Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
77 Cards in this Set
- Front
- Back
|
What is virion?
|
a complete, fully developed viral particle that is INFECTIOUS.
|
|
|
What is a virion composed of?
|
Virion is composed of nucleic acid that is surrounded by a protein coat, called a CAPSID.
|
|
|
What is a capsid?
|
A capsid is a protein coat that surrounds the nucleic acid of a virion.
|
|
|
List the 4 nucleic acid structures for Viruses
|
1. ds DNA viruses (ex. herpes virus)
2. ss DNA viruses (ex. parvo virus) 3. ds RNA viruses (ex. Reovirus) 4. ss RNA viruses (ex. coronavirus) nucleic acid structure of viruses can be LINEAR or CIRCULAR. Some viruses the nucleic acid is in several segments. |
|
|
List the function and structural components of the CAPSID
|
CAPSID is the protein coat that surrounds the nucleic acid core.
Capsid is composed of protein subunits called CAPSOMERES. CAPSOMERES of the capsid are arranged in characteristic of a particular type of virus. |
|
|
What is the structural component of an envelope? It's function? (viruses)
|
A combination of lipids, proteins and carbohydrates that covers the capsid. --a lipid membrane.(some viruses)
Some envelopes have spikes, which are used for attachment to host cell. |
|
|
Where can some animal viruses acquire their envelopes?
|
Some animal viruses can acquire their envelope from the host's cell membrane.
|
|
|
What is significant about viral SURFACE structure?
|
The genes that code for viral surface proteins are susceptible to mutations. Ex. the flu. (when they mutate, they are no longer recognized by antibodies that you made to the previous year's strain of influenza virus.
|
|
|
Name 4 types of Viral Morphology
|
Helical-long rods that may be flexible or rigid, the viral nucleic acid is within the hollow cylindrical capsid. Exanples: Ebola virus and rabies virus
Polyhedral- (many sided) most are icosohedral with 20 triangular faces. Ex. polio virus. Enveloped- when helical or polyhedral viruses are enclosed in an envelope they are called enveloped helical or enveloped polyhedral viruses. Complex- additional structures are attached to capsid. Ex. BACTERIOPHAGE |
|
|
Viral Taxonomy:
Define: Viral species |
Viral species- a group of viruses sharing the same genetic information and ecological niche (host)
|
|
|
What are the categories viruses are based on (TAXONOMY)?
|
1. Type of nucleic acid they have (SS DNA, DS DNA, SS RNA or SD RNA)
2. How they replicate 3. Their morphology |
|
|
What 3 is used to grow viruses?
|
1. Embryonated eggs (This is how flu vaccines are made)
2. Cell cultures (mammalian cells grown in petri dish---add virus to grow) 3. living animals |
|
|
Viruses must be gown on?
|
Living cells or animals only.
|
|
|
What are transformed/continuous cells(growing viruses in cell culture)?
Normal cells/Primary cells grown in cell culture? |
Transformed cells or continuous cell cultures do no grow in monolayer.
Normal cells or primary cells grow in a monolayer across the glass or plastic container. |
|
|
What is a BACTERIOPHAGE?
|
Bacteriophages are viruses that ONLY infect bacteria.
|
|
|
Name and describe the 2 types of VIRAL REPLICATION of bacteriophages or phages
|
1. LYTIC CYCLE- host cell is lysed and killed
2. LYSOGENIC CYCLE-host cell remains alive, does not kill cell, but virus becomes part of bacterial chromosome. |
|
|
List and describe the 5 stages of MULTIPLICATION OF BACTERIOPHAGES in LYTIC CYCLE.
|
1. Attachment- phage attaches by tail fibers to host cell.
2. Penetration- phage lysozyme opens the cell wall, the tail sheath contracts to force the viral DNA into cell. 3. Biosynthesis- Production of phage DNA and proteins 4. Maturation- Assembly of phage particles 5. Release- phage lysozyme break cell wall (kills host cell and ruptures) |
|
|
What part of the virus enters the cell?
|
ONLY DNA. The tail and protein coat stays outside the cell.
