ch 17 Flashcards
_____ are infectious agents that are must have a host.
They lack machinery to make proteins, but they hijack the machinery of their host.
All of these agents contain a nucleocapsid, a nucleic acid, and a capsid. They are incapable of metabolism, replication or motility.
Virus
_____ viruses contain a ssDNA or dsDNA in nucleocapsid.
- dsDNA may directly be used for transcription and replication.
- ssDNA must form a dsDNA intermediate before it is used.
DNA viruses
_____ viruses contain either ssRNA or dsRNA in nucleocapsid.
- RNA polymerase must be encoded before replication because cell hosts do not contain an enzyme that can make RNA from an RNA template.
RNA viruses
Twort and d’Herelle discovered agents too small to be seen with a light microscope, passed through filters and only grew in cell-containing media.
This agent was first called the “_____ virus”, the term was later dropped.
Filterable
Virus means “_____,” a term once applied to all infectious agents.
poison
If a virus is found outside a cell host, its called a _____. This also applies when describing physical attributes of a virus particle.
virion
In a virion, the _____ is a protein coat, with capsomeres. They all protect the nucleic acid from enzymes, toxic chemicals and may carry enzymes required for infection of host cells.
Capsid
At a minimum, the _____ is a particle that consists of a nucleic acid surrounded by a protein coat. Found outside the host cell.
Virion
(viral particle)
The _____ is the combination of a viral genome and viral capsid.
nucleocapsid
A type of phage called the _____ infects bacteria.
Most are non-enveloped, a large variety of shapes, genomes, and replication strategy.
Bacteriophages
(phages, [phages, eat])
Bacteriophages are used as a _____ organism since they’re;
- easy to cultivate
- helps understand molecular biology
- ecosystems
- horizontal gene transfer
- limit bacteria growth
- medical applications
- food production
- storage applications
Model
_____-proteins are structural protein created by phages, that are synthesized by the end of the cycle of infection. Examples (a capsid, tail, etc).
Late-Proteins
_____ - _____ is the number of phage particles released.
Burst-Size
______ phage have the option of either directing a lytic infection or incorporating DNA into host cell genome.
Temperate Phages
In a virion, the capsid contains _____, the identical protein subunits arranged in a precise manner.
Capsomeres
_____ virus have a lipid-bilayer outside the capsid, obtained from the host cell.
Enveloped viruses
In viruses, the _____ protein layer that is fond between the nucleocapsid
(nucleic acid + capsid) and the envelope.
Matrix Protein
_____ - _____ virus that does not have an envelope, a lipid-bilayer outside the capsid.
Non-Enveloped Viruses
(Naked Viruses)
_____ are types of proteins that allow virions to attach (absorb) to specific receptor sites on a host. They stick out from either the lipid bilayer or capsids.
Attachment Protein
_____ _____ is a type of binding between host cell and virion proteins. Binding allows entry of viral genome into a host cell, allowing signaling pathways or infection.
Viral attachment
_____ are protein structures in Phages.
Fibers
_____ are structures in Animal viruses.
Spikes
Viruses have one of these three shapes,
the _____ shape appears symmetrical, polyhedral, spherical, but the surface is actually 20 flat triangles like a soccer-ball.
Icosahedral
Viruses have one of these three shapes,
the _____ shape appears cylindrical but their capsomers are arranged in a helix, like a spiral staircase.
Helical
Viruses have one of these three shapes;
the _____ shape(s) are more complicated, like phages.
Complex
Viruses are inert particles, incapable of ______, replication, or motility. Unless in the active state, where they manipulate the cellular function of the host.
Metabolism
Virons do not generate or store _____, but viruses derive this type of energy from the host cell.
ATP
A _____ infection is likely to occur if host cell slows growth. Temperate phage incorporates DNA within the host, without causing damage. The prophage is replicated along with host cell chromosome.
Lysogenic Infection
A _____ bacteria cause lysogenic infections. If another lambda phage injects DNA into a lambada lysogen, the DNA will not be expressed, this is known as immunity to superinfection.
Lysogen
Lysogenic _____, the change in the phenotype of host cell genome by lysogens, which bacteriophages may encode toxins.
Lysogenic Conversion
The _____ is the genetic material of a bacteriophage, incorporated into the genome of a bacterium and able to produce phages if specifically activated.
Prophage
A _____ protein, which phages carry prevent expression of the genes required for excision and essential for the lysogenic state.
Repressor
The _____cycle from the entry of phage nucleic acid to exit takes 30 minutes.
