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Chapter 14
Virology
105
Microbiology
Undergraduate 1
11/17/2010

Additional Microbiology Flashcards

 


 

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Term
Virosphere
Definition
refers to all places where viruses are found or interact with their hosts
Term
Tobacco Mosaic Disease
Definition
Ivanowsky 1892; A viral disease causing tobacco leaves to shrivel and assume a mosaic appearance
→ filtered the crushed leaves of a diseased plant and found the clear liquid passing through the filter contained the infectious agent.
Term
Foot and Mouth Disease
Definition
A highly contagious viral disease of cloven-hoofed animals like sheep, cattle, and deer
Term
Yellow Fever
Definition
A mosquito-borne viral disease of human liver and blood
Term
Bacteriophage/Phage
Definition
A virus that infects and replicates within bacterial cells
Term
Virus
Definition
An infectious agent consisting of DNA or RNA and surrounded by a protein sheath; in some cases, a membranous envelope surrounds the coat
Term
Virus
Definition
small, obligate intracellular particles, most can be seen with an electron microscope, and must infect and take over a host cell in order to replicate because they lack the chemical machinery for generating energy and synthesizing large molecules
Term
Virus
Definition
no organelles, no cytoplasm, no cell nucleus or nucleoid
→ Composed of a nucleic acid core and a surrounding coat of protein
Term
Genome
Definition
The complete set of genes in a virus or an organism
→ contain either DNA or RNA (single or double stranded)
→ usually folded or coiled, to keep small shape
Term
Capsid
Definition
The protein coat that encloses the genome of a virus; gives shape or symmetry to the virus; two parts the capsomere and nucleocapsid; also provides protective covering for the viral genome
Term
Capsomere
Definition
Any of the protein subunits of a capsid (the organization yields the viral symmetery)
Term
Nucleocapsid
Definition
The combination of genome and capsid of a virus
Term
Spikes
Definition
A protein projecting from the viral envelope or capsid that aids in attachment and penetration of a host cell
→ help attach the virus to the host cell and facilitate penetration of the cell
Term
naked virus
Definition
Viruses composed soley of a nucleocapsid
Term
Envelope
Definition
The flexible membrane of protein and lipid that surrounds many types of viruses
→ composed of lipids and proteins, similar to the host cell membrane, loose fitting structure over the nucleocapsid, many contain spikes projecting from the envelope
Term
enveloped viruses
Definition
Viruses enclosed in an envelope
Term
Virion
Definition
A completely assembled virus outside its host cell
Term
Helical
Definition
One form of symmetry found in some viral capsids; helix tightly wound coil resembling a corkscrew or spring
Term
Icosahedral
Definition
referring to a symmetrical figure composed of 20 triangular faces and 12 points; one of the forms of symmetry found in some viral capsids (e.g. herpes simplex, polioviruses)
Term
Complex
Definition
referring to one form of symmetry found in some viral capsid; icosahedral + helical;
Term
Host Range
Definition
The variety of species that a disease-causing microorganism can infect; refers to what organisms (hosts) the virus can infect and it is based on a virus’ capsid structure, most are very narrow
Term
Tissue Tropism
Definition
refers to the specific tissues within a host that a virus infects (tissue attraction)
Term
DNA Viruses
Definition
→ either contain single stranded (ss) or double-stranded (ds)
→ either linear or segmented
→ replicated by direct DNA-to-DNA copying using DNA polymerase, which requires most DNA viruses to replicate in the host cell’s nucleus
* exception = poxviruses that replicate in the host cytoplasm, which means these viruses must carry the genes for their own DNA polymerase *
Term
RNA Viruses
Definition
→ either ssRNA or dsRNA genomes replicated by direct RNA-to-RNA copying
→ either linear or segmented
Term
Positive Strand (+ Strand)
Definition
referring to the RNA viruses whose genome consists of mRNA molecule; single-stranded, e.g. picornaviruses and coronaviruses
Term
Negative Strand (- Strand)
Definition
referring to those RNA viruses whose genome cannot be directly transcribed into protein; RNA genomes consisting of RNA strands that would be complementary to a mRNA; single stranded, e.g. orthomyxoviruses and paramyxoviruses
Term
Retroviruses
Definition
replicate indirectly through DNA intermediate (RNA-to-DNA-to-RNA) Each virion contains two copies of + strand RNA. During the infection process, a DNA intermediate will be formed using a reverse transcriptase enzyme carried within the virion
Term
Reverse Transcriptase
Definition
An enzyme that copies single-stranded RNA into double stranded DNA
-RNA virus genomes are smaller than DNA virus genomes, and depend more heavily on host cell proteins and enzymes for replication
Term
Virus
Definition
invades a living host cell, hijacks the metabolism of the cell to produce copies of itself, and often destroys the host cell when new virions are released