|
|
|
Describe maturation stage in lytic cycle of multiplication of bacteriopages
|
Maturation- viral components are assembled into virions
|
|
|
Describe release stage in lytic cycle of multiplication of bacteriopages
|
Release- host cell lyses and new virions are released
|
|
|
Describe biosynthesis stage in lytic cycle of multiplication of bacteriopages
|
Biosynthesis- phage DNA directs synthese of viral components by host cell
|
|
|
Describe penetration stage in lytic cycle of multiplication of bacteriopages
|
Penetration- phage penetrates host cell and injects DNA
|
|
|
Describe the LYSOGENIC CYCLE of the multiplication of bacteriophages
|
1. Viruses attaches and injects its DNA just like lytic cycle.
2. Viral DNA incorporates into the bacterial chromosome and no new virus is made. 3. INTEGRATED viral DNA into host DNA = PROPHAGE 4. Viral DNA can remain dormant for many cell divisions. 5. IMPORTANT- lysogenic cycle can be INDUCED to enter lytic cycle and kill host cell (based on different stimuli). |
|
|
What is a proghage?
|
Integrated viral DNA to host cell DNA (in lysogenic cycle)
|
|
|
What is bacteriophage?
|
Viruses that only infect bacteria.
|
|
|
List and describe MULTIPLICATION OF ANIMAL VIRUSES
|
1. Attachement- viruses attach to cell membrane.
2. Penetration- by 1. endocytosis or 2. fusion 3. Uncoating- by viral or host enzymes 4. Biosynthesis- Production of nucleic acid and proteins. 5. Maturation- Nucleic acid and capsid proteins assemble. 6. Release- by budding (enveloped viruses) or rupture. |
|
|
Describe Endocytosis (Animal viruses multiplication)
|
Endocytosis is when vesicles form around virus particle with host's cell membran. It is pinched off into cytoplasm of host cell, followed by release of virus into host cytoplasm.
|
|
|
Describe Fusion (Animal viruses multiplication)
|
Fusion is when the viral envelope fuses with the host's cell membrane and releases the virus particle into the host's cytoplasm.
|
|
|
MULTIPLICATION of ANIMAL VIRUSES-DNA VIRUSES
|
1. Virion attached to host cell.
2. Virion enters cell and its DNA is uncoated. 3. A portion of viral DNA is transcribed, producing mRNA that encodes "early" viral proteins. 4. Viral DNA is replicated and some viral proteins are made. 5. Late translation; capsid proteins are synthesized. 6. Virions mature 7. Virions are released. |
|
|
FACTS about HERPES VIRUSES
|
1. DNA virus
2. Infects most animals 3. HSV 1-causes cold sores in humans 4. HSV 2- causes genital herpes in humans 5. HHV 3- causes chicken pox in humans 6. All herpes viruses exhibit LATENCY- the viral dna integrates into your DNA and stays with you forever causing periodic outbreak of disease. 8. No cure for latent viruses. 9. about 100 different types |
|
|
What enzyme makes retrovirus to replicate possible?
|
Reverse transcriptase
|
|
|
Stage/Process of Retrovirus Replication
|
1. Retrovirus enters cell by fusion between attachment spikes and the host cell receptors.
2.Uncoating releases the two viral RNA genomes and the viral enzymes reverse transcriptase, integrase and protease. 3. Reverse transcriptase copies viral RNA to produce ds DNA. 4. The new viral DNA is transported into host cell's nucleus, where it is integrated into a host cell chromosome as a provirus by viral integrase. The provirus may be replicated when the host cell replicates. 5. Transcription of the provirus may also occur, producing RNA for new retrovirus genomes and RNA that encodes the retrovirus capsid, enzymes and envelope proteins. 6. Viral proteins are processed by viral prolease; some of the viral proteins are moved to the host plasma membrane. 7. Mature retrovirus leaves host cell, acquiring an envelope and attachment spikes as it buds out. |
|
|
What is the consequence of activated oncogenes?
|
Activated oncogenese ransform normal cells into cancerous cells.
Genetic materials of oncogenic viruses become integrated into host cell's DNA and transforms host cell into cancer cells. |
|
|
What are transformed cells?
|
Cells that have increased or uncontrolled growth--- leading to cancer cells.
|
|
|
What are oncogenes?
|
genetic code in viruses that can transform host cells into cancer cells, when activated.
|
|
|
List 3 types of viral infections
|
1. ACUTE infections- symptoms develop rapidly but last for a short time
2. Latent viral infections- Virus remains in asymptomatic host cell for long periods of time. EX. cold sores, shingles 3. Presistent viral infections- Disease processes ooccurs over a long period of time;fatal. Ex. Subacute sclerosing panencephalitis (measles virus) |
|
|
What are Viriods?
|
Viroids are infectious RNA.