Phage Cycle
The (1) step in the phage cycle, ______, is where the Phage particles attach with host cells at random; the protein on phages tail attaches to a receptor of host cell surface or appendage, exploiting entrance;
Attachment
The (2) step in the phage cycle, ______ ______ includes a feature all viruses have, where the nucleic acid is separated from the virus’s protein coat before replication.
Genome Entry
The (3) in the phage cycle, ______ the Phage takes over control of host metabolism within minutes of Phage DNA entrance. Early viral proteins are synthesized and transcribed, such as Nuclease and Phage Proteins. Host gene expression is stoped, reaming host proteins continue to function. At the end cycle, late proteins are synthesized.
Synthesis
The (4) step in the phage cycle, ______ is where the synthesized late proteins begin are assemble new phage particles. DNA is packed into the phage head after they self-assemble or assemble with scaffolding proteins that are not part of the Phage Structure.
Assembly (maturation)
The (5) step in the phage cycle, ______ is a late infection, lysozyme is produced in Phages, the enzyme digests host cell wall within, causing the cell to lyse and ultimately releasing Phages. Lastly infecting susceptible cells and replication is repeated.
Release
Non-enveloped virions enter by receptor-mediated ______. Uncoating releases the nucleic acid from the protein coat.
endocytosis
In animal viral replication, this step is #______, the synthesis of viral proteins and replication, of the Genome.
- DNA viruses generally replicate in the nucleus and use the host cell machinery for DNA synthesis as well as gene expression, although they often encode their own DNA polymerase.
- Replication of ssDNA viruses is similar to that of double-stranded DNA viruses, but the complementary strand must be synthesized first. RNA viruses usually replicate in the cytoplasm.
- Replication requires a virally encoded replicase to synthesize the complementary RNA strand. This enzyme lacks proofreading ability and makes more mistakes in replication than DNA polymerase. Reverse-transcribing viruses encode reverse transcriptase, which synthesizes DNA from an RNA template.
- As with replicas, these enzymes are error-prone.
3
In animal viral replication, this step is #______, are assembly and maturation, Capsids are formed, and then the genome and any necessary proteins are packaged within it. The process may take place in the cytoplasm, nucleus, or in a variety of organelles.
4
In animal viral replication, this step is #______, is Release.
Enveloped virions most often exit by budding. Non-enveloped virions are released when the host cell dies.
5
In animal viral replication, this step is #______, attachment.
Attachment proteins or spikes on the viral particle attach to specific receptors on the cell surface.
1
In animal viral replication, this step is #______, are Penetration and Uncoating. In the case of animal viruses, the entire virion enters the cell. Enveloped viruses either fuse with the host membrane or are taken in by receptor-mediated endocytosis.
2
Synthesis is the #______ step in the viral replication of bacteriophages.
3
Genome Entry is the #______ step;
in the viral replication of bacteriophages.
2
Release is the #______ step;
in the viral replication of bacteriophages.
5
Attachment is the #______ step;
in the viral replication of bacteriophages.
1
Assembly (maturation) is the #______ step;
in the viral replication of bacteriophages.
4
This type of _____ host lacks the receptor used by a given phage are resistant to infection by the specific phage.
Cells
In the first step of generalized infections of Animal Virus Replication is Attachment, where animal viruses enter the cell, go through uncoating process, but Bacteriophage receptors are ______. This process is not needed for bacteriophage since only the nucleic acid enters the bacterial cell and not the entire vision.
Unrelated
_____ is the process where nucleic acid separates from capsid.
Uncoating
_____ is the release mechanism out of the cell depends whether virion is enveloped, most enveloped viruses are released by a process where virus acquires its envelope.
Budding
In one of the three types of RNA genomes, _____ genome is the positive single-stranded RNA.
(+) ssRNA
In one of the three types of RNA genomes, the _____ genome is the negative single-stranded RNA.
(-) ssRNA
In one of the three types of RNA genomes, the _____ is double-stranded RNA.
dsRNA
(+) ssRNA can act like _____, so the viral genome can be directly translated by a host ribosome as soon as it enters the cell.
mRNA
(-) ssRNA (like influenza and rabies) must first make a complimentary (+) ssRNA strand from the _____ ssRNA strand template.
negative
(-) ssRNA (like influenza and rabies) must first make a complimentary (+) ssRNA strand from the (-) ssRNA strand template. That means (-) ssRNA virus must bring their RNA directed RNA polymerase enzyme in their ______ so they can use it once they enter the cytoplasm.
