Al-Turath University College of Pharmacy Virology Lecture 1

What is the primary basis for distinguishing naked viruses from enveloped viruses?

The presence or absence of a viral lipid envelope (correct)
The shape of the capsid
The method of release from the host cell
The type of genetic material

Which property of naked viruses makes them stable in a hostile environment?

The lack of a lipid sheath (correct)
The method of release from the host cell
The presence of a viral lipid envelope
The presence of a nucleocapsid

Which type of virus morphology is represented by Figure (C) in the text?

Bacteriophage with a prolate capsid (correct)
Brick-shaped virus
Helical virus
Icosahedral virus

Which property of naked viruses allows them to infect the GI tract and survive the acid and bile?

The lack of a lipid sheath (B) Signup and view all the answers

What is the primary function of the nucleocapsid in naked viruses?

To allow the virus to enter cells (D) Signup and view all the answers

Which property of naked viruses allows them to spread easily via hands, dust, and fomites?

The ability to sustain in a dry environment (A) Signup and view all the answers

What is the primary focus of the field of virology?

The study of viral nature and the relationship between viruses and hosts (A) Signup and view all the answers

What technique allows us to visualize viruses today?

Electron microscopes (C) Signup and view all the answers

Who is credited as the original discoverer of viruses and a founder of the field of virology?

Dmitri Ivanovski (B) Signup and view all the answers

Why are viruses not included in the tree of life?

They are not composed of cells (A) Signup and view all the answers

What is the term used to describe viruses in relation to their host cells?

Obligate intracellular parasites (A) Signup and view all the answers

What is the process by which new virus particles (virions) are formed?

The viral components are assembled in the host cell by a process called virion assembly (B) Signup and view all the answers

What are the two main components of the viral complex of proteins?

Structural proteins and Enzymes (A) Signup and view all the answers

What is the function of a protomer in viral architecture?

Binds to nucleic acid periodically (C) Signup and view all the answers

Which type of symmetry involves protein subunits being bound in a periodic manner to the viral nucleic acid, creating rod-shaped or filamentous virions?

Helical symmetry (B) Signup and view all the answers

What is the primary characteristic of cubic symmetry (icosahedral) viral architecture?

Arrangement of capsomeres in triangular patterns (A) Signup and view all the answers

Why are capsomeres composed of protomers important in viral structure?

They make up the capsid, a protein coat (C) Signup and view all the answers

Which type of virus has a nucleocapsid coiled inside a lipid-containing envelope as part of its structure?

Orthomyxoviruses (D) Signup and view all the answers

What is the primary role of virions in the viral life cycle?

To initiate infection in a new host cell (D) Signup and view all the answers

Which of the following statements about the historical study of viruses is incorrect?

The term 'virus' is derived from the Latin word for 'poison' or 'slimy matter' (B) Signup and view all the answers

Which of the following is NOT a characteristic of viruses according to the definition provided?

Viruses can replicate independently outside of host cells (C) Signup and view all the answers

What is the primary function of ribosomes in the viral life cycle?

To synthesize viral proteins (D) Signup and view all the answers

Which of the following statements about viruses is true?

Viruses are composed of organic material (C) Signup and view all the answers

What is the primary role of the host cell's metabolic machinery in the viral life cycle?

To synthesize viral proteins (B) Signup and view all the answers

According to the passage, what is the main idea behind the regressive hypothesis?

Viruses may have once been small cells that parasitized larger cells, and over time they lost the genes not required for their parasitism. (D) Signup and view all the answers

What does the passage say about the bacteria rickettsia and chlamydia in relation to the regressive hypothesis?

They are living cells that can reproduce only inside host cells, which lends support to the regressive hypothesis. (A) Signup and view all the answers

What is the main idea behind the cellular origin hypothesis according to the passage?

Viruses may have evolved from bits of DNA or RNA that "escaped" from the genes of a larger organism. (B) Signup and view all the answers

What are transposons, and how do they relate to the cellular origin hypothesis?

Transposons are molecules of DNA that replicate and move around to different positions within the genes of the cell, and they could be the origin of some viruses. (B) Signup and view all the answers

What is the main criticism of the cellular origin hypothesis mentioned in the passage?

The cellular origin hypothesis did not explain the complex capsids and other structures on virus particles. (C) Signup and view all the answers

What is the other name given to the regressive hypothesis in the passage?

The degeneracy hypothesis or reduction hypothesis (A) Signup and view all the answers