-No protein coat. -Naked pieces of RNA virus that cause diease---only found in plants at this time. |
|
|
What are Prions?
|
-Infectious proteins.
-Naked protein that cause disease and death in humans. -Inherited and transmissible by ingestion, transplant and surgical instruments. -Cause encephalopathies (brain disease); scapie, Creutzfeldt-Jakob disease, kuru (cannobolism), mad cow diease |
|
|
3 things that can happen as a result of Lysogeny
|
1. Lysogenic cells are immune to reinfection by the same phage.
2. Phage conversion- the host cell may exhibit new properties due to genes expressed by prophage. 3. Specialized transduction- upon entering the lytic cycle, some of the host (bacteria) DNA is packaged along the phage DNA inside finished phage particles. |
|
|
What is specialized tranduction (Lysogenic cycle)
|
3. Specialized transduction- upon entering the lytic cycle, some of the host (bacteria) DNA is packaged along the phage DNA inside finished phage particles.
|
|
|
What is Phage conversion (lysogenic cycle)
|
Phage conversion- the host cell may exhibit new properties due to genes expressed by prophage.
|
|
|
What is the function of the interferon? (Therapy for Viral Infections)
|
Interferons (produced by virally infected cells (dsRNA)):
-slows infection of other cells. -it is HOST specific, not virus specific. -can now be genetically enginerred. -activates mRNA-degrading enzyme to stop protein synthesis. Therefore, cell dies and virus can not replicate. |
|
|
Fuction of Amantidine and rimantadine? (influenza A)
|
Viral uncoating (viral therapy)
|
|
|
What is Acyclovir used for(chemical in viral infections therapy)?
|
Acyclovir is useful in treating Herpes infections. Inhibits viral DNA polymerase.
|
|
|
What is Azidothymidine used for(chemical in viral infections therapy)?
|
-competitive inhibitor with thymidine during DNA synthesis from RNA.
-chain termination because next nucleotide can't be inserted. |
|
|
Name the chemical inhibitors involving nucleic acid synthesis
|
1. Nucleoside analogs
-Acyclovir-treating Herpes infections. Inhibits viral DNA polymerase. -Azidothymidine (AZT) used for HIV infections. Thymidine analog is the competitive inhibitor with thymidine during DNA synthese from RNA. There is a chain termination because next nucleotide can't be inserted. 2. Nonnucleoside reverse transcriptase inhibitors (HIV) 3. Nonnucleoside polymerase inhibitors (herpes) |
|
|
What is involved in Assembly and Release (viral therapy-chemical inhibition)
|
Protease inhibitors (HIV)
|
|
|
Define cancer
|
uncontrolled cell growth producing a mass of cells=tumor
|
|
|
Oncogenic viruses causes what % of cancers and provide examples?
|
20% is caused by oncogenic viruses.
Example: -EBV associated with Burkitts Lymphoma -HPV and cervical cancer -Hepatitis viruses and liver cancer. |
|
|
How do oncogenic viruses cause cancer?
|
The genetic material of oncogenic viruses become integrated into host cell's DNA and transforms them into cancer cells=transformed cells. (have uncontrolled or increased growth)
|
|
|
What are oncogenes?
|
Oncogenese are cancer genese in viruses.
|
|
|
What is Proto-oncogene (cellular oncogene)?
|
Proto-oncogenes activate transcription.
|
|
|
What are tumor suppressor genes?
|
Tumor suppressor genes inhibit excessive cell growth; make enzymes for DNA repair.
|
|
|
What is involved of Transformation of cells?
|
Transformation of cells involves integration of viral DNA into host DNA.
-The virus introduces unregulated oncogene -The viral DNA inserts near PROTO-ONCOGENE and affects regulation. |
|
|
Genetic transfer and reconbination provides...
|
...diversity in descendent cells and together with natural selection drive evolution.
Mutation is another source of genertic variation. |
|
|
Describe vertical gene transfer
|
Occurs during reproduction between generations of cells
|
|
|
Describe horizontal gene transfer
|
The transfer of genes between cells in the same generation.