Capsid
_____essay routinely used to quantitate phage particle in samples in sewage, seawater and soil. The essay consists of a double layer agar, the soft agar is inoculated with both host and phage specimens, then poured over surface.
Plaque assay
_____ are the circular zones of clearing, form in the lawn due to cell lysis caused by the phage. Each represents a PFU.
Plaque
Viral _____ infections in animals characterized by sudden onset of symptoms of relatively short duration.
Acute Infections
Viral _____ infections in animals that can continue with or without symptoms for years or even the life of the host.
Persistent Infections
_____ infections in animals
that is characterized by the continued production of low levels of viral particles. If infected cell survives, it releases viral particles slowly. If infected cell lysis, and if a small proportion of cells infected at any given time results in a low number of viral particles continuously released.
Chronic Infections
Viral _____ infection, where the viral genome remains silent with a host cell, yet it can reactivate to cause productive infection. If viruses do not integrate into a host cell, chromosome, then they replicate independently of the host genome.
Latent Infections
Hepatitis B Virus
is a ______ infection. The cells involved include hepatocytes (liver cells). Disease symptoms are hepatitis, cirrhosis, hepatocellular carcinoma.
chronic
HCV (Hepatitis C Virus)
is a ______ infection. The cells involved include hepatocytes (liver cells). Disease symptoms are Hepatitis, cirrhosis, hepatocellular carcinoma.
Chronic
HSV-1 is a _____ infection.
(Herpes Simples Virus Type 1)
Latent
HSV-2
is a _____ infection.
The cells involved include neurons of sensory ganglia. Disease symptoms are genital herpes and recurrent genital herpes.
(Herpes Simples Virus Type 2)
Latent
VZV
is a ______ infection. The cells involved include satellite cells of sensory ganglia. Disease symptoms are chicken box and shingles.
(Varicella Zoster, Herpesviridae family)
latent
CMV
is a _____ infection. The cells involved include salivary glands, kidney epithelium, leukocytes. Disease symptoms are pneumonia, eye infections, mononucleosis, congenital infections.
(Cytomegalovirus, Herpesviridae family)
latent
EBV
is a ______ infection. The cells involved include B-cells which are involved in antibody production. Disease symptoms are Burkitt’s lymphoma.
(Epstein-Bar Virus)
latent
HIV
is a _____ infection. The cells involved include activated helper T cells, macrophages. Disease symptoms are AIDS.
(Human immunodeficiency virus)
chronic
HIV
is a _____ infection. The difference here is that the memory helper T-cells are affected.
(Human immunodeficiency virus)
Latent
The _____ is the silent viral genome cannot be eliminated from the body.
Provirus
_____ Viruses,
carry specific genes, which are similar to DNA sequence to proto-oncogenes.
They lead to tumor formation. Mast majority of viruses that cause cancer is due to mutations in host genes. 15 HPV’s are associated with cancers.
Oncogenes
The suffix of animal viruses families
that come from a variety of sources. Italicized, follows no consistent pattern. Prefixes in some cases are descriptions or locations.
-viridae
The suffix of animal viruses families that contains numerous genera. Often prefix is the name of the disease.
-virus
The _____ virus group mechanism of transmission is the fecal-oral route. Common viruses include enterovirus (polio, coxsackie B); noroviruses; rotaviruses (diarrhea).
Enteric
The _____ virus group mechanism of transmission is the respiratory or salivary route. Common viruses include influenza; measles; rhinoviruses (colds).
Respiratory
The _____ virus group mechanism of transmission is via to animal to human directly. Common viruses include rabies; cowpox.
Zoonotic
The _____ virus group mechanism of transmission is via Vectors (arthropods), not to be confused with zoonotic groups. Common viruses include sandfly fever, dengue fever; West Nile encephalitis; La Crosse encephalitis, yellow fever.
Arboviruses
The _____ transmitted virus group mechanism of transmission is via sexual contact.
Common viruses transmitted are Herpes simplex virus type 2 (genital herpes); HIV
Sexual Transmitted
The _____ phage(s) lyses host cell to exist at end of the infection cycle. Infections result in the formation of new viral particles, productive infections.
Lytic Phages (or, Virulent Phages)
The _____ infections result in the formation of new particles.
Productive Infections
The _____ phage that is most extensively studied. Receptors are located on the cell wall. Burst-Size is about 200.
T4 phages
The T4 _____ enzyme is located on the T4 Phages tip of the tail. It is used to degrade a small portion of peptidoglycan of host cell wall.
