Trivia: Microbiology Quiz On DNA And Virus

A single virus particle is called a virion. A virion is the complete infectious form of a virus, consisting of genetic material (DNA or RNA) surrounded by a protein coat called a capsid. The virion is the unit of transmission and is responsible for infecting host cells and reproducing.

The correct order for the stages of a phage infection is attachment, penetration, transcription, replication of nucleic acid and protein, assembly, and release. This sequence follows the typical steps of a phage infection, starting with the attachment of the phage to the host cell, followed by the penetration of the phage into the host cell. Once inside, the phage undergoes transcription to produce viral proteins and replication of its nucleic acid. The newly synthesized viral components then assemble to form new phage particles. Finally, the mature phage particles are released from the host cell to infect other cells.

The lytic cycle causes lysis, which refers to the bursting or destruction of the host cell. During the lytic cycle, a virus infects a host cell, takes over its machinery to replicate itself, and eventually causes the cell to burst open, releasing new viral particles. This process allows the virus to spread and infect other cells. Lysis is the result of the lytic cycle and is a crucial step in the viral life cycle.

Bacteriophages are viruses that specifically infect bacteria. They are composed of genetic material (DNA or RNA) surrounded by a protein coat. Bacteriophages attach to the surface of bacterial cells and inject their genetic material into the host cell. Once inside, the phage genetic material takes control of the bacterial machinery, redirecting it to produce more phages. Eventually, the bacterial cell bursts, releasing new phages to infect other bacterial cells. Therefore, bacteriophages are the correct term to describe viruses that infect bacteria.

A virion is a complete virus particle that is composed of proteins and genetic material, which can be either RNA or DNA. The proteins form the protective coat of the virus, called the capsid, which encloses and protects the genetic material. The genetic material contains the instructions for the virus to replicate and infect host cells. Therefore, the correct answer is "protein, and either RNA or DNA."

Specialized transduction is a process in which a few specific genes are transferred from one bacterium to another using a defective virus. This type of transduction only involves genes that are located near the site where the viral DNA integrates into the bacterial genome. Therefore, the correct answer states that specialized transduction involves the transfer of a few specific genes, utilizes a defective virus, and only involves genes near the viral DNA integration site.

The assembly of the T4 phage may involve some self-assembly, meaning that certain components of the phage can come together on their own without external assistance. Additionally, it may also involve the use of scaffolds, which are structures that provide support and organization during the assembly process. This suggests that the assembly of the T4 phage is not entirely dependent on self-assembly or scaffolds alone, but rather a combination of both processes.

Viruses probably keep the numbers of bacteria in check because they infect and kill bacteria, preventing their population from growing uncontrollably. Additionally, viruses are also active in passing DNA from one bacterium to another through a process called transduction. This allows for the transfer of genetic material between bacteria, potentially leading to genetic diversity and adaptation. Therefore, the correct answer is that viruses probably keep the numbers of bacteria in check and are active in passing DNA from one bacterium to another.

The term "bacillus" refers to a specific shape of bacteria, not viruses. Viruses can have different shapes, such as icosahedral (isometric), helical, or complex. However, "bacillus" is not a shape that is typically associated with viruses.

All of the choices are correct because the given statements are all true. The majority of phages are indeed temperate, meaning they can either enter a lytic cycle and cause cell lysis or integrate their DNA into the host DNA as a prophage. When integrated, the phage DNA is called a prophage. Lambda is a well-known example of a temperate phage. Therefore, all the statements provided are accurate and can be considered correct.

Lysogenic cells are immune to infection by the same virus because they have already been infected and integrated the viral DNA into their own genome. This integration prevents the virus from infecting the cell again. Additionally, lysogenic cells may have new properties because the viral DNA can provide new genes and functions to the host cell. These new properties can be beneficial or detrimental to the cell, depending on the specific viral DNA integrated.

