Micro Study Guide 3

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The envelope is not associated with every virus. While many viruses do have an envelope, which is a lipid membrane derived from the host cell, not all viruses possess this structure. Some viruses, known as naked viruses, lack an envelope and instead have a capsid, which is a protein coat that protects the nucleic acid genome. Therefore, the presence of an envelope is not a universal characteristic of all viruses.

Latent viruses cause infection resulting in alternating periods of activity with symptoms and inactivity without symptoms. These viruses can remain dormant in the host's cells for extended periods of time, without causing any noticeable symptoms. However, they can become active and cause symptoms during certain conditions or when the host's immune system is weakened. This ability to alternate between periods of activity and inactivity is what characterizes latent viruses.

Viruses cannot be seen with a light microscope because they are much smaller than the wavelength of visible light. Viruses are acellular and do not have the characteristics of living organisms, such as being procaryotic or undergoing binary fission. They also do not contain ribosomes. Additionally, viruses cannot be grown on nutrient agar because they require a host cell to replicate.

All of the choices are correct because viruses can infect a wide range of host cells, including humans and other animals, plants and fungi, bacteria, protozoa, and algae. Viruses have evolved to be able to invade and replicate within specific host cells, often causing diseases or other effects in the process. Therefore, all of the options listed are valid examples of host cells that viruses can infect.

Capsomers are protein subunits that make up the capsid, the protein coat that surrounds the genetic material of a virus. These protein subunits come together to form a symmetrical structure, which provides protection to the viral genome. The capsid is crucial for the virus's ability to infect host cells and replicate. Therefore, the correct answer is protein.

Classification of viruses into families involves determining the type of nucleic acid, type of capsid, presence of an envelope, and nucleic acid strand number. However, the classification does not involve determining biochemical reactions. Biochemical reactions are not used as a criterion for categorizing viruses into families.

Helminthes, which are parasitic worms, have reproductive organs as their most developed organs. This means that their reproductive system is highly developed compared to other organs in their body. They are not all parasites, although some of them are. Their eggs and larvae are vulnerable to heat, meaning that high temperatures can kill them. Tapeworms and pinworms are two examples of helminthes. However, the statement that they generally make only a few eggs per day is incorrect. Helminthes can produce a large number of eggs per day, depending on the species.

When a virus enters a lysogenic phase, it means that the virus is integrated into the DNA of the host cell. In this phase, the viral genetic material becomes a part of the host cell's DNA and is replicated along with it during cell division. This allows the virus to remain dormant within the host cell, without causing immediate harm or replicating itself. However, under certain conditions, such as stress or environmental triggers, the virus can enter the lytic phase where it becomes active, starts replicating, and eventually bursts out of the host cell, leading to the release of new viral particles.

Viroids are infectious naked strands of RNA that are smaller than viruses. They lack a protein coat and are composed solely of RNA. Viroids are known to cause diseases in plants, interfering with their growth and development. Unlike viruses, viroids do not encode any proteins and rely on host enzymes for replication. Therefore, viroids are the correct answer to the question.

Virus capsids are the protein coats that surround the genetic material of a virus. These capsids are composed of repeating subunits called capsomeres. Each capsomere is made up of one or more viral proteins. The capsomeres come together to form the outer shell of the virus, providing protection to the genetic material inside. Therefore, capsomeres are the correct subunits that make up virus capsids.

Fungi are classified as Fungi Imperfecti, or Deuteromycota, based on whether they lack a sexual state. Unlike other fungi, which have a defined sexual reproduction process, fungi in this classification reproduce only through asexual means. This means that they do not produce spores or structures involved in sexual reproduction. Instead, they rely on methods such as fragmentation or budding to reproduce. This classification is used for fungi that have not yet been observed to have a sexual stage in their life cycle.

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The host range of a virus refers to the range of species or cell types that the virus can infect. The type of host cell receptors on the cell membrane plays a crucial role in determining the host range of a virus. Viruses typically bind to specific receptors on the surface of host cells in order to gain entry and initiate infection. If the virus cannot recognize and bind to the specific receptors present on the cell membrane of a particular host, it will be unable to infect that host. Therefore, the type of host cell receptors on the cell membrane is a key factor that limits the host range of a virus.

Herpesviridae represents a virus family name. It is a taxonomic classification used to group viruses that belong to the Herpesviridae family. This family includes various viruses, including the Herpes simplex virus, which is a specific member of the Herpesviridae family. Other options listed, such as Picornavirus, Enterovirus, and Hepatitis B virus, represent specific virus species or types rather than virus family names.

Creutzfeld-Jacob disease is a spongiform encephalopathy of humans. This means that it is a degenerative neurological disorder characterized by the accumulation of abnormal proteins in the brain, leading to the death of brain cells. It is not caused by a chronic latent virus, an oncogenic virus, or a viroid. It is also not the same as "mad cow disease," which is a similar spongiform encephalopathy but affects cows rather than humans.

