Micro Exam II Virology Trivia Quiz!

All viruses have a protein capsid and envelope. This means that they have a protective protein coat (capsid) surrounding their genetic material, which can be either DNA or RNA. The envelope is an additional layer that some viruses have, which is derived from the host cell's membrane. It helps the virus to enter and exit host cells. Therefore, the statement "All have a protein capsid and envelope" is true.

Adenoviidae, Poxviridae, and Herpesviridae are classified as double-stranded DNA viruses. This means that their genetic material consists of two strands of DNA, which are complementary to each other. These viruses replicate their DNA using a double-stranded intermediate, and their genome is stable and can be integrated into the host cell's DNA. This classification is based on the structure and characteristics of the viruses, as well as their mode of replication.

Cell-mediated immunity is the type of immunity that is most responsible for fighting viral infections. This form of immunity involves the activation of T cells, which directly attack and destroy virus-infected cells. T cells also release chemicals called cytokines that help coordinate the immune response and recruit other immune cells to the site of infection. In contrast, humoral immunity primarily involves the production of antibodies by B cells, which are more effective against bacterial infections. Innate immunity provides a general defense against various pathogens but is not specifically targeted towards viral infections.

Viruses are classified based on several criteria, including their type of replication (DNA or RNA, replication strategy), the structure of their infectious particle (virion), the host organism they infect, and the type of nucleic acid in their genetic material. However, they are not classified solely based on the "Structure of virus" criterion, as this aspect is considered as part of the "Structure of virion" in virus classification.

Adsorption is the process by which a virus attaches to a host membrane. It is a random and reversible process, meaning that the virus can attach and detach from the host membrane. Nonenveloped viruses attach to host cells via exposed capsid regions. However, adsorption does not require ATP (adenosine triphosphate), which is the energy currency of cells. Therefore, the statement "Requires ATP" is not true regarding adsorption.

Capsids with a helical structure do not have a fixed number of subunits and are not spherical in shape. Instead, they are typically rod-shaped or filamentous, and the number of subunits can vary, allowing them to extend to accommodate the length of the viral nucleic acid.

Viruses differ from bacteria in several ways:



Viruses do not replicate by binary fission: Unlike bacteria, which reproduce through binary fission (a form of asexual reproduction where a cell divides into two identical daughter cells), viruses can only replicate inside a living host cell. They do so by hijacking the host cell's machinery to produce new viral particles.



Viruses are smaller: Viruses are generally smaller than bacteria. Most viruses range from 20-400 nanometers in size, while bacteria typically range from 0.5-5 micrometers. This means that viruses are about a thousand times smaller than bacteria.



Viruses are obligate intracellular organisms: Viruses must invade a host cell to replicate and survive. They cannot replicate independently and rely on the host's cellular machinery. On the other hand, bacteria are independent living organisms that can replicate, grow, and metabolize nutrients on their own.

Hepadnoviridae is the correct answer because it is the only option among the given choices that is known to have mixed-stranded DNA. Mixed-stranded DNA refers to a DNA molecule that contains both a single-stranded and double-stranded regions. The other options listed are all single-stranded RNA viruses, which do not have mixed-stranded DNA.

Hematogenous spread refers to the spread of a virus through the bloodstream. In the context of the given question, it suggests that the primary replication of the virus occurs before it spreads through the bloodstream. This means that the virus initially infects a specific organ or tissue, replicates within it, and then enters the bloodstream to spread to other parts of the body. This explanation implies that neural spread, tissue spread, and viremia are not the primary modes of virus replication and spread in this case.

Negative-sense RNA viruses have a genetic material consisting of negative-sense RNA, which means that their RNA strand is complementary to the messenger RNA (mRNA) needed for protein synthesis. To replicate and express their genes, they must first transcribe their negative-sense RNA into positive-sense RNA, which can then serve as a template for protein production.