The protein projections on the surface of a virus that are involved in attachment to the host cell are called spikes. These spikes help the virus to bind to specific receptors on the surface of the host cell, allowing the virus to enter and infect the cell. This attachment is crucial for the virus to initiate the infection process and replicate within the host cell.

RNA phages are viruses that infect bacteria and have RNA as their genetic material. They typically contain single-stranded RNA (ssRNA) as their genome. This means that the genetic information of the phage is encoded in a single strand of RNA, which is used to replicate and produce viral proteins within the host bacterium. The other options, dsRNA, dsDNA, and ssDNA, are not typically found in RNA phages as they do not possess these types of genetic material.

A temperate phage may be lysogenic, meaning it can integrate its DNA into the host cell's genome and remain dormant for an extended period of time without killing the host cell. However, it may also enter a lytic life cycle, where it replicates and eventually lyses the host cell to release new viral particles. Therefore, a temperate phage can exhibit both lysogenic and lytic behaviors, entering a lysogenic or lytic life cycle shortly after entering the host cell.

T4 is one of the most intensively studied virulent phages that infect E. coli. It is widely used in molecular biology research due to its well-characterized genome and its ability to efficiently infect and replicate within E. coli cells. T4 is a large, complex phage that injects its DNA into the host cell and takes over the cellular machinery to produce more phage particles. Its study has provided valuable insights into phage biology, bacterial genetics, and the mechanisms of viral infection.

Phage-encoded enzymes are produced in a sequential manner, meaning that they are synthesized one after another in a specific order. This sequential production allows for efficient regulation and coordination of enzyme activity during viral replication. Additionally, these enzymes are used to customize the host cell for viral production. They modify the cellular machinery and processes to favor the production and release of new phage particles. Therefore, the correct answer is that phage-encoded enzymes are produced in a sequential manner AND used to customize the cell for viral production.

Viruses are considered metabolically inert because they lack the necessary cellular machinery to carry out metabolic processes on their own. Unlike living cells, viruses cannot generate ATP from glucose or any other energy source, nor can they move using cilia or any other means. They rely on host cells to provide the necessary resources and machinery for their replication and survival. Therefore, the correct answer is that viruses are metabotically inert.

Once inside the host cell, phage DNA can undergo replication, transcription, and may also be degraded by bacterial nucleases. These processes are all possible outcomes once the phage DNA enters the host cell. Therefore, the correct answer is that all of the choices are correct.

The T4 phage uses its tail as a "hypodermic needle" to inject its DNA into the E. coli cell during penetration. This means that the tail of the phage acts as a mechanism to deliver the phage DNA into the cell, similar to how a hypodermic needle delivers medication into the body. This allows the phage to take control of the cell's machinery and replicate itself, ultimately leading to the destruction of the host cell.

The shape of a virus is determined by its capsid. The capsid is the protein coat that surrounds the nucleic acid (DNA or RNA) of the virus. It provides protection to the genetic material and helps in the attachment of the virus to host cells. The capsid can have various shapes, such as helical, icosahedral, or complex, depending on the type of virus. The nucleic acid contains the genetic information of the virus, while the envelope and tail are specific features found in certain types of viruses, but they do not determine the overall shape of the virus.

The presence of specific receptor molecules on the host cell is a limiting factor for viral infection. Viruses require specific receptors on the surface of host cells in order to attach and enter the cell. If the host cell lacks the necessary receptors, the virus cannot infect and replicate within the cell. Therefore, the presence or absence of specific receptor molecules on the host cell determines whether or not viral infection can occur.

The host range refers to the groups of organisms that a virus is capable of infecting. Different viruses have different host ranges, meaning they can infect specific species, a few related species, or a wide range of species. The host range is determined by the ability of the virus to recognize and attach to specific receptors on the host's cells. Therefore, the correct answer is "host range."