Viruses are known to have a geometric capsid, which is a protein coat that surrounds their genetic material. They can also cause both mild and fatal diseases, depending on the specific virus and host. Additionally, viruses can be crystallized, meaning their structure can be converted into a solid form. However, viruses do not have a viscous fluid inside their capsids. Instead, their capsids contain the genetic material of the virus, such as DNA or RNA. Therefore, the correct answer is that viruses do not have a viscous fluid inside their capsids.

Tail fibers are structures used by bacteriophages to attach to host cell receptors. Bacteriophages are viruses that infect bacteria, and they use their tail fibers to recognize and bind to specific receptors on the surface of the host cell. This attachment is necessary for the virus to inject its nucleic acid (genetic material) into the host cell and initiate the infection process. The tail fibers act like a key that fits into a specific lock, allowing the virus to gain entry into the host cell.

All of the choices are correct because each option listed represents a different type of cytopathic effect. Inclusions in the nucleus and inclusions in the cytoplasm refer to the presence of abnormal substances within these cellular compartments. Multinucleated giant cells are formed when multiple cells fuse together, resulting in a larger, multinucleated cell. Lastly, cells rounding up is a characteristic cytopathic effect where cells lose their normal shape and become rounded. Therefore, all of these options accurately describe different types of cytopathic effects.

Viruses do not belong to any of the five traditional kingdoms (Protista, Fungi, Plantae, Animalia, and Monera). They are considered to be non-living entities and exist in a gray area between living and non-living organisms. They lack the necessary cellular machinery to carry out metabolic processes and reproduce on their own. Therefore, they are not classified within any kingdom.

The core of every virus particle can contain either DNA or RNA. Viruses are classified based on the type of genetic material they possess. Some viruses have DNA as their genetic material, while others have RNA. The genetic material is enclosed within a protein coat called capsomers. Enzymes may also be present in the virus particle, but they are not always a part of the core. Therefore, the correct answer is either DNA or RNA.

Viruses do not possess metabolism, which is the set of chemical reactions that occur within an organism to maintain life. Unlike living organisms, viruses cannot independently carry out metabolic processes such as respiration, growth, or reproduction. Instead, viruses rely on host cells to provide the necessary machinery and resources for their replication. This is why viruses are often considered as non-living entities, as they lack the ability to perform essential life processes on their own.

The correct answer is "capsid" because the term "capsid" refers to the protein coat that surrounds the genetic material of a virus. It is responsible for protecting the genetic material and giving the virus its shape. The other options, such as spike, capsomere, envelope, and core, are not specifically related to the shape of a virus, but rather different components or structures associated with it.

Helminths are parasitic worms that belong to the phylum Platyhelminthes (flatworms) or Nematoda (roundworms). Pinworms, flukes, roundworms, and tapeworms are all examples of helminths. However, trypanosomes are not helminths. Trypanosomes are single-celled protozoan parasites that belong to the genus Trypanosoma and cause diseases such as African sleeping sickness and Chagas disease.

Chitin is a chemical component of the cell walls of fungi. Fungi have cell walls made of chitin, which is a tough and flexible polysaccharide. Chitin provides structural support and protection to fungal cells. It is also found in the exoskeletons of arthropods, such as insects and crustaceans. Chitin is not present in the cell walls of protozoa, algae, or bacteria. Therefore, the correct answer is fungi.

Blooms of certain dinoflagellates are associated with paralytic shellfish poisoning, red tides, and Pfiesteria piscicida. Euglenids, on the other hand, are a different group of single-celled organisms and are not typically associated with these harmful algal blooms.

Larvae and eggs are developmental forms commonly found in helminths, which are parasitic worms. Protozoa are single-celled organisms, algae are photosynthetic organisms, and fungi are multicellular organisms that reproduce through spores. Therefore, the correct answer is helminths.

The correct answer is Ascomycota because this group of fungi is characterized by having asexual conidia, sexual spores within a sac (called an ascus), and septate hyphae. Ascomycota includes a wide range of fungi, including yeasts, molds, and truffles. This group is known for their ability to produce ascospores, which are sexual spores formed inside the ascus.

Fungi do not perform photosynthesis, which is the process by which organisms convert sunlight into energy. Unlike plants, fungi do not contain chlorophyll and cannot produce their own food through photosynthesis. Instead, they obtain nutrients by breaking down organic matter in their environment. This characteristic, along with the presence of cell walls, the ability to use a wide variety of nutrients, and the inclusion of both single-celled and filamentous forms, are all typical characteristics of fungi.

