Viruses, Microbiota, and Disease: Key Concepts for Biology Students

What is a false statement about viruses?

Viruses can grow on any surface.

What are some characteristics of viruses?

Viruses are extremely small, can cause cancer, can remain dormant, cause disease, and can infect most life forms.

What is the size range of viruses?

Pithovirus ~ 1500 nm, Mimivirus ~ 400 nm, Parvoviruses ~ 20 nm.

What are the main components of a virus structure?

Nucleic acid (DNA or RNA), protein coat (capsid), and sometimes an envelope.

What types of nucleic acids can be found in viruses?

ss RNA, ds RNA, ss DNA, and ds DNA.

What is the function of the capsid in a virus?

The capsid protects the nucleic acid and aids in host recognition and entry.

What shapes can viruses have?

Icosahedral, helical, complex, filamentous, bullet-shaped, and cone-shaped.

What is the role of protein spikes in viruses?

Protein spikes are involved in enzyme function and attachment to host cells.

What are the stages of the viral life cycle?

Adsorption, entry, nucleic acid replication, protein synthesis, and exit.

How does a virus enter a host cell?

Through receptor-mediated endocytosis or envelope/membrane fusion.

What is the special case of retroviruses in terms of nucleic acid replication?

Retroviruses convert RNA into DNA using reverse transcriptase.

What happens during the viral protein synthesis stage?

Translation of mRNA and self-assembly of viral components.

What are the two types of viral life cycles?

Lytic cycle and lysogenic cycle.

What is the classification of viruses based on?

Host range, structure (nucleic acid, capsid, envelope), and size.

What are some examples of animal virus families?

Herpesviridae, Adenoviridae, Papovaviridae, Hepadnaviridae, Paramyxoviridae, Orthomyxoviridae, Filoviridae, Retroviridae, Coronaviridae.

What are viroids?

Circular ssRNA that cause diseases in plants.

What are prions?

Misfolded proteins that can cause neurodegenerative diseases.

What is the role of reverse transcriptase in retroviruses?

It converts viral RNA into DNA for integration into the host genome.

What is the significance of the term 'provirus'?

A provirus is viral DNA that has integrated into the host's DNA.

What is an example of a virus that uses receptor proteins for entry?

HIV uses CD4 and CCR5/CXCR4 as receptor proteins.

What can trigger cell death during the viral life cycle?

The release of new virions often involves host cell lysis.

What is the function of integrase in HIV?

Integrase inserts HIV DNA into the host DNA.

What is symbiosis?

A relationship where two different organisms live together, often involving a host and a microbe.

What are the four types of symbiotic relationships?

Mutualism, Commensalism, Parasitism, and Amensalism.

What is mutualism?

A symbiotic relationship where both organisms benefit.

What is commensalism?

A symbiotic relationship where one organism benefits and the other is unaffected.

What is parasitism?

A symbiotic relationship where one organism benefits at the expense of the other.

What is amensalism?

A relationship where one organism is harmed while the other is unaffected, often due to competition.

What is the role of microbiota?

Microbiota refers to all the microbes in and on the body, playing crucial roles in health and disease.

How does the human microbiota develop?

It is established at birth and influenced by environmental exposure, diet, and other factors.

What are the physical defenses of the body against microbes?

Skin and mucous membranes act as barriers to prevent microbial entry.

What are mechanical defenses in the body?

Movements such as mastication, peristalsis, and ciliary action that help remove microbes.

What are biochemical defenses?

Secretions such as lysozyme, stomach acid, and bile that help eliminate microbes.

What is innate immunity?

The body's first line of defense that responds to general threats without prior exposure.

What is adaptive immunity?

A specific immune response that develops over time and provides long-lasting protection.

What factors can change the human microbiota?

Introduction of new microbes, changes in the host environment, and factors like age and diet.

What is the significance of probiotics?

Probiotics like Bifidobacteria and Lactobacillus can promote health and prevent infections.

What are fecal transplants used for?

They are used to treat conditions like C. difficile infections with high cure rates.

What is the role of Lactobacillus in the female genital tract?

Lactobacillus helps maintain a healthy balance and prevents infections.

What are common locations for Staphylococcus in the human body?

Skin and nostrils.

What is the chain of infection in disease pathogenesis?

It includes maintaining a reservoir, transmission, colonization, invasion, evasion of defenses, causing damage, and leaving the host.

What are reservoirs in the context of infectious diseases?

Natural habitats where pathogens live and multiply, such as humans, animals, and the environment.

What is an example of a zoonotic disease?

Lyme Disease caused by Borrelia.

What is the role of opportunistic pathogens?

They can cause disease when the host's immune defenses are compromised.