Term
Bacteriophages of the T-even group (T for type)
Definition
they are large, complex, naked DNA virions with the characteristic head and tail of bacteriophage, contain tail fibers, which function like spikes on an animal virus and identify what bacterial species the phage will be able to infect; only carries a few of the many genes needed for viral synthesis and replication
Term
Virulent Viruses
Definition
T-even phages, referring to a virus that can be extremely damaging when in the host
Term
Lytic Cycle
Definition
A process by which a bacterial virus replicates within a host cell and ultimately destroys the host cell; Virulent Viruses
Term
Attachment Bacterial Viral Infection
Definition
the phage and bacterial cells collide randomly, and if the tail fibers match with the receptor sites on the cell wall then this stage occurs. It consist of a weak chemical bond and in some cases, bacterial flagellum or pilus contain the receptor site
Term
Penetration Bacterial VIral Infection
Definition
tail releases lyzosome, which dissolves part of the bacterial cell wall, the tail sheath contracts and the tail drives through the cell wall and when it reaches the cell membrane, DNA is ejected into the cytoplasm
Term
Biosynthesis Bacterial Viral Infection
Definition
production of new phage genomes and capsid parts begin. The phage gene codes disrupt the host chromosome, so the phage DNA can use the bacterial nucleotides and enzymes to synthesize copies of its genome. Once mRNA transcribes the phage DNA, phage enzymes and capsid proteins begins. Ribosomes, amino acids, and enzymes are included in this process
Term
Maturation Bacterial Viral Infection
Definition
phage parts assemble into complete virus particles, enzymes encoded by viral genes guide the assembly step-by-step, in the host cytoplasm phage heads and tail are assembled, another area heads are packaged with DNA, and tails are attached to the heads
Term
Release Bacterial Viral Infection
Definition
mature phages burst from the ruptured bacterial shell, and are set free to infect more cell
Term
Lysogenic Cycle
Definition
The events of a bacterial virus infection that result in the integration of its DNA into the bacterial chromosome
Term
Prophage
Definition
The viral DNA of a bacterial virus that is inserted into the bacterial DNA and is passed on from one generation to the next during binary fission
Term
Temperate Phages
Definition
Referring to a bacterial virus that enters a bacterial cell and then the viral DNA integrates into the bacterial cell’s chromosomes
Term
Productive Infection
Definition
the active assembly and maturation of viruses in an animal cell
Term
Phage
Definition
the bacterial cells survive the infection and continue to grow and divide normally, it undergoes DNA replication and binary fission, the ____ is copied and vertically transferred to chromosome, as cells divide, each daughter cell is “infected” containing the viral genome as a ____; the binary fissions can occur for an undefined time period, but at some point the cell becomes “stressed” (e.g. lack of nutrient, presence of noxious chemicals) and this triggers the ____ to excise itself from the bacterial chromosomes and switch to a lytic cycle, releasing the bacterial cells as new phages
Term
Attachment Animal Viruses
Definition
Animal Viruses infect host cells by binding to receptors on the host cell’s plasma membrane by the spikes on the surface of the capsid or envelope, which determines the host range for a virus
Term
Penetration Animal Viruses
Definition
Some viruses (adenoviruses like HIV) need a second receptor called the co-receptor for viral penetration into the cytoplasm, where they are taken into the cytoplasm as full nucleocapsids. Viruses like HIV the viral envelope fuses with the plasma membrane and releases the nucleocapsid into the cytoplasm
Term
Coreceptor
Definition
the second receptor site where viral penetration into the cytoplasm takes place
Term
Penetration Animal Viruses
Definition
Other viruses like adenoviruses and influenzavirus, the virion is taken into the cell by endocytosis. At the attachment site, the cell enfolds the virion within a vacuole and brings it into the cytoplasm, where it breaks down in the vacuole and releases the nucleocapsid or the genome into the cytoplasm
Term
Uncoating
Definition
referring to the loss of a the viral capsid inside an infected eukaryotic cell
Term
Biosynthesis and Maturation Animal Viruses
Definition
DNA of a DNA virus supplies the genetic codes for enzymes that synthesize viral parts from available building blocks; Most DNA viruses have the DNA genome synthesized in the host cell nucleus and capsid proteins are produced in the cytoplasm, the proteins are transported to the nucleus and join with the nuleic acid molecules for maturation (e.g Adenoviruses and herpesvirus)
Term
Biosynthesis and Maturation Animal Viruses
Definition
RNA viruses the RNA immediately begins supplying the codes for protein synthesis as genome replication occurs because +ssRNA viruses act as a mRNA
Term
Biosynthesis and Maturation of Animal Viruses