Lysogenic phages are able to either replicate and cause cell lysis or integrate their DNA into the host DNA. This dual ability allows them to exist in a dormant state within the host cell, known as lysogeny, until certain conditions trigger the phage to transition into the lytic cycle, where it replicates and causes the host cell to lyse. This ability to switch between lysogeny and the lytic cycle is a characteristic feature of lysogenic phages.

A phage that replicates inside the host cell and then lyses its host during its release is referred to as a virulent or lytic phage. This type of phage actively infects and destroys the host cell in order to release its progeny phages. It does not integrate its genetic material into the host genome, unlike a lysogenic phage which establishes a dormant state within the host cell. Therefore, the correct answer is virulent or lytic phage.

During the attachment of phage to E.coli, the phage does not actively seek out bacteria, but rather randomly bumps into them. However, once they come into contact with the bacterial surface, they attach to proteins or carbohydrates present on the surface. This process involves both random collision and specific attachment to the bacterial surface components.

An individual virus particle, also known as a virion, refers to a complete and fully infectious form of a virus that is capable of replicating within a host cell. It contains the genetic material of the virus, either DNA or RNA, surrounded by a protein coat called a capsid. The virion is the infectious unit that can enter a host cell and hijack its machinery to produce more viruses. It is the structural and functional unit of a virus, responsible for infecting and spreading the viral infection.

The correct answer is "coded for by phage DNA AND early proteins". Phage-encoded proteins are synthesized using the genetic information present in the phage DNA. These proteins are produced during the early stages of phage infection and play a crucial role in the replication and assembly of new phage particles. Therefore, they are both coded for by phage DNA and classified as early proteins.

The protein coat of a virus is called a capsid. The capsid not only protects the nucleic acid of the virus but is also involved in recognizing and binding to specific receptors on the host cell. This recognition is crucial for the virus to enter the host cell and initiate infection. Therefore, the correct answer is that the protein coat of a virus is called a capsid, protects the nucleic acid, and is involved in recognition of host cell receptors.

Extrusion is the correct answer because it refers to a method used by viruses to exit the host bacterium without immediately destroying it. Extrusion involves the virus pushing its way out of the host cell, leaving it intact. This allows the virus to continue infecting other cells and spreading the infection. Lysis, on the other hand, refers to the destruction of the host cell when the virus exits. Inversion and excising are not commonly used terms in the context of virus exit methods.

The viral envelope closely resembles the eukaryotic cell membrane because both structures are composed of a lipid bilayer. The viral envelope is derived from the host cell's membrane during the viral replication process. This similarity allows the virus to easily fuse with the host cell membrane and enter the cell. Additionally, the viral envelope may contain viral proteins that mimic host cell proteins, further facilitating viral entry and evasion of the immune system.

All of the choices are correct because most phages that contain single-stranded DNA can undergo extrusion, contain a positive-sense DNA strand, and have their DNA transformed to double-stranded DNA before replication and transcription occur.

DNA is protected from restriction enzymes by being methylated. Methylation is a process where a methyl group is added to the DNA molecule. This modification prevents restriction enzymes from recognizing and cutting the DNA at specific sites. By methylating the DNA, the cell can control which genes are expressed and protect its own DNA from being cleaved by restriction enzymes, which are naturally occurring in bacteria and are used as a defense mechanism against foreign DNA.

The spikes of the envelope of the E. coli T4 phage attach to the host cell receptors. These spikes are protein structures located on the surface of the phage envelope. They play a crucial role in recognizing and binding to specific receptors on the surface of the host cell. This attachment is necessary for the phage to infect the host cell and initiate the process of viral replication.

If the infecting phage lacks some critical pieces of DNA necessary for replication, it is considered defective. This means that the phage is unable to complete its replication cycle and produce new viral particles effectively. The lack of essential DNA components hinders its ability to replicate and infect host cells successfully.

Filamentous phage only infect E.coli that have pili because pili serve as receptors for the phage to attach and enter the bacterial cell. Without pili, the phage cannot bind to the E.coli and therefore cannot infect it. This specificity allows the phage to selectively target and infect E.coli cells with pili, while leaving E.coli lacking pili unaffected.