Cilia are found in protozoa, which are single-celled organisms that have hair-like structures called cilia on their surface. These cilia help in various functions such as movement, feeding, and sensory perception. Protozoa are a diverse group of organisms that can be found in various habitats including freshwater, marine environments, and soil. They play important roles in ecosystems and can have both beneficial and harmful effects on other organisms.

The nucleocapsid refers to the combination of the nucleic acid (genetic material) of the virus along with the capsid (protein coat). This means that the correct answer is "the nucleic acid along with the capsid". The other options either do not include the capsid or include additional components like the envelope.

All of the choices are correct. During viral multiplication, uncoating of viral nucleic acid can occur in various ways depending on the type of virus. In bacteriophage multiplication, uncoating does not occur as bacteriophages inject their nucleic acid directly into the host cell. Enzymatic destruction of the capsid is a common mechanism of uncoating in many viruses. Uncoating can occur during penetration, as the virus enters the host cell and sheds its capsid. It can also occur before replication, as the viral nucleic acid is released and becomes accessible for replication.

The correct sequence of events in viral multiplication starts with adsorption, where the virus attaches to the host cell. This is followed by penetration, where the virus enters the host cell. Replication then occurs, where the viral genetic material is copied and new viral components are synthesized. Maturation is the next step, where the newly formed viral components are assembled into complete viruses. Finally, assembly takes place, where the individual viral components come together to form mature viruses. The last step is release, where the mature viruses are released from the host cell to infect other cells.

Protists are a diverse group of eukaryotic microorganisms that include algae and protozoa. Algae are photosynthetic organisms that can range from single-celled to multicellular forms, while protozoa are single-celled heterotrophic organisms that can move and capture their food. Therefore, the statement "algae and protozoa" is correct because both of these groups are included in the category of protists.

Virus envelopes are not located between the capsid and nucleic acid. The envelope is a membrane-like structure that surrounds some viruses, derived from the host cell membrane or nuclear membrane. It contains special virus proteins, which help the virus particle attach to host cells. Therefore, the correct answer is that virus envelopes are not located between the capsid and nucleic acid.

When a eukaryotic cell is not undergoing mitosis, the DNA and its associated proteins are in a less condensed form known as chromatin. This allows for easier access and transcription of the genetic information stored in the DNA. The chromatin appears as a visible thread-like mass within the nucleus of the cell. During mitosis, the chromatin condenses further to form distinct chromosomes.

Prions are infectious protein particles that can cause diseases in animals and humans. Unlike viruses, bacteria, or other microorganisms, prions do not contain genetic material such as DNA or RNA. Instead, they are composed of misfolded proteins that can induce normal proteins to adopt the same abnormal conformation. This misfolding process can lead to the accumulation of prions in the brain, causing neurodegenerative disorders such as Creutzfeldt-Jakob disease, mad cow disease, and scrapie. Therefore, prions are the correct answer for the question.

Mastigophora is the correct answer because this group of protozoa is characterized by the presence of flagella. Flagella are whip-like structures that are used for movement. Sarcodina is a group of protozoa that move using pseudopods, Ciliophora move using cilia, and Apicomplexa do not have flagella at all. Therefore, Mastigophora is the only choice that accurately describes the group of protozoa with flagella.

The correct answer is "use them to expel excess water from the cell." Contractile vacuoles are structures found in some protists that help regulate water balance within the cell. These vacuoles collect and expel excess water, preventing the cell from bursting or becoming too diluted. This is an important adaptation for protists that live in environments with high water concentrations or experience osmotic stress. The other options are incorrect because not all protists are algae, not all protists live in salty seawater, and not all protists use contractile vacuoles for motility.

Fungal spores are used to identify fungi because they have unique characteristics that can help distinguish different species. These spores can have distinct shapes, sizes, colors, and patterns, which can be observed and analyzed under a microscope. By studying these characteristics, scientists can identify and classify different types of fungi. Fungal spores are also important in the reproduction and dispersal of fungi, as they can be carried by wind, water, or other organisms to new locations. Therefore, their presence and characteristics can provide valuable information for fungal identification.

Sporangiospores are the correct answer because they are produced within a sac-like structure called a sporangium. This structure protects the spores until they are ready to be released. Chlamydospores, blastospores, arthrospores, and zygospores are all different types of spores, but they are not produced within a sac.

All of the choices are correct because eukaryotic cells, unlike prokaryotic cells, have a nucleus, mitochondria, endoplasmic reticulum, and lysosomes. The nucleus contains the cell's DNA and is responsible for controlling cellular activities. Mitochondria are the powerhouses of the cell, producing energy through cellular respiration. Endoplasmic reticulum is involved in protein synthesis and lipid metabolism. Lysosomes contain enzymes that break down waste materials and cellular debris. These organelles are unique to eukaryotic cells and are not found in prokaryotic cells.