exam 3 virus biology part one

Are viruses cells?

No, viruses are not cells and cannot make proteins on their own.

What kind of particles are viruses?

Infectious particles, not living organisms.

Can you kill a virus?

No, because viruses are not alive.

What kind of agent is a virus?

Obligate intracellular agent (multiplies only inside host cells).

What is a virion?

A fully formed, infective virus.

What are the main viral components?

1. External coating 2. Core containing nucleic acid.

What is a capsid?

A protein shell around viral nucleic acid.

What is a nucleocapsid?

Capsid + nucleic acid.

What are spikes made of and what do they do?

Spikes are glycoproteins that allow the virus to dock with host cells.

Name 3 capsid shapes.

Helical, Icosahedral, Prolate.

What does a helical capsid look like?

Rod-shaped capsomeres forming a helix around nucleic acid.

What is an enveloped virus?

A virus with a host-derived membrane that includes spikes.

What is an icosahedral capsid?

A 3D shape with 20 sides and 12 corners.

What is a prolate capsid?

Capsid shape found in bacteriophages; injects DNA using tail fibers.

What types of viral genomes exist?

DNA or RNA, single-stranded (ss) or double-stranded (ds), linear or circular.

Which virus has over 2500 genes?

Pandoravirus.

What is the first step of viral replication?

Absorption: virus binds to receptors on the host cell.

What is penetration?

The virus is engulfed via endocytosis.

What happens during uncoating?

Envelope and capsid dissolve, releasing genome into cytoplasm.

What is synthesized during viral replication?

Viral RNA, capsomeres, and spikes.

What happens in the assembly phase?

Viruses are built from parts; spikes are added.

How are enveloped viruses released?

Via budding or exocytosis.

What determines host range?

Exact fit between virus spikes and host receptors.

Which virus has a narrow host range?

Hepatitis B (only human liver cells).

Which virus has an intermediate host range?

Poliovirus (primate intestinal and nerve cells).

Which virus has a broad host range?

Rabies virus (various mammal cells).

What receptor does SARS-CoV-2 bind?

ACE2.

Where is ACE2 found?

Lungs, arteries, heart, kidney, intestines.