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Questions and Answers

What is a characteristic of a virus?

Capability to transform energy

Ability to reproduce on its own

Made up of cells

Obligate intracellular parasite (correct)

Which type of RNA can work as mRNA?

DNA

Double-stranded RNA

Negative sense RNA

Positive sense RNA (correct)

What is the function of the capsid?

To provide energy to the virus

To synthesize mRNA

To transform the host cell

To protect the viral genome (correct)

What is a result of a lytic viral infection?

The cell dies Signup and view all the answers

How do viruses acquire an envelope?

By taking it from the host cell Signup and view all the answers

What is the purpose of viral mRNA synthesis?

To synthesize viral proteins Signup and view all the answers

What is a characteristic of oncogenic viruses?

They transform host cells into cancer cells Signup and view all the answers

What is a strategy used by viruses to survive?

Finding the right type of host cell Signup and view all the answers

Approximately what percentage of deaths in the world are caused by infectious diseases?

One-fourth Signup and view all the answers

Which of the following microorganisms was discovered by Koch?

All of the above Signup and view all the answers

What is the main difference between prokaryotic and eukaryotic cells?

All of the above Signup and view all the answers

What are Koch's Postulates used to establish?

A causal relationship between a microbe and a disease Signup and view all the answers

What is the fourth criterion of Koch's Postulates?

The pathogen must be reisolated from the new host and shown to be the same as the originally inoculated pathogen Signup and view all the answers

What is the characteristic of viral structure?

No cells Signup and view all the answers

What is the name of the disease caused by the bacterium Mycobacterium tuberculosis?

Tuberculosis Signup and view all the answers

What is the term for the movement of people and goods across the globe?

Globalization Signup and view all the answers

What is a key feature of viral genomes?

They can be copied by cellular machinery with the help of viral proteins. Signup and view all the answers

What is the purpose of transporting viral genome, capsid, and envelope proteins?

To assemble new viral particles. Signup and view all the answers

How do viruses evade host defenses?

By evolving ways to fight back against host defenses. Signup and view all the answers

What is a characteristic of prions?

They are infectious agents composed of misfolded proteins. Signup and view all the answers

What is the result of prion accumulation in neurons?

The formation of amyloid plaques, leading to toxicity for nerve cells. Signup and view all the answers

What happens to the brain as a result of prion accumulation?

It becomes like a sponge due to the accumulation of prion proteins. Signup and view all the answers

What is the role of viral proteins in viral replication?

They cooperate with cellular machinery to copy the viral genome. Signup and view all the answers

What is the name of the toxin that can contaminate grains and is very toxic?

Aflatoxin Signup and view all the answers

Why must viruses propagate themselves in new cells?

To ensure their survival. Signup and view all the answers

Which type of fungal infection involves the outer layer of the skin, epidermis, and dermis, and is transmitted by direct contact?

Cutaneous mycosis Signup and view all the answers

What is the term for fungal diseases caused by the ingestion of toxins produced by fungi?

Mycotoxicosis Signup and view all the answers

What is the type of fungal reproduction that involves the production of asexual spores by mitosis?

Asexual spores by mitosis Signup and view all the answers

What is the term for the cell wall component of fungi that is a polymer of acetilglucosamine?

Chitin Signup and view all the answers

What is the type of fungal infection that affects subcutaneous tissues, muscles, and lymphatic tissue, and is transmitted by injuries or wounds?

Subcutaneous mycosis Signup and view all the answers

What is the term for the type of fungal infection that is caused by the inhalation of fungal spores and can affect various organs in the body?

Systemic mycosis Signup and view all the answers

What is the term for the type of fungal infection that requires a compromised host and can cause deep mycosis?

Opportunistic mycosis Signup and view all the answers

What is the function of pili in bacterial cells?

To join bacterial cells for partial DNA transfer Signup and view all the answers

What is the main function of flagella in bacteria?

Motility Signup and view all the answers

What is the composition of the bacterial cell wall?

