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-The process by which molicules of a substance, such as a gas or liquid, collect on the surface of another substance, such as a solid. The molecules are attracted to the surface but do not enter the solids minute spaces as in absorption
- Some drinking water filters consist of carbon cartridges that adsorb contaminants
- Thi attachment process of key and lock fitting (attachment factor + receptor = adsorption)
- bacterial virus
- they cause a hole in a layer of bacteria by killing the bacteria
Protein coat that wrapps a nucleic acid genome contained in a virus. (made of capsomeres)
Protein sub-unit of cupsid (forms the coat around the viral nucleic acid)
- Induce or generate cancer
- cells are killed by virus growth and observe a plaque (area w/no living cells), as a hole in the cell layer.
Refers to degenerative changes in cells, especially in tissue culture, and may be associated w/the multiplication of certain viruses.
- The coat that a virus acquires as it exits a cell.
- A protein covalently (share electrons) attached to a carbohydrate
- Surface protein contained in a viron
- Suply the exzymes and building blocks energy necessary to propagate new virons
- Represent sites of viral multiplication in a bacterium or eukaryotic cell
- microscopically observable dark areas of virus particles (accumulations!!)
- Cancers in cells that freely move around normally occur in white blood cells (leuko:white)
- To cause dissolution or destruction of cells
- - An agent capable of lysis
- - A bacterial cell or strain that has been infected w/a temperate virus, one that does not cause cell destruction
- A virus w/an enclosing envelope, consisting only of a nucleocapsid.
- The nucleic acid and surrounding protein coat of a virus
Obligate intracellular parasites:
- Can be maintained only inside living cells
- An area w/no living cells
- Have potential to become lytic
- also called lysogens
- a form of evirus that is integrated into the genetic material of a host cell and by replicating with it can be transmitted from one cell generation to the next without causing lysis.
- Carry out transcription in reverse
- the reading of RNA template to make DNA copy
- Any class of enzyme that catalyze the formation of DNA from RNA template
- When the host cells no longer adhere tightly to the bottom of the cx dish.
- Virus cause cells to fuse together into giant cells
- Normal growth = single layer of cells
- Tumor viruses cause cells to keep growing until piles of cells are visable
- Same mechanism involved when cells of a tumor grow uncontrollably or metastasize.
Solid or tissue cancer
- Virus inducing turors
- Complete virus particles
- Simplest organism on Earth
- completely lack cellular structure and do not have a cytoplasmic membrane to determine inner or outer boundry of a cell.
- Any virus w/its appropriate coating layers
- also called a virion
- Particle and viron are used to refer to the virus' physical structures because viruses are not cells
- 20 identical sides
Because viruses are incapable of replicating outside of a host, they are called:
- Obligate intracellular parasites
What is the size of the largest virus:
- 1/25th the size of the smallest bacterium
What are bacterial viruses called:
- bacteriophages or phages
How does a bacteriophage penetrate the host cell wall:
- They have a needle like tube to propel through the bacterial envelope and inject their nucleic acid inside the host cell
2 main components of nucleocapsids:
- nucliec acid
What are nonenveloped viruses called:
- Naked virus
The placement of viruses into families depends upon which characteristics:
- general size and shape
- naked or enveloped
- is nucleic acid DNA or RNA
What part of the envelope comes from the host cell and virus
- The membrande is from the hose and attachment proteins are from virus
What type of molecule in an enveloped virus is necessary for attachment to the host cell:
- A viral attachment protein that protrudes outside of the viral envelope is necessary for attachment to athe host cell
What are the 7 steps in the lifecycle of a human virus:
- 1. Attachment
- 2. Penetration
- 3. Uncoating
- 4. Nucleic acid replication
- 5. Protein synthesis
- 6. Self-assembly
- 7. Release
- also called adsorption
- host cell receptor and viron attachment components are often related to a lock and key mechanism where the key (attachment factor) can only recognize the cell types that carry the correct lock (receptor).
- Cell penetration by naked virus is mediated by endocytosis (virus tricks cell into taking it inside)
- Membrane fusion; viron envelope fuses w/cell membrane to form a pore through which the nucleocapsid enters.
- Interalized nucleocapsid is uncoated by host enzymes, thus releasing the viral nucleic acid inside the cell.
4. Nucleic Acid Replication:
- DNA viruses replicat in the host nucleus
- RNA viruses replicate in the host cytoplasm
- Tumor viruses turn on cell replication to continue dividing even when the host is trying to stop cell growth
5. Protein Synthesis:
- Viruses use the host cell translational machinery in the host cytoplasm for protein synthesis.
- When proteins bind to other proteins, which results in components of virions pulling together (like a zipper) except no outside energy is required-the binding force provide energy.
- Naked viruses escape by lysing the host cell
- Enveloped viruses bud (push out) through the cell membrane (the membrane coating serves as its envelope)
Adsorption of the virus to the cell depends upon what specific viral and cellualr components:
- Adsorption depends on a viral attachment protein and cell receptor.
What are the 2 types of penetration:
2. Membrane fusion
Where and how does the process of uncoating take place:
- Uncoating is the removal of the viral capsid protein by cellular enzymes in the cell cytoplasm
Where does DNA and RNA replication take place:
- - DNA: cell nucleus
- - RNA: cell cytoplasm
Where does viral translation occur:
- In the host cytoplasm
How does the assembly of intact virions occur:
- Proteins from the coating bind to each other and to the proper nucleic acit, enabling the nucleacapsid to zip together without outside energy
Describe how the release of virons can occur by cell lysis or budding:
- A naked virus simply lyses the cell to release virons
- An enveloped virus acquires a membrane from the host as it passes through the cell membrane
How many phages or virions can be produced in a single growth cycle:
- About 100 phages/bacterium
- About 300,000 animal virons/animal cell in single growth cycle
What are the differences between lytic and lysogenic viruses:
- Lytic viruses always kill the host cell by breaking it open
- Lysogenic viruses enter the cell where DNA integrates into the host cell and become part of it; they then divide w/the cell. If the host cell becomes sick, lysogenic viruses become lytic and escape the dying cell
What are cytopathic effects:
- result when a viral specimen is placed on human tissue in a cx medium
- Cytopathic effect refers to visible changes, microscopic or otherwise, in cells resulting from viral infections
What is plaque:
- Specific type of CPE where cells are killed so that loss of cells gives rise to a hole in the cell layer
How is the inclusion body type of CPE observed:
- Inclusion bodies are normally seen in the microscope as dark areas of viral material
What are the resulting large cells called when many cells fuse together as a result of viral infection:
- Syncytia or giant cells
What changes occur during transformation:
- Viruses cause the cells to keep growing uncontrollably and pile up or form a tumor
What do viruses do to the host DNA - synthesizing machenery:
- Subvert the host cell machinery into making viruses rather than cellular materials
What type of nucleic acid is in a virion:
- RNA or DNA, but not both
Why is tumorigenesis only assiciated with DNA viruses or retroviruses:
- Only occurs when a cell's genes are altered to cause uncontrollable cell division. Only DNA can integrate into the cell's chromosome because the chromosome is DNA
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