Microbiology Chapter 14 Answers – Flashcards
Unlock all answers in this set
Unlock answersquestion
| Tobacco Mosaic Virus |
answer
| Dimitri Ivanowsky and Martinus Beiherinck studied what virus? |
question
| Foot and Mouth Disease and Yellow Fever |
answer
| Walter Reed studied? |
question
| Bacteriophages |
answer
| Frederick Twort and Felix d'Herelle studied what? |
question
| viruses |
answer
| in 1930's it was discovered nonliving agents composed of nucleic acid and protein, which are called? |
question
| a culture technique using chicken eggs |
answer
| Alice M Woodruff and Ernest W. Goodpasture developed what? |
question
| Viruses |
answer
| tiny infectious agents, small, obligate intracellular parasites, that lack the machinery for generating energy and large molecules, so they need a host cell to replicate, and genome contains either DNA or RNA |
question
| Capsid |
answer
| the protein coat, made up capsomeres |
question
| Nucleocapsid |
answer
| made up of the capsid with its enclosed genome |
question
| spikes |
answer
| help the virus attach to and penetrate the host cell |
question
| naked viruses |
answer
| composed only of a nucleocapsid |
question
| enveloped viruses |
answer
| viruses surrounded by an envelope |
question
| Virion |
answer
| a completely assembled, infectious virus outside its host cell |
question
| Helical Viruses |
answer
| Helical Symmetry |
question
| Icosahedral Viruses |
answer
| Icosahedral Symmetry |
question
| Complex Symmetry |
answer
| Viruses that have both helical and icosahedral symmetry |
question
| host range |
answer
| what organisms the virus can infect, depending on the capsid structure |
question
| tissue tropism |
answer
| viruses infect certain cell or tissue types within the host |
question
| specific receptor |
answer
| the virus needs this in order to invade the host cell |
question
| Viruses |
answer
| nomenclature and classification do not use conventional taxonomic groups |
question
| a classification system |
answer
| The International Committee on Taxonomy of Viruses (ICTV) is developing this |
question
| DNA Viruses |
answer
| contain single- or double- stranded DNA genomes |
question
| RNA Viruses |
answer
| contain single- or double-stranded RNA genomes |
question
| + Strand RNA Viruses |
answer
| this virus has mRNA genomes |
question
| - Strand RNA Viruses |
answer
| these viruses have RNA strands that would be complementary to mRNA |
question
| Retroviruses |
answer
| replicate indirectly through a DNA intermediate using an reverse transcriptase enzyme |
question
| T-even group bacteriophages |
answer
| Virulent Viruses that carry out a lytic cycle of infectionin prokaryotes |
question
| phage nucleic acid |
answer
| contains only a few of the genes needed for viral synthesis and replication |
question
| 1. Attachment: Viral Replication |
answer
| occurs when a phage's tail fibers match with a receptor site on the bacterium's cell wall |
question
| 2. Penetration: Viral Replication |
answer
| occurs when the phage tail releases lysozme to dissolve a portion of the cell wall. Phage DNA is injected into the bacterial cytoplasm |
question
| 3. Biosynthesis: Viral Replication |
answer
| the production of new phage genomes and capsid parts |
question
| 4. Maturation: Viral Replication |
answer
| the assembly of viral parts into complete virus particles |
question
| 5. Release Viral Reproduction |
answer
| the exit of virions from the bacterium, it is also called the lysis stage when the cell is ruptured |
question
| Temperate Phages |
answer
| do not lyse the host, they insert their DNA into the bacterial chromosome as a prophage (lysogenic cycle) |
question
| 1. Attachment Animal Viral Replication |
answer
| host plasma membrane via spikes on the capsid or envelope |
question
| 2. Penetration Animal Viral Replication |
answer
| Since receptor sites vary from person to person, some people are more susceptible to a certain virus than others |
question
| Animal Viruses |
answer
| usually taken into the cytoplasm as intact nucleocapsids |
question
| uncoating |
answer
| the separation of the capsid from the genome |
question
| 5. Release Animal Viral Replication |
answer
| After the new viruses are assembled, envelop proteins are incorporated into a cellular membrane, the virus buds, taking the membrane part with it as an enzyme |
question
| Provirus |
answer
| Some DNA viruses and retroviruses insert their genome into the host chromosome |
question
| Reverse Transcriptase |
answer
| Retroviruses use this to transcribe their RNA to DNA |
