Chapter 13 Notes: Prions, Viruses, Viroids, and Viral Structure

These flashcards cover key concepts from the notes on prions, viruses, viroids, and their structures, functions, and relationships.

What are viruses?

Viruses are obligate intracellular parasites that must infect a host cell to reproduce.

How do viruses differ from bacteria?

Unlike bacteria, viruses do not have ribosomes, cannot make ATP, and cannot produce proteins on their own.

What is a virion?

A virion is the complete virus particle, consisting of nucleic acids, a capsid, and sometimes an envelope.

What are the main parts of a virus?

The main parts of a virus include nucleic acids (DNA or RNA), a capsid (protein coat), and sometimes an envelope (lipid layer).

What is the lock-and-key mechanism in virus infection?

The lock-and-key mechanism refers to the specific interaction between viral attachment proteins (keys) and host cell receptors (locks) which determines infection.

What are the types of viruses based on structure?

The types of viruses include naked viruses (capsid only), enveloped viruses (capsid + lipid envelope), helical viruses (rod-shaped), polyhedral viruses (icosahedral shape), and complex viruses (irregular structure).

What are bacteriophages?

Bacteriophages are viruses that infect bacteria and can be grown on bacterial lawns to observe their effects.

What is the lytic cycle of viral infection?

In the lytic cycle, a virus infects a host cell, uses the host to replicate, causes the host cell to lyse (burst), and releases new viruses.

What is the lysogenic cycle?

The lysogenic cycle is a dormant stage where viral DNA integrates into the host DNA and is replicated along with it until triggered to enter the lytic cycle.

What are retroviruses?

Retroviruses, such as HIV, convert RNA into DNA using reverse transcriptase and integrate into the host genome permanently.

What is the effect of oncogenic viruses on cells?

Oncogenic viruses can cause cancer by affecting proto-oncogenes and leading to uncontrolled cell division.

What are prions?

Prions are misfolded proteins that can induce other proteins to misfold, leading to diseases such as Mad Cow Disease.

How do prions cause diseases?

Prions cause diseases by inducing normal proteins to fold incorrectly, which leads to neurological damage.

What diseases are associated with prions?

Prion-related diseases include spongiform encephalopathies such as Mad Cow Disease.