The correct answer is the nucleic acid. Bacteriophages are viruses that infect bacteria, and they have a unique structure consisting of a protein capsid that encloses their genetic material, which is the nucleic acid. When a bacteriophage infects a host cell, only the nucleic acid of the virus enters through the host cell wall to initiate the replication process. The capsid, which is the protein coat surrounding the nucleic acid, remains outside the host cell.

Once integrated, phage DNA can remain in the prophage state as long as certain phage genes are expressed. This means that specific genes within the phage DNA need to be activated and transcribed into RNA molecules. These expressed genes are responsible for maintaining the phage DNA in the prophage state, preventing it from being excised or entering the lytic cycle. The expression of these genes plays a crucial role in the stability and persistence of the prophage state within the bacterial host.

UV light can activate the lysogenic production of prophage DNA. UV light damages the DNA by causing the formation of thymine dimers, which are abnormal covalent bonds between adjacent thymine bases. This DNA damage triggers the SOS response in the bacterial cell, leading to the activation of the prophage and the subsequent production of viral DNA. The activation of the prophage results in the lytic cycle, where the viral DNA is replicated and new viral particles are produced, ultimately leading to the lysis of the bacterial cell.

The replicative form of nucleic acid in filamentous phages is positive ssRNA. This means that the phage's genetic material is single-stranded RNA with a positive polarity. This type of RNA can directly serve as a template for protein synthesis without the need for transcription. The positive polarity indicates that the RNA can be directly translated into proteins by the host cell's ribosomes.

Bacteria infected with filamentous phages are termed "carrier cells" because they carry and transmit the phages to other bacteria without being lysed or killed. These bacteria act as a reservoir for the phages, allowing them to spread and infect new hosts. The term "carrier" implies that the bacteria are carrying and spreading the phages, rather than being directly affected or harmed by them.

Filamentous phages are a type of bacteriophage that infect bacteria. They are known for their long, filamentous shape. The correct answer is single-stranded DNA because filamentous phages have a genome consisting of a single strand of DNA. This single-stranded DNA is used as a template for replication and protein synthesis within the host cell. Unlike other phages that have double-stranded DNA or RNA genomes, filamentous phages have a unique structure that allows them to replicate and package their genetic material efficiently.

The proper sequence of animal replication in animal cells starts with attachment of the virion, followed by entry of the virion into the cell. After entry, the virion targets specific cellular components and undergoes uncoating, where its outer protein coat is removed. Once uncoated, the virion replicates its genetic material and undergoes maturation. After maturation, the newly formed virions are released from the cell and shed into the environment. Finally, transmission occurs, allowing the virions to infect new cells or hosts.

In this scenario, the correct answer is that bacterial DNA has replaced critical viral DNA in the phage. This means that when the phage invades the bacterial cell, instead of causing lysis (cell rupture), the phage incorporates bacterial DNA into its own genetic material. This replacement of viral DNA with bacterial DNA prevents the phage from carrying out its normal lytic cycle, resulting in the infected cells not being lysed.

The correct answer is identical DNA sequences in both. This is because the integration of phage DNA into the bacterial chromosome requires a specific recognition and recombination process between the phage DNA and the bacterial DNA. If the DNA sequences are not identical or very similar, the integration process cannot occur efficiently. Therefore, the presence of identical DNA sequences in both the phage and the bacterium is necessary for successful integration.

In the replication of phage containing positive sense DNA, the host's enzymes are used to make dsDNA. This means that the host cell's own enzymes are responsible for synthesizing the double-stranded DNA from the positive sense DNA of the phage. This process involves the host's DNA polymerase, which catalyzes the formation of the complementary DNA strand using the positive sense DNA as a template. The resulting dsDNA can then be used for various processes such as gene expression or further replication.