Viral Life Cycle

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What is the result of the lytic cycle in a host cell?

The phage genome replicates without destroying the host
The host cell becomes immune to phage infection
The host cell's DNA is replicated
The host cell's membrane breaks open releasing new phages (correct)

What is the function of bacterial restriction enzymes?

To assemble phage heads and tails
To synthesize viral genomes and proteins
To trigger the lysogenic cycle
To recognize and cut up certain phage DNA (correct)

What is the term for the viral DNA molecule integrated into the host cell's chromosome?

Prophage (correct)
Viral chromosome
Phage genome
Lysogenic cycle

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

Environmental signal (C) Signup and view all the answers

What is the term for phages that reproduce only by the lytic cycle?

Virulent phages (C) Signup and view all the answers

What is the result of the lysogenic cycle in a host cell?

The phage genome replicates without destroying the host (B) Signup and view all the answers

What is the term for phages that replicate by both the lytic and lysogenic cycles?

Temperate phages (B) Signup and view all the answers

What is the role of the protease enzyme in the HIV reproductive cycle?

To cut the viral polypeptide produced by translation (D) Signup and view all the answers

What is the primary route of transmission for Hepatitis B virus?

Blood and other biological fluids (B) Signup and view all the answers

What is the characteristic symptom of acute hepatitis?

Jaundice (A) Signup and view all the answers

Which virus attaches to the CD4 receptor on the surface of Th-cells?

Human Immunodeficiency Virus (C) Signup and view all the answers

What is the interval between HIV infection and the onset of AIDS?

10-15 years (B) Signup and view all the answers

What is the current status of Hepatitis C virus vaccine development?

Vaccine has not been developed yet (D) Signup and view all the answers

What is the number of people infected with HIV since the beginning of the pandemic?

85 million (B) Signup and view all the answers

What is the target of anti-retroviral therapy in HIV treatment?

HIV replication cycle (C) Signup and view all the answers

What is the definition of AIDS onset in terms of Th (CD4+) lymphocytes?

< 200 Th cells/mm3 of blood (B) Signup and view all the answers

What is the result of the inhibition of host cell gene expression by the virus?

The host cell's enzymes are used to replicate the virus (A) Signup and view all the answers

What is the function of the viral enzyme Reverse Transcriptase in retroviruses?

To convert the viral RNA into DNA (D) Signup and view all the answers

What is the outcome of the attachment and entry of a retrovirus into a host cell?

The viral RNA is converted into DNA (D) Signup and view all the answers

What is the role of the host's RNA polymerase in the replicative cycle of a retrovirus?

To transcribe the proviral DNA into RNA molecules (C) Signup and view all the answers

What is the difference between the release of non-enveloped viruses and enveloped viruses from the host cell?

Non-enveloped viruses are released by lysis, while enveloped viruses are released by budding (B) Signup and view all the answers

What is the result of the integration of the retroviral genome into the host genome?

The retrovirus becomes a provirus (D) Signup and view all the answers

What is the function of the viral glycoprotein in the replicative cycle of a retrovirus?

To bind to the host cell receptor (C) Signup and view all the answers

What is the central dogma of transfer of genetic information that retroviruses are an exception to?

DNA → RNA → protein (B) Signup and view all the answers

What is the human disease caused by consuming contaminated beef infected with prions?

Creutzfeldt-Jacob disease (CJD) (D) Signup and view all the answers

What is the characteristic of prions that allows them to cause fatal CNS infections?

Their ability to aggregate and form infectious particles (C) Signup and view all the answers

What is the term for viral diseases that affect plants?

Viral diseases in plants (D) Signup and view all the answers

What is the genome of most plant viruses composed of?

Single-stranded RNA (A) Signup and view all the answers

Which of the following viruses is responsible for causing oral herpes?

Herpes simplex virus-1 (HSV-1) (D) Signup and view all the answers

What is the term for the human disease caused by the Varicella Zoster Virus?

Chickenpox (D) Signup and view all the answers

Which of the following viruses is responsible for causing Infectious mononucleosis?

Epstein-Barr Virus (EBV) (C) Signup and view all the answers

What is the name of the coronavirus disease that was first identified in 2019?

COVID-19 (B) Signup and view all the answers

What is the name of the malignant tumor of the endothelial cells of the blood vessels?

Κaposi sarcoma (C) Signup and view all the answers

How can HIV be transmitted from mother to child?

During pregnancy, birth or breast feeding (B) Signup and view all the answers

What is the purpose of the window period in HIV diagnosis?

To indicate the time during which the virus cannot be detected but can still be transmitted (B) Signup and view all the answers

What is the main reason why there is no vaccine available for HIV?

Due to the high mutation rate of the virus (B) Signup and view all the answers

What is the purpose of Highly Active Anti-Retroviral Therapy (HAART)?

To treat HIV infection with a combination of antiretroviral drugs (A) Signup and view all the answers

What is the mechanism of action of nucleotide analogues in antiretroviral therapy?

Inhibit the viral RNA replication by being incorporated into the growing cDNA chain (A) Signup and view all the answers

What is a common problem of antiretroviral therapy?

Toxicity and resistance (C) Signup and view all the answers

How many weeks after infection can HIV be detected in the blood using RT-PCR?

3 weeks (D) Signup and view all the answers