Viral Characteristics Quiz

Viruses are not considered to be truly alive because they lack the essential features common to living organisms. They do not possess a cell membrane, cytoplasm, or cellular organelles, and they cannot carry out metabolism independently, relying on host cells for their essential functions.

Viruses lack their own machinery for replication and must depend on a host cell to provide the necessary enzymes and resources to reproduce. In essence, they hijack the host cell's replication process to create more viral particles.

Despite being non-living, viruses exhibit certain life-like characteristics that set them apart from inanimate matter. For instance, their nucleic acid genome allows them to evolve through mutations and they can replicate within a host cell by exploiting the cell's machinery.

Viruses, though unable to exist independently, are capable of infecting various organisms, including animals, plants, fungi, and bacteria. They are considered obligatory intracellular parasites due to their complete dependence on a host cell for survival and replication.

Viruses can evolve over time through mutations in their genetic material, enabling them to adapt to new hosts or overcome host defenses. These changes in the virus's genetic code can result in the emergence of new strains or variants.

A two-part naming system used to classify organisms. The first part is the genus, and the second part is the species.

A system for classifying organisms based on their shared characteristics. Organisms are grouped into progressively smaller categories.

The highest taxonomic category for viruses. Names end in '-viridae'.

A lower taxonomic category for viruses within a family. Names end in '-virus'.

The scientific naming convention for viruses. It does not use all levels of the taxonomic hierarchy used for other organisms.

The specific types of organisms that a virus can infect.

Viruses that can only infect bacteria.

Viruses that can only infect fungi.

Special molecules on the surface of host cells that viruses use to attach and infect them.

If a host cell doesn't have the right receptors for a virus to attach, the virus can't infect it.

Viruses are much smaller than bacteria, typically ranging from 5 to 300 nanometers in size.

The shape of a virus's protein coat (capsid) determines its classification. This coat protects the genetic material inside.

A helical virus has a long, cylindrical protein coat that spirals around the genetic material like a spring.

A polyhedral virus has many sides, often looking like a 20-sided die (icosahedron). Its protein coat encloses the genetic material.

An enveloped virus has a helical or polyhedral core surrounded by an outer layer (envelope) made of lipids and proteins. This envelope helps the virus attach to host cells.

The entire genetic information of a virus, contained within a single molecule of DNA or RNA. It can be either circular or linear, and single- or double-stranded.

The protein shell that encloses the viral genome, protecting it from the environment and aiding in attachment to host cells.

A viral protein subunit that makes up the capsid.

The combination of the capsid and the viral genome.

A lipid-based membrane surrounding some viruses, derived from the host cell during viral replication.

A circular clearing on a lawn of bacteria formed by the growth of bacteriophages. Each plaque represents a single infectious virus particle (PFU).

A unit used to measure the number of infectious virus particles in a sample. One plaque represents one PFU.

A method used to grow and quantify bacteriophages in the laboratory. The method involves infecting a lawn of bacteria with bacteriophages and observing the formation of plaques.

A technique that utilizes a lawn of bacteria to visualize the spread of bacteriophages. It helps scientists determine the number of infectious virus particles and their ability to infect and kill bacteria.

Bacteriophages are viruses that can only infect bacteria. They are important for studying viral infection and have potential as therapeutic agents.

Viruses require a host cell to replicate, so they won't grow in a regular culture medium like bacteria do.

Animal viruses can be grown in living animals, like mice, or in fertilized eggs where the virus can infect the developing embryo.

Animal cell cultures are a method used to grow animal viruses in a laboratory setting. They involve growing cells from an animal in a controlled environment.

The changes or death of the embryo in an embryonated egg can signal viral growth.

These are specialized cells grown outside of an animal in a controlled environment. They provide a convenient and efficient way to study viruses.

Most bacteria are free-living, meaning they can survive and reproduce outside a host cell.

Rickettsias are bacteria that are obligate intracellular parasites, meaning they must live inside the cells of another organism to survive.

Rickettsias are a type of bacteria that are obligate intracellular parasites, meaning they must live inside the cells of another organism to survive.

Bacteria that can survive and reproduce outside of a host cell are called free-living. Bacteria that require a host cell to survive are called obligate intracellular parasites.

Some bacteria, like Rickettsias, need to live inside a host cell to survive. They are known as obligate intracellular parasites. Other bacteria can survive and reproduce outside of a host cell and are called free-living bacteria.

A type of protein signaling molecule that acts as a cytokine (a hormone that regulates immune cells).

Virus-infected cells release IFN, which signals nearby cells to enter a 'viral protective mode' to prevent infection.

Paracrine signaling is a type of cellular communication where cells communicate directly with their local neighbors.

IFN can induce apoptosis in virus-infected cells, causing them to self-destruct and prevent the spread of the virus.

Apoptosis is a process of programmed cell death, a crucial mechanism for removing damaged or infected cells, preventing disease.

A visible change in the appearance of cells caused by viral infection.

Tests that detect antibodies or antigens related to a specific virus in blood samples.

A highly sensitive technique that detects and amplifies specific DNA or RNA sequences from viruses.

A method used to visually count infectious virus particles (bacteriophages) by observing the formation of clearings (plaques) on a bacteria lawn.

A viral infection that results in the destruction (lysis) of the host cell.

When a virus integrates its genetic material into the host cell's DNA.

The viral DNA that is integrated into the host cell's genome during the lysogenic cycle.

The ability of a virus to either replicate immediately (lytic cycle) or integrate its DNA into the host cell's genome (lysogenic cycle).

A virus can switch from the lysogenic cycle to the lytic cycle, causing the host cell to produce new viral particles and eventually burst.

A type of viral infection where the virus remains dormant (inactive) within the host cell, often for long periods of time.

The virus responsible for chickenpox can become dormant in the body after the initial infection, and later reactivate to cause shingles.

When the varicella-zoster virus, which causes chickenpox, is reactivated after being dormant, it can cause a painful rash called shingles.

The virus causing chickenpox doesn't completely disappear from the body after the initial infection, but goes dormant in nerve cells.

The varicella-zoster virus can remain dormant for years in nerve cells, not causing any symptoms, until it is reactivated.

Although chickenpox and shingles are caused by the same virus, they present different symptoms and affect different parts of the body.

The time period between when a virus enters a host cell and begins to produce new viral particles (virions).

The stage of a viral infection where there are no complete viruses present inside the infected cell, only viral components are being produced.

The release of new viral particles from the infected cell, leading to an increase of viruses outside of the cell and the onset of disease symptoms.

A viral infection that results in a rapid onset of symptoms and is often short-lived.

A technique used to introduce new genes into cells using viruses.

When viral DNA integrates into the host chromosome, potentially carrying new genes.

The precise excision of viral DNA can sometimes include host genes, leading to their transfer.

The new virus carrying host genes can infect another cell, transferring the genes horizontally.

Viruses that can cause cancer by altering normal cell growth control mechanisms, leading to uncontrolled cell proliferation and tumor formation.

Genes carried by oncogenic viruses that become integrated into the host cell's DNA, transforming normal cells into cancerous cells.

A cell infected by an oncogenic virus exhibits increased cell division, loss of contact inhibition, and the presence of tumor-specific antigens on its surface and nucleus.

The ability of normal cells to stop dividing when they come into contact with other cells. This is lost in transformed cells, leading to uncontrolled growth.

Antigens unique to cancer cells that can be identified by the immune system. They are often found on the surface and in the nucleus of transformed cells.