A Microbiology Knowledge Test About Viruses

Cytopathic Effects (CPEs) refer to the damage caused to cells by a virus, resulting in a change in their microscopic appearance. This can include various alterations such as cell death, changes in cell shape, size, and structure, the formation of inclusion bodies, and the disruption of cellular functions. These effects are characteristic of viral infections and can be observed under a microscope. Therefore, the statement that CPEs are virus-induced damage to the cell that alters its microscopic appearance is true.

Mimiviruses are the largest viruses, with a diameter of around 450 nm. They were discovered in 2003 and are known for their large genome size, which is comparable to some bacteria. Mimiviruses are found in amoebae and have complex structures, resembling small bacteria rather than typical viruses. They have a unique replication cycle and are considered to be a bridge between viruses and cellular life forms.

Ivanovski and Beijerinck showed that a disease in tobacco was caused by a virus.

Spikes are the component(s) of a virus that extend from the envelope for attachment. These spikes are protein structures that protrude from the viral envelope and help the virus attach to host cells. They play a crucial role in the initial stages of infection by binding to specific receptors on the surface of host cells, allowing the virus to enter and infect the cell. Spikes are found in various types of viruses, including coronaviruses, which have gained significant attention due to the COVID-19 pandemic.

Cell abnormalities resulting from a viral infection are called cytopathic effect. This refers to the structural and functional changes that occur in the infected cells as a result of viral replication. Viruses can cause various changes in infected cells, such as cell death, cell fusion, inclusion bodies formation, and changes in cell morphology. These cytopathic effects can be observed under a microscope and are important for diagnosing viral infections.

The herpes virus carries 100 genes.

Naked viruses are a type of virus that lack an outer envelope or membrane. They consist only of a nucleocapsid, which is the genetic material (DNA or RNA) surrounded by a protein coat called a capsid. This capsid protects the genetic material and aids in the virus's attachment to host cells. Therefore, the statement "Naked viruses consist only of a nucleocapsid" is true.

DNA viruses replicate and assemble in the nucleus because they require the host cell's machinery, such as enzymes and transcription factors, which are predominantly located in the nucleus. The viral DNA enters the nucleus and utilizes the host cell's DNA replication and transcription machinery to replicate and transcribe its genetic material. Once replication and transcription are complete, the viral components are assembled in the nucleus before being released from the host cell. This process allows the virus to effectively utilize the host cell's resources and machinery for its own replication and survival.

A virion is the correct answer because it refers to a fully formed virus that is capable of infecting a host cell. A virion consists of genetic material (DNA or RNA) enclosed in a protein coat called a capsid. It is the infectious form of a virus and can enter a host cell to replicate and cause infection. Prion refers to an infectious protein particle, while bacteriophage is a virus that infects bacteria.

Enveloped viruses have a lipid bilayer envelope derived from the host cell membrane. This envelope allows the virus to bud off from the host cell, acquiring the membrane as it does so. The nuclear envelope, endoplasmic reticulum, and cell membrane are all potential sites for the budding of enveloped viruses. Therefore, the correct answer is "All the above".

The envelope of a virus is derived from the host's cell membrane, nuclear envelope, or endoplasmic reticulum. This means that when a virus infects a host cell, it can acquire a portion of the host's cell membrane, nuclear envelope, or endoplasmic reticulum, which then becomes part of the virus's envelope. This envelope plays a crucial role in the virus's ability to infect other cells and evade the host's immune system. It contains viral proteins, including glycoproteins, that help the virus attach to and enter host cells.

The tail fibers on the bacteriophage are responsible for binding to the bacterial cell.

RNA viruses replicate and assemble in the cytoplasm because they lack the necessary machinery to do so in the nucleus. Unlike DNA viruses, which can utilize the host cell's nucleus for replication, RNA viruses carry their own RNA-dependent RNA polymerase enzyme that allows them to replicate their RNA genome in the cytoplasm. Additionally, the assembly of new viral particles also occurs in the cytoplasm, where the viral proteins and RNA come together to form mature viruses. Therefore, the cytoplasm serves as the primary site for replication and assembly of RNA viruses.

