CM1 : Virus Structure & Classification

Myco/Viro

What is the diameter of the majority of viruses?

Less than 200 nm

What techniques are used to visualize viral structures?

Electron Microscopy, X-ray Crystallography, Cryo-Electron Microscopy

What are the two main types of viral particles based on their envelope?

Enveloped and Non-enveloped (naked)

What are the two main shapes of viral capsids?

Helical and Icosahedral

What is the role of capsid proteins in viruses?

Protect the viral genome and facilitate attachment and entry

What is the significance of the T number in virology?

It summarizes the relative positions of protein hexamers and pentamers in icosahedral capsids

What is the Baltimore classification based on?

The type of genome (RNA or DNA) and its structure (single or double-stranded)

What are the three classes of fusion glycoproteins?

Type I, Type II, and Type III

Which virus is an example of a Type I fusion glycoprotein?

Dengue fever virus

What is the function of envelope glycoproteins in viruses?

Facilitate attachment and entry into host cells

What is the structure of a helical capsid?

Nucleic acid is long and linear, wrapped with multiple copies of a protein

What is an example of a virus with an icosahedral capsid?

Orthoherpesviridae

What is the genome size range for ssRNA viruses in the Baltimore classification?

3-5 kb

What are the two main families of DNA viruses mentioned?

Adenoviridae and Herpesvirales

What is a unique feature of the β-Barrel Jelly Roll domain?

It is found only in virus capsids

What is the role of matrix or tegument proteins in viruses?

Maintain the physical integrity of the viral particle and inject viral proteins into host cells

What is the significance of the ICTV classification?

It provides a systematic way to classify viruses based on molecular phylogeny

What is a characteristic of enveloped viruses?

They have a lipid bilayer surrounding their capsid

What is the genome structure of retroviruses?

RNA intermediate with a DNA phase

What is the typical diameter of icosahedral capsids?

20-30 nm

What is the function of surface glycoproteins in enveloped viruses?

Facilitate attachment and entry into host cells

What is the role of the nucleocapsid in viruses?

It protects the viral genome and assists in the entry process

What is the typical genome size for dsDNA viruses in the Baltimore classification?

Varies, typically 30-240 kb

What is a common characteristic of plant viruses?

They often have RNA genomes and can be segmented

What is the role of the viral envelope in relation to glycoproteins?

It contains glycoproteins that are essential for host cell entry

What is a notable feature of the Pandoravirus?

It has a genome size of 2.5 Mb with approximately 2500 open reading frames (orfs)