An Introduction to Viruses, Viroids, and Prions

Practice flashcards for the lecture on the introduction to viruses, viroids, and prions, focusing on key concepts, definitions, and classifications.

Who first postulated that rabies was caused by a living thing smaller than bacteria?

Louis Pasteur postulated that rabies was caused by a living thing smaller than bacteria in 1884.

What is the origin of the term 'virus'?

The term 'virus' is derived from the Latin word meaning 'poison', first proposed by Dmitri Ivanovski.

What are viruses considered in terms of their presence on Earth?

Viruses are considered the most abundant microbes on Earth.

What type of organisms can viruses infect?

Viruses are obligate intracellular parasites of bacteria, protozoa, fungi, algae, plants, and animals.

What does it mean that viruses do not independently fulfill the characteristics of life?

It means that viruses cannot reproduce or carry out metabolic processes on their own and require a host cell to replicate.

What is the basic structure of a virus?

The basic structure includes a protein shell (capsid) surrounding a nucleic acid core, which can be DNA or RNA.

What are the two main types of nucleic acid found in viruses?

The two main types are DNA and RNA, but a virus will have either one, not both.

How do viruses multiply within a host cell?

Viruses multiply by taking control of the host cell's genetic material and regulating the synthesis and assembly of new viruses.

What are the two structural types of capsids in viruses?

The two structural types of capsids are helical and icosahedral.

What type of viruses typically have an envelope?

Enveloped viruses, which mostly include animal viruses, acquire their envelope when they leave the host cell.

What are cytopathic effects in virus-infected cells?

Cytopathic effects refer to changes in cells caused by viral infections, such as alterations in shape or size, and formation of inclusion bodies.

What are oncogenic viruses?

Oncogenic viruses are those that enter a host cell and can permanently alter its genetic material, potentially leading to cancer.

How are temperate phages different from lytic phages?

Temperate phages can integrate their genome into the bacterial genome and remain dormant (lysogeny), while lytic phages cause cell lysis and release of new virions.

What is the function of spikes on the viral envelope?

Spikes are exposed proteins that are essential for the virus to attach to the host cell.

What types of nucleic acids do RNA viruses contain?

RNA viruses can be single-stranded or double-stranded and may be segmented into separate pieces.

What is the significance of viral classification?

Viral classification is based on structure, chemical composition, and genetic makeup, as outlined by the International Committee on Taxonomy of Viruses.

What role do prions play in disease?

Prions are misfolded proteins that cause transmissible spongiform encephalopathies, which are fatal neurodegenerative diseases in humans and animals.