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All questions of Viruses for MCAT Exam

Antiviral drugs typically target:
  • a)
    Viral proteins
  • b)
    Host cell proteins
  • c)
    Viral envelopes
  • d)
    Host cell membranes
Correct answer is option 'A'. Can you explain this answer?

Hazel Hill answered
Target of Antiviral Drugs: Viral Proteins
Antiviral drugs typically target viral proteins to inhibit viral replication and treat viral infections. Here's how these drugs work:

1. Viral Replication
- Viruses rely on host cells to replicate and spread. They use their own viral proteins to hijack the host cell machinery.
- Antiviral drugs target specific viral proteins involved in crucial steps of the viral replication cycle, such as viral entry, genome replication, protein synthesis, and assembly of new viral particles.

2. Mechanism of Action
- Antiviral drugs can target different viral proteins, depending on the type of virus being treated. For example, drugs targeting the HIV protease enzyme prevent the virus from maturing and infecting new cells.
- By inhibiting viral proteins, these drugs disrupt the viral life cycle and reduce the viral load in the body, ultimately helping the immune system fight off the infection.

3. Specificity
- Targeting viral proteins allows antiviral drugs to be more specific in their action, as they are designed to interfere with viral processes without affecting normal host cell functions.
- This specificity helps to minimize side effects and improve the overall safety profile of antiviral medications.
In conclusion, antiviral drugs are designed to target viral proteins to disrupt viral replication and treat viral infections effectively. By focusing on specific viral targets, these drugs help to combat viral diseases while minimizing harm to the host cells.

The process by which a virus integrates its genetic material into the host cell's genome is called:
  • a)
    Lysis
  • b)
    Budding
  • c)
    Lysogeny
  • d)
    Replication
Correct answer is option 'C'. Can you explain this answer?

Orion Classes answered
Lysogeny is the process in which a virus integrates its genetic material, specifically its DNA, into the host cell's genome. The viral DNA, known as a prophage, becomes a permanent part of the host cell's DNA and can be replicated along with the host cell's genome.

The protein coat of a virus is primarily responsible for:
  • a)
    Protecting the viral genome
  • b)
    Facilitating viral attachment to host cells
  • c)
    Replicating the viral genome
  • d)
    Assisting in viral protein synthesis
Correct answer is option 'A'. Can you explain this answer?

Orion Classes answered
The protein coat, or capsid, of a virus serves as a protective layer around the viral genome. It helps shield the genetic material from damage, such as enzymatic degradation, while the virus is outside the host cell.

The envelope of a virus is derived from:
  • a)
    The host cell's plasma membrane
  • b)
    The host cell's cytoplasm
  • c)
    The viral capsid
  • d)
    The viral genome
Correct answer is option 'A'. Can you explain this answer?

Orion Classes answered
The envelope of a virus is derived from the host cell's plasma membrane or an internal membrane, such as the endoplasmic reticulum or Golgi apparatus. As the virus exits the host cell during the budding process, it acquires a portion of the host's membrane, which becomes part of its envelope.

Which of the following is NOT a component of a typical virus?
  • a)
    Protein coat (capsid)
  • b)
    Nucleic acid(DNA or RNA)
  • c)
    Lipid membrane (envelope)
  • d)
    Ribosomes
Correct answer is option 'D'. Can you explain this answer?

Orion Classes answered
Viruses are acellular particles composed of a protein coat called a capsid and a nucleic acid core (DNA or RNA). Some viruses may also possess a lipid membrane called an envelope. However, viruses do not contain ribosomes, which are cellular organelles involved in protein synthesis.

The immune response to a viral infection primarily targets:
  • a)
    Viral proteins on the cell surface
  • b)
    Viral RNA or DNA in the host cell
  • c)
    Viral capsids within the host cell
  • d)
    Viral envelopes released from the host cell
Correct answer is option 'B'. Can you explain this answer?

Orion Classes answered
The immune response primarily targets viral RNA or DNA within the host cell. Immune cells recognize and respond to viral genetic material as a sign of infection, triggering a cascade of immune responses to eliminate the infected cells and control the spread of the virus.

Retroviruses are unique among viruses because they:
  • a)
    Lack an envelope
  • b)
    Contain RNA as their genetic material
  • c)
    Replicate their RNA genome using reverse transcriptase
  • d)
    Only infect plants
Correct answer is option 'C'. Can you explain this answer?

Orion Classes answered
Retroviruses are RNA viruses that replicate their RNA genome using an enzyme called reverse transcriptase. Reverse transcriptase converts the viral RNA into DNA, which can then integrate into the host cell's genome. This unique characteristic sets retroviruses apart from other types of viruses.

The release of enveloped viruses from the host cell occurs through:
  • a)
    Lysis of the host cell
  • b)
    Budding from the host cell membrane
  • c)
    Formation of viral inclusion bodies
  • d)
    Conjugation with other infected cells
Correct answer is option 'B'. Can you explain this answer?

Orion Classes answered
Enveloped viruses exit the host cell through a process called budding. During budding, the virus acquires an envelope derived from the host cell's membrane, and it buds off from the cell surface, taking a portion of the membrane with it. This process allows the virus to exit the cell without immediately lysing it.

The reproductive cycle of a virus typically involves:
  • a)
    Binary fission
  • b)
    Meiosis
  • c)
    Mitosis
  • d)
    Hijacking host cellular machinery
Correct answer is option 'D'. Can you explain this answer?

Orion Classes answered
Viruses lack the necessary cellular machinery to replicate on their own. Instead, they hijack the host cell's machinery to reproduce. They utilize the host cell's enzymes, ribosomes, and metabolic pathways to synthesize viral proteins and replicate their genetic material.

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