question
| provirus |
answer
| encodes a repressor protein that prevents activation of the viral genes necessary for replication |
question
| Latent proviruses |
answer
| immune to the host body's defeneses, they are propagated each time the cell's chromosome is reproduced |
question
| River's Postulates |
answer
| filtrates of infectious materials shown not to contain bacterial or other cultivatable organisms must produce the disease or its counterpart, filtrates must produce specific antibodies |
question
| Cytology |
answer
| uses light microscopy to examine cells for cytopathic effects (CPEs) of viral infection |
question
| Cultivation and Detection of Viruses |
answer
| Most often uses cells in culture |
question
| primary cell culture |
answer
| cells form a monolayer in a culture dish |
question
| monolayer |
answer
| the type of cell culture depends on the virus to be cultivated |
question
| plaques |
answer
| Viruses can be detected by the formation of these, a clear zone within the monolayer |
question
| Viruses |
answer
| can be grown in fertilized eggs |
question
| cancer |
answer
| an uncontrolled growth and spread of cells |
question
| Tumor |
answer
| clone of abonormal cells |
question
| Benign Tumor |
answer
| Normally, the body surrounds a tumor with a capsules of connective tissue |
question
| Malignant Tumor |
answer
| Tumor cells can break free from the capsule and spread to other tissues of the body (metastasis) |
question
| Viruses |
answer
| responsible for up to 20% of human tumors |
question
| carcinogens |
answer
| 60-90% of human cancers are associated with these |
question
| oncogenic viruses |
answer
| transform infected cells by these |
question
| Epistein Barr virus |
answer
| linked to Burkitt Lymphoma, a tumor of the jaw |
question
| Human Papilloma Virus (HPV) |
answer
| associated with cervical cancer |
question
| Oncogene Theory |
answer
| suggests that protooncogenes normally reside in the chromosomal DNA of a cell |
question
| Oncogenes |
answer
| these can be transformed by radiation, chemical carcinogens, DNA damage, viruses |
question
| Virus |
answer
| infects its DNA as a provirus into a cell's chromosome next to a protooncogene |
question
| Virus Replication |
answer
| when triggered, the provirus replicates its DNA as well as few adjacent host genes |
question
| V-Oncogenes |
answer
| protooncogenes captured in the viral genome, when the oncogenic viruses infect another cell, this is under the virus's control, not the cell's control, they can code for growth factors, stimulating uncontrolled cell proliferation |
question
| Emerging Viruses |
answer
| usually arise through natural phenomena, may spread to new populatiosn or may expand host range |
question
| Genetic Recombination |
answer
| may lead to "new" viruses |
question
| Mutation |
answer
| occasionally be advantageous and create a new virus or stain a virus |
question
| Regressive Evolution Hypothesis |
answer
| Viruses degenerate life-forms |
question
| Cellular Origins Hypothesis |
answer
| Viruses are derived from subcellular components and macromolecules that escaped from cell walls and replicated inside hosts |
question
| Independent Entities Hypothesis |
answer
| Viruses coevolved with cellular organisms from a self-replicating moelcule present on primitive Earth |
question
| Viroids |
answer
| infectious RNA particles, tiny fragments of RNA that cause diseases in crop plants, replication cycle and disease causation process for these are not understood, one hypothesis suggests introns |
question
| Prion |
answer
| infectious proteins |
question
| Transmissible Spongiform Ecephalopathies (TSEs) |
answer
| can occur in humans and other animals, (e.g. mad cow disease), are neurologic degenerative diseases that can be transmitted within or between species |
question
| Protein Only Hypothesis |
answer
| predicts that prions are composed only of protein and contain no nucleic acids |
question
| Abnormal Prions |
answer
| Has a different shape than normal prions, causes TSEs, may spread TSEs when infectious prions bind to normal prions, causing normal prions to change shape and become one of them, do not trigger an immune response |
question
| Death of Host |
answer
| occurs from nerve cell death leading to sponge-like holes in brain tissue. Symptoms include, dementia, weakened muscles, and loss of balance , resulting from insoluble aggregates of abnormal prions in the brain |
question
| Variant CJD (Creutzfeldt-Jakob Disease) |
answer
| the human form of TSE is this |