Parvoviruses are the smallest viruses, with a diameter of around 20 nm. This means that they are smaller in size compared to other viruses, such as mimiviruses. Parvoviruses are known for their small size and simple structure, consisting of a single-stranded DNA genome enclosed in a protein coat. They can infect a wide range of hosts, including humans, and can cause various diseases. Due to their small size, parvoviruses are able to penetrate cells easily, making them efficient at infecting their hosts.

The correct answer is Icosahedron. An icosahedron is a polyhedron with 20 equilateral triangular faces. In the context of viruses, the icosahedral shape is a common capsid shape. The capsid is the protein coat that surrounds the genetic material of a virus. The icosahedral shape allows for efficient packaging of the genetic material and provides stability to the virus. This shape is found in many viruses, including the common cold and herpes viruses.

Hepatitis D (Hep D) is a viral infection that can only occur in individuals who are already infected with Hepatitis B (Hep B). Hep D is considered a coinfection because it requires the presence of Hep B to cause the disease. Hep D alone cannot cause the disease, which is why it is necessary for a person to have Hep B in order to be at risk for Hep D. Therefore, the statement that Hep D causes coinfection with Hep B because Hep D alone can't cause the disease is true.

A virus lacks ribosomes and metabolic processes. Ribosomes are responsible for protein synthesis, which viruses cannot perform on their own and instead rely on host cells to replicate. Metabolic processes involve the conversion of nutrients into energy, which viruses also cannot carry out independently. Therefore, viruses require a host cell to provide these essential components for their survival and reproduction.

The correct answer is varicella zoster virus (chicken pox). Chickenpox is characterized by a centripetal rash that starts on the extremities and spreads to the back, torso, and face. However, it spares the palms, soles, genitalia, and mucous membranes. Rubella, mumps, and measles may cause rashes, but they do not exhibit the same pattern of spreading or sparing specific areas as seen in chickenpox.

Cold sores are caused by the herpes simplex and herpes zoster viruses. These viruses can remain dormant in the body for long periods of time without causing any symptoms. However, they can become active and cause cold sores when triggered by factors such as stress, illness, or sun exposure. This is an example of a latent viral infection, where the virus remains in the body in a dormant state and can reactivate later to cause symptoms.

Chickenpox vaccine is a live vaccine, which means it contains a weakened form of the virus. Live vaccines often require a double dose to ensure maximum effectiveness. The first dose helps the immune system recognize and respond to the virus, while the second dose boosts the immune response and provides long-lasting protection. This double dose approach helps to ensure that the vaccine provides adequate immunity against chickenpox.

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A negative sense/strand RNA virus must be converted to a positive strand/sense in order to make mRNA. This is because the viral proteins are synthesized using mRNA, and the viral genome is in the form of negative sense RNA. Therefore, the negative sense RNA must first be converted to a positive sense strand, which can then serve as a template for mRNA synthesis.

All the viruses mentioned in the options, namely measles, influenza, and rabies, are helical in shape and have an enveloped structure. The helical shape refers to the spiral-like structure of the virus, while the envelope signifies the presence of a lipid membrane surrounding the viral particle. Therefore, all the given options meet the criteria of being helical and enveloped viruses.

During the eclipse phase of a viral growth curve, the virus is not detected because it is inside the host cell and has not yet started replicating. This phase occurs after the virus has entered the host cell and released its genetic material, but before new viral particles are assembled and released. The eclipse phase is characterized by the absence of viral particles in the extracellular environment, as they are still in the process of being synthesized within the host cell.

A positive-strand RNA virus can be used directly to translate viral proteins because it carries the genetic information in the same orientation as the host cell's mRNA. This allows the host cell's ribosomes to recognize and translate the viral RNA into viral proteins without the need for any conversion or modification.