Definition
ssRNA viruses (e.g. influenzavirus) use their RNA as a template to synthesis a complementary (+) strand of RNA. An RNA dependent RNA polymerase is present in the virus to synthesize the (+) strand. The synthesized +ssRNA then is used as a mRNA molecule for protein synthesis as weel as a template to form –ssRNA genome
Term
Biosynthesis and Maturation of Animal Viruses
Definition
The final steps of maturation include the acquisition of an envelope, where the envelope proteins (spikes) are synthesized and depending on the virus, incorporated into a nuclear or cytoplasmic membrane or the plasma membrane
Term
Release Animal viruses
Definition
final stage where enveloped viruses either 1.) push through the plasma membrane forcing a portion of the membrane ahead of and around the virion resulting in an envelope 2.) a membrane-enclosed virus fuses with the plasma membrane releasing the virion (e.g. herpevirus) This is called budding need not necessarily kill the cell during release, but they leave the cell when the cell membrane ruptures
Term
Budding
Definition
The controlled release of virus particles from an infected animal cell
Term
Latent Infection
Definition
A viral infection where the viral DNA remains “dormant” within a host chromosome
→ e.g. herpes simplex virus-1
Term
Latent Infection
Definition
DNA virus can generate a productive or latent infection, In an infected sensory neuron, the virus under goes latency as the viral dsDNA enters the neuron’s cell nucleus and circularizes. No viral particles are produced for months or years until some stress reactivates the viral dsDNA and a productive infection is produced
Term
Reverse Transcriptase
Definition
An enzyme that synthesizes a DNA molecule from the code supplied by an RNA molecule
Term
Provirus
Definition
the viral DNA that has integrated into a eukaryotic host chromosome and is then passed on from one generation to the next through cell division
Term
Proviruses
Definition
The dsDNA eneters the host cell nucleus and becomes integrated into the DNA of one chromosome, forming a _____ (e.g. retroviruses like HIV) which is then replicated each time the host cell divides along with the host genome, and is present in all progeny cells. _____ are protected from attack by antiretroviral drugs, but at any time can be reactivated and a productive infection occurs
Term
Koplik Spots
Definition
red patches with white central lesions that form on the gums and walls of the pharynx during the early stages of measles
Term
River Postulates
Definition
A set of procedures by which a specific virus can be associated with a specific disease
Term
River Postulates
Definition
filtrates the infectious material isolated from the diseased host shown not to contain bacterial or other cultivatable organism must produce the same disease as found in the host or the filtrates must produce specific antibodies in appropriate animals
Term
Cytopathic Effect (CPE)
Definition
Visible effect that can be seen in a virus infected host cell, which can be observed using a light microscope when examining cells obtained from body tissues or fluids
Term
Viruses
Definition
change in cell structure often
→ can have large number of lymphocytes with “foamy looking” highly vacuolated cytoplasm in infectious mononucleosis
Term
Syncytia
Definition
A giant tissue cell formed by the fusion of cells infected with respiratory syncytial viruses (paramyxoviruses)
Term
Negri Bodies
Definition
A cytoplasmic inclusion that occurs in brain cells infected with rabies vaccine
Term
Way to Culture Viruses
Definition
inoculate them into fertilized chicken eggs by drilling a hole in the shell and a suspension of viral material is introduced
common with influenza viruses, which is origin of vaccine production
Term
Primary Cell Culture
Definition
Animal cells separated from tissue and grown in cell culture; prepare the culture, animal cells are separated from a tissue with enzymes and suspended in a solution of nutrients, growth factors, pH buffers, and salts
→ the cells adhere to the bottom of a plastic dish or well, and reproduce to form a monolayer
Term
Monolayer
Definition
a single layer of cultured cells
Term
Cell Line
Definition
A group of identical cells in culture and derived from a single cell; The different cell types in a primary cell culture can be separated enzymatically and isolated as a single cell type by this, and depends on the virus species to be cultivated in the monolayer and then viruses are introduced into culture
Term
Viruses
Definition
can be detected by the formation of plaques in a monolayer
Term
Plaque
Definition
A clear area on a lawn of bacterial cells where viruses have destroyed the bacterial cells; “bacterial lawn” or monolayer in animal cells; Viruses infect and replicate in the cells, and destroy the bacterial cells
Term
Phage Typing
Definition
A procedure of using specific bacterial viruses to identify a particular strain of a bacterial species
Term
Cancer
Definition
results from the uncontrolled reproduction (mitosis) of a single cell and the cells form a cluster of cells
Term
Tumor
Definition
