Viruses, Viroids, and Prions Overview

These flashcards cover key concepts related to viruses, including their characteristics, replication cycles (lytic and lysogenic), classification, and effects on host organisms.

What are the main characteristics of viruses?

Viruses are obligate intracellular parasites that infect host cells, cause harm, have either DNA or RNA, lack cellular structures, and depend on host cell processes for reproduction.

What is the difference between the lytic and lysogenic cycles in bacteriophage replication?

The lytic cycle actively produces virions, leading to the host cell's lysis, while the lysogenic cycle integrates viral DNA into the host genome without immediate lysis.

What is a virion?

A virion is an infectious viral particle that consists of nucleic acid surrounded by a capsid.

How do viruses attach to host cells?

Viruses use recognition elements, often embedded proteins in their capsid or envelope, to interact with specific host cell receptors.

What is the significance of the viral envelope?

The viral envelope, acquired from the host cell, provides protection from the immune system and is composed of a lipid bilayer with embedded glycoproteins.

What are the two types of genetic material found in viruses?

Viruses can have either DNA or RNA as their genetic material; this can be single-stranded (ss) or double-stranded (ds).

What factors determine the classification of viruses?

Viruses are classified based on their shape (capsid), type of nucleic acid (DNA or RNA), presence or absence of a lipid envelope, and host range.

Describe the lytic cycle of bacteriophage replication. List the stages.

The stages of the lytic cycle are: 1) Adsorption (attachment), 2) Penetration, 3) Synthesis, 4) Maturation, 5) Release.

What happens during the integration stage of the lysogenic cycle?

During the integration stage, the virus's genetic material attaches itself to the host genome, becoming a prophage.

How does lysogenic conversion affect bacterial cells?

Lysogenic conversion occurs when bacteriophages carry genes that alter the phenotype of the bacteria, such as introducing toxins.