The capsid or envelop of a virus has multiple functions. It protects the nucleic acid genome from damage during the extracellular passage of the virus, aids in the process of entry into the cell, and in some cases, packages enzymes essential for the early steps of the infection process. Therefore, all the options mentioned in the question (protecting the nucleic acid genome, aiding in cell entry, packaging enzymes) are functions of the capsid or envelop.

Viruses are known to vary in size, with the smallest ones measuring around 20 nanometers (nm) and the largest ones measuring up to 450 nm. This size range allows viruses to be smaller than most bacteria and other microorganisms, making them capable of infecting these larger organisms. The given answer, "20-450 nm," accurately represents the size range of viruses.

Both Hep B and Herpes virus are icosahedral viruses with an enveloped. The icosahedral shape refers to the geometric shape of the virus, which is composed of 20 equilateral triangular faces. The envelope refers to a lipid bilayer that surrounds the virus, which is derived from the host cell membrane. Both Hep B and Herpes virus possess these characteristics, making them the correct answer.

Blueberry Muffin Syndrome is a rare neonatal skin disorder caused by the rubella virus. Rubella, also known as German measles, is a contagious viral infection that can cause various complications during pregnancy. If a pregnant woman contracts rubella, the virus can be transmitted to the fetus, leading to congenital rubella syndrome. One of the manifestations of this syndrome is Blueberry Muffin Syndrome, characterized by the presence of small, raised, red or purple spots on the baby's skin. These spots resemble blueberries, hence the name of the syndrome.

During the release phase, a virus obtains its envelope. This is the final stage of the viral life cycle, where the newly formed viral particles are released from the host cell. The envelope is acquired as the virus buds off from the host cell membrane or from intracellular membranes. The envelope is derived from the host cell's membrane and contains viral proteins that help the virus evade the immune system and facilitate infection of new host cells.

A provirus is a virus that has incorporated its genetic material into the DNA of the host cell. The Measles virus is an example of a provirus. This means that the viral DNA becomes a permanent part of the host cell's DNA and can be passed on to daughter cells during cell division. The provirus remains dormant within the host cell until it is activated to produce new virus particles. This allows the virus to persist within the host for long periods of time.

TMV (Tobacco Mosaic Virus) is a naked virus with a helical structure. Naked viruses lack an outer envelope, making them more resistant to disinfectants and environmental conditions. TMV has a rod-shaped helical structure, which is characteristic of many plant viruses. In contrast, Influenza, measles, and rabies are all enveloped viruses, meaning they have an outer lipid membrane derived from the host cell.

Loeffler and Frosch discovered that an animal virus causes foot and mouth disease in cattle.

A mononucleated cell is not considered a cytopathic effect. Cytopathic effects refer to visible changes in cells caused by viral infections or other factors. Transformation, cell fusion, and inclusion bodies are all examples of cytopathic effects. However, a mononucleated cell simply refers to a cell with a single nucleus, which is a normal characteristic and not indicative of any specific cytopathic effect.

Rubella syndrome refers to the set of birth defects that can occur in a baby if the mother contracts rubella (German measles) during pregnancy. The correct answer is "first trimester" because it is during this period, which lasts from conception to week 12 of pregnancy, that the baby is most vulnerable to the harmful effects of rubella. If a pregnant woman contracts rubella during the first trimester, there is a higher risk of the baby developing congenital rubella syndrome, which can lead to various complications such as hearing loss, heart defects, and intellectual disabilities.

Tropism refers to the binding of the virus spikes to a specific receptor on the host cell. This interaction allows the virus to attach itself to the host cell and initiate the infection process. It is an essential step for the virus to enter the host cell and replicate. Parasitism refers to a relationship where one organism benefits at the expense of another, which is not applicable in this context. Attachment and binding are related to the process of tropism, but they do not fully capture the specificity and interaction between the virus spikes and the host cell receptor.