Peptidoglycan and teichoic acid Signup and view all the answers

What is the function of the capsule in bacteria?

Escapes from phagocytosis Signup and view all the answers

What is the characteristic of bacterial morphology known as 'vibrio'?

Corkscrew form Signup and view all the answers

What is the term for the resistance forms produced by some Gram-positive bacteria?

Endospores Signup and view all the answers

What is the type of bacterial disease caused by Bacillus anthracis?

Anthrax Signup and view all the answers

What is the term for the 'stickiness' factor that helps bacteria to adhere to surfaces?

Adherence factors Signup and view all the answers

Study Notes

Viral Morphology and Structure

A virus is a submicroscopic entity consisting of a single nucleic acid surrounded by a protein coat (capsid) and capable of replication only within living cells of bacteria, animals, or plants.
Viruses are obligate intracellular parasites, meaning they are not made of cells, cannot reproduce on their own, do not grow or undergo division, and do not transform energy.
Viruses lack machinery for protein synthesis.

Shapes of Viruses

Viruses can have helical, polyhedral, spherical, or bacteriophage shapes.
The capsid is formed from identical protein subunits called capsomeres.

Nucleic Acid

Viruses can have DNA or RNA as their genetic material.
DNA can be single-stranded or double-stranded, while RNA can be single-stranded or double-stranded.
RNA can be positive sense RNA, which works as mRNA, or negative sense RNA, which must be converted to positive-sense RNA by an RNA-dependent polymerase before translation.

Envelope

Some viruses have an envelope, which is acquired from the host cell during viral replication or release.
The envelope is a portion of the host cell's membrane system.

Effects of Viral Infections

Viral infections can cause cytocide, leading to cell death.
Persistent viral infections allow cells to remain alive.
Latent infections have a period between infection and symptom onset.
Oncogenic viruses can transform into chromosomes, leading to benign or malignant (cancerous) transformations.

Strategies for Virus Survival

Viruses must find and invade a host cell, making proteins and genomes to replicate.
Viruses use mRNA synthesis strategies to overcome host defenses.

Importance of Infectious Diseases in Public Health

According to the World Health Organization (WHO), infectious diseases cause almost a quarter of deaths worldwide.
90% of deaths are due to VIH/AIDS, tuberculosis, diarrhea, malaria, measles, and pneumonia.
Emerging and re-emerging infectious diseases, such as SARS, Creuzfeldt-Jakob, dengue, Ebola, cholera, and Chikungunya fever, are a concern.

Discovery of Microorganisms and Infectious Diseases

Robert Koch (1876) and Louis Pasteur (1877) discovered the relationship between microorganisms and infectious diseases.
Koch's Postulates establish a cause-and-effect relationship between a microbe and a disease.

Eukaryotes, Prokaryotes, and Viruses

Eukaryotes have organized chromosomes in a nucleus, with membranous organelles like mitochondria and Golgi.
Prokaryotes lack a nucleus and membranous organelles, with a single loop of DNA.
Viruses are not cells and require a host cell to replicate.

Prions

Prions are infectious agents, specifically misfolded proteins that can cause diseases.
Prions are not considered living organisms.

Fungi

Fungi have a cell wall composed of chitin (a polymer of acetilglucosamine).
Fungi have a plasma membrane with ergosterol.
Fungi can be yeasts or filamentous fungi (moulds).
Filamentous fungi have hyphae, which form mycelium.

Types of Fungal Diseases

Fungal diseases can be intoxifications, infections (mycoses), or hypersensitivity reactions (allergies).

Bacteria

Bacteria have external structures like fimbriae or pili, flagella, glycocalyx, cell wall, and plasmatic membrane.
Bacteria can cause diseases, including anthrax, tetanus, gas gangrene, and botulism.

Bacterial Morphology and Structure

Bacteria can be spherical (cocci), rod-shaped (bacilli), corkscrew-shaped (vibrio), or helical (spirochetes).
Bacteria can have endospores, which are resistant forms produced by some Gram-positive bacteria.

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