediate reproduction of the virus, leading to the death of the infected host cell.
2. The viral genetic material takes control of the host cell's machinery, commanding it to produce viral components.
3. The viral components are assembled, resulting in the formation of new virus particles.
4. The host cell undergoes lysis, where it is ruptured, and the newly formed virus particles are released to infect other cells.
5. The lytic cycle is associated with the rapid onset of symptoms and the progression of an active infection.
Lysogenic Cycle:
1. The lysogenic cycle is characterized by the integration of the viral genetic material into the host cell's genome.
2. The viral genetic material becomes a part of the host cell's DNA and is passed on to future generations of host cells during cell division.
3. The viral genetic material remains dormant within the host cell, not actively producing new virus particles.
4. Under certain triggers, such as environmental stimuli or stress, the viral DNA can enter the lytic cycle and initiate the production of new virus particles.
5. The lysogenic cycle allows the virus to persist within the host cell without causing immediate harm, potentially resulting in long-term viral infection.
A. To determine the reproductive cycle of a virus, we can look at the information provided about the illness caused by the virus. In this case, the virus causes fever, rashes, and joint pain, and the symptoms occur within 3-5 days. Based on these symptoms, it is likely that the virus has a short incubation period and a rapid onset of symptoms. This information suggests that the reproductive cycle of the virus is most likely the lytic cycle.
In the lytic cycle, a virus uses the host's cellular machinery to produce more viral particles, leading to the destruction (lysis) of the host cell. This cycle typically occurs quickly, with the virus rapidly replicating within the host cell and causing the release of new viral particles, which can then go on to infect more cells.
B. The major differences between the lytic and lysogenic cycles are as follows:
1. Lytic Cycle:
- The lytic cycle is the reproductive cycle where the virus actively replicates inside the host cell and ultimately causes the host cell to burst or lyse, releasing new viral particles.
- It involves rapid replication and production of viral progeny.
- Symptoms of infection are immediately evident as the host cells are destroyed.
- Examples of viruses that follow the lytic cycle include the flu virus, common cold viruses, and the bacteriophage T4.
2. Lysogenic Cycle:
- The lysogenic cycle is a dormant or latent reproductive cycle where the viral genetic material (DNA or RNA) integrates into the host cell's genome without immediate reproduction.
- The integrated viral DNA is called a prophage (in bacteria) or provirus (in eukaryotes).
- The virus remains latent and may coexist with the host cell for a long period without causing any symptoms.
- Environmental factors or stressors can trigger the transition from the lysogenic to the lytic cycle where the viral genetic material gets activated, and the virus starts replicating and causing symptoms.
- Examples of viruses that can follow the lysogenic cycle include the herpes simplex virus and the human immunodeficiency virus (HIV).
In summary, the lytic cycle involves immediate replication and destruction of host cells, causing symptoms, whereas the lysogenic cycle involves the integration of viral genetic material into the host cell's genome, leading to a latent state with no symptoms until triggers activate the viral replication.