* It is through horizontal gene transfer that rapid spread of antibiotic resistance can occur in bacterial populations. |
|
|
Describe Genetic Recombination
|
Exchange of genes between 2 DNA molecules.
Crossing over occurs when 2 chromosomes break and rejoin. |
|
|
What are plasmids (DNA fragment)?
|
They are small, extrachromosomal circular DNA molecule that replicates INDEPENDENTLY of the chromosome. Often codes for antiobiotic resistance.
|
|
|
How many daughter cells will have a copy of the DNA fragment with no origin of replication?
|
1 daughter cell will have a copy of the DNA fragement (plasmid)
|
|
|
How many daughters cells will have a copy of the DNA fragment that was originally inserted into a bacterial chromosome?
|
all daughter cells will have a copy of the DNA fragment.
|
|
|
Define recombination
|
Recombination is the process of producing a new chromosome.
|
|
|
In the recombination process, which (eukaryotes or prokaryotes) go through the reciprocal process?
|
Eukaryotes go through reciprocal process.
|
|
|
In the recombination process, which (eukaryotes or prokaryotes) go through the nonreciprocal process?
|
Prokaryotes go through nonreciprical process
|
|
|
What is a recombinant?
|
A cell/chromosome that has undergone reconbination.
|
|
|
Describe TRANSFORMATION(Genetic transfer)
|
In TRANSFORMATION:
Dead bacterial cells release DNA into solution and other bacteria take up small pieces of this DNA and incorporate it into their chromosomes. -no cell to cell contact required. No pili needed. -Does not occur naturally among most bacteria. -Streptococcus and Neisseria can go through transformation naturally. Competent bacteria have the ability to take up and integrate donor DNA into their chromosome. Others can be made "competent" int the lab! |
|
|
What is a competent bacteria (transformation)
|
Competent bacteria have the ability to take up and integrate donor DNA into their chromosome.
Others can be made "competent" in the lab. |
|
|
What is Electroporation (transformation)
|
Recipient cells treated with electric current--creates pours in cell membrane that allow fragments of donor DNA to integrate with recipient DNA=transforment cell.
|
|
|
Importance of Transformation
|
1 type of gene transfer and source of genetic diversity used by bacteria in which DNA is transferred to recipient bacteria as "naked" DNA from the environment.
-Converts harmless bacteria to ones that can cause disease or can convert ones that are sensitive to antiobitic to resistant. |
|
|
What is involved in Transduction?
|
In Transduction:
Bacterial DNA is transfered from donor DNA to recipient cell via BACTERIOPHAGE. -During phage assembly, pieces of bacterial DNA are packaged in a phage capsid. -A phage carrying bacterial DNA infects a new host cell, the recipient cell. -Recombination can occur, producing a recombinant cell with a genotype different from the donor and the recipient cell. -Certain bacterial toxins are transferred between bacteria by the bacterial viruses: -diptheria toxin of Corynebacterium diptheriae -erythrogenic toxin of Streptococcus pyogenes -Shiga toxin of E. coli |
|
|
Name 2 forms of Transduction
|
1. Generalized Transduction-prophage integrates anywhere on bacterial genone.
2. Specialized Transduction- prophages integrate into bacterial genone at a SPECIFIC location |
|
|
What is required for conjugation?
|
PLASMIDS
|
|
|
Function of congugative plasmid?
|
Conjugative plasmids carries genes for sex pili and transfer of the plasmid.
|
|
|
Function of dissimilation plasmids?
|
Dissimilation plasmids encode enzymes for catabolism of unusual compounds.
|
|
|
Fuction of R plasmids Resistance factors?
|
FR plasmids Resistance factors encode antibiotic resistance (tend to be broad host range plasmids)
|
|
|
Fuction of Bacteriocins?
|
Bacteriocins encode for virulence factors such as the toxins made by Clostridium tetani, Bacillus anthracis, and Staphylococcus aureus.
|
|
|
What are plasmids?
|
Extra chromosomal circular dsDNA with its own origin of replication-they can replicate independently of the chromosome.
-vary in size (a gew genes to 1000 genes) -Most prokaryotes contain at least 1 plasmid. -low copy # of plasmids per cell or high # copy of plasmids. |