An abnormal uncontrolled growth of cells that has no physiological function
Term
Benign
Definition
referring to a tumor that usually is not life threatening or likely to spread to another part of the body
Term
Metastasize
Definition
referring to a tumor that spreads from the site of origin to other tissues in the body
Term
Malignant
Definition
referring to a tumor that invades the tissue around it and may spread to other parts of the body
Term
Cancer
Definition
A disease characterized by the radiating spread of malignant cells that reproduce at an uncontrolled rate
Term
Carcinogen
Definition
Any physical or chemical substance that causes tumor formation
Term
Chemical Carcinogen
Definition
hydrocarbons found in cigarettes smoke, asbestos, nickel, certain pestisides, and dyes, environmental pollutants in high amounts
Term
Physical Carcinogen
Definition
UV light and X rays
Term
Sacroma
Definition
A malignant tumor that begins growing in connective tissue such as muscle, bone, fat, or cartilage
Term
Burkitt lymphoma
Definition
A tumor of the jaw triggered by the Epstein-Barr virus
Term
B Lymphocytes
Definition
A white blood cell that matures into memory cells and plasma cells that secrete antibody
Term
Cervical Cancer
Definition
Cancer of the cervix caused by several papillomaviruses
Term
PAP Smear
Definition
A test to detect cancerous or precancerous cells of the cervix, allowing for early diagnosis of cancer
Term
Oncogenes
Definition
A segement of DNA that can induce uncontrolled growth of a cell if permitted to function (genetic basis of cancer)
Term
Proto-Oncogenes
Definition
A region of DNA in the chromosome of human cells; they are altered by carcinogens into oncogenes that transform cells; important in cell metabolism and growth regulation; influences cellular growth
Term
V-Oncogenes
Definition
proto-oncogenes “captured” in the viral genome in the DNA; influences cellular growth
Term
Emerging Infectious Disease
Definition
A new disease or changing disease that is seen for the first time (e.g. West Nile Virus, Hantavirus, HIV)
Term
Genetic Recombination
Definition
The process of bring together different segments of DNA; allows the reassortment of genome segments (e.g swine flu)
Term
Mutation
Definition
A permanent alteration of a DNA sequence
→ When a single nucleotide is altered (point mutation) in an RNA virus genome in the host cytoplasm, because there is no way to “proofread” or correct the mistake during replication
Term
Viruses
Definition
They need to find a suitable host to replicate and spread in
• Sometimes they make a species jump (e.g. from rodents to humans in South American hemorrhagic fevers); An increase in the size of the animal host population carrying a viral disease also can “explode” as an emerging viral disease
Term
Regressive Evolution Hypothesis
Definition
Viruses are degenerate life-forms, they are derived from intracellular parasites that have lost many functions other organisms possess and have retained only those genes essential for their parasitic way of life
Term
Cellular Origin Hypothesis
Definition
Viruses are derived from fragments of cellular genetic material and functional assemblies of macromolecules that have escaped their origins inside cells by being able to replicate autonomously in host
Term
Independent Entities Hypothesis
Definition
Viruses coevolved with cellular organisms from the self-replicating molecules believed to have existed in the primitive prebiotic earth
Term
Virus Like Agents
Definition
subviral particles that are disease agents
Term
Viroids
Definition
An infectious RNA segment associated with certain plant diseases
Term
Dementia
Definition
A loss of memory
Term
Transmissible Spongiform encephalopathies (TSEs)
Definition
A group of progressive conditions that affect the brain and nervous system (e.g. Mad Cow Disease, Creutzfeldt-Jakob disease, scrapie in sheep and goats, wasting disease in elk and deer)
Term
Transmissible Spongiform Encephalopathies (TSEs)
Definition
animal disease can be transmitted to other animals of the same species and possible to other animal species, including humans, and the disease causes the formation of “sponge like” holes in brain tissue
Term
Prion
Definition
An infectious, self-replicating protein involved in human and animal diseases of the brain
→ PrP is a coding gene expressed in the brain
Term
Protein Only Hypothesis
Definition
The idea that prions are composed solely of protein and contain no nucleic acid; two types of prion proteins: 1.) normal cellular prions (PrPc) found on the surfaces of brain cells 2.) abnormal, misfolded prions (PrPSC) have a different shpe, and are suspected infectious agents of neurological diseases (TSEs) like mad cow disease and scrapie
Term
Prion Diseases or TSEs
Definition
spread by infectious PrPSC binding to normal PrpPC causing the normal PrP to change shape, which snowball effects by turning more and more normal PrP to abnormal
Term
Variant CJD (vCJD)
Definition
a new form of Creutzfeldt Jakob Disease (CJD) that shows similarities between the animal TSEs
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