T4 Lysozyme
Plant viruses can be transmitted through _____ contaminated by the prior growth of infected plants, and by growers themselves.
soil
A _____ percentage of the known plant viruses are transmitted through contaminated seeds, tubers, or pollen.
small
Viruses can also spread through ______ of healthy plant tissue onto diseased plants. Tobacco mosaic virus is transmitted- ted to healthy seedlings on the hands of workers who have been in contact with the virus from infected plants.
grafting
The most important transmitters of plant viruses are probably ______; thus, insect control is a critical tool for preventing the spread of plant viruses.
insects
Viruses are considered as _____ _____, they do not fit the definition of life and thus are not organisms. In essence, viruses straddle the definition of life.
Infectious Agents
A virus contains only _____ single types of nucleic acids, the genome may be linear or circular, either double-stranded or single-stranded. Often termed as DNA viruses or RNA viruses.
One
The _____ microscope is used to see most viruses, minus the Mimivirus or Pandoraviruses as examples, which can be seen using a light microscope.
Electron Microscope
_______ are ssRNA molecules that forms a closed ring, one-tenth the size of the smallest infectious viral RNA genome known.
Viroids
_____ are Infectious agents composed solely of protein. They are linked to a number of slow, always fetal, human diseases. These proteins accumulate in neural tissue for unknown reasons, neurons die and brain function deteriorates as the tissue develops characteristics of holes, sponge-like appearance.
Prions
All _____ diseases cause transmissible spongiform encephalopathies.
All prion diseases.
The _____ is the normal cellular prion protein. Easily destroyed by host cell proteases.
PrPc
(prion protein cellular)
The _____ is the infectious form of the prion, the shape influences stability. It is less susceptible to degradation by proteases and becomes insoluble, leading to aggregation. Not resistant to heat and chemical treatments for inactivating infectious agents.
PrPsc
(prion protein, scrapie)
The _____ is a prion disease with the host of sheep and goats. No human deaths associated.
Scrapie
The _____ is the prion diseases with the host of cattle.
BSE (Bovine Spongiform Encephalopathy, mad cow disease)
Prion diseases with the host of deer and elk. No human deaths associated. This diseases spread from Colorado to wild deer populations, captive farmed animals located in states and Canada. Spread through direct animal to animal (nose to nose) contact.
CWD (Chronic Wasting Disease)
The _____ is the prion diseases with the host of ranched mink.
TME (Transmissible Mink Encephalopathy)
The _____ is the prion diseases with the host of Antelope in South Africa.
EUE (Exotic Ungulate Encephalopathy)
The _____ is the prion diseases with the host of Cats
FSE (Feline Spongiform Encephalopathy)
The _____ is the prion diseases with the host of humans, caused by cannibalism.
Kuru
The _____ is the prion disease with the host of humans (caused by consumption of prion-contaminated beef). Similar to mad cow disease. People ate infected tissue.
VCJD
(Variant Creutzfeldt-Jacob Disease)
Prion _____ inherited diseases such as Creutzfeldt-Jakb Disease, Gerstmann-straussler-scheinker syndrome and fatal familial insomnia.
Humans (inherited)
All known viroids infect only plants, where they cause serious diseases, including potato spindle tuber, chrysanthemum stunt, citrus oxcarts, cucumber pale fruit, hopstunt, and cadang-cadang. Like plant viruses, they enter plants through _____ sites rather than binding to specific receptors.
wound
The _____ is a disease caused by a lethal viroid. Killed all but 100/250M palms in the Philippines by 1962. Today this affects the production of copra, the raw material for coconut oil and animal feed. It affects the;
- coconut,
- Anahow,
- Buri
- African Palm Oil.
CCCVd (Cadang-cadang)
A type of antigenic variation called Antigenic _____ occurs as a mutation accumulates in genes encoding key viral surface proteins that are recognized by the immune system. The immune response may work one year but not for the variant that circulates the next year.
Antigenic Drift
Antigenic _____ is where virus with a segmented genome that undergoes reassortment, when a new subtype of the virus is formed by reassortment between different strains of a virus, or even between different viruses, this is what the phenomena is called.
Antigenic Shift
_____ is where viruses trigger a normal cellular process, also referred to as programmed cell death prior to the release of the viral particles.
Apoptosis
(or programmed cell death)
Influenza viruses, for example, exhibit a type of antigenic variation called _____ _____. Because of this, a person immune response from one year may not protect against the influenza virus the next year.
antigenic drift
