Z-Micro Exam 4 Terms

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Capsid

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– protein coat surrounding (protecting) the nucleic acid. Doesn’t resemble a cytoplasmic membrane because it has no permeability. Protein is much tougher than nucleic acid.

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Phage

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– (bacteriophage) a virus that infects bacterial cells. Complex structures.

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Envelope

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– mask some viruses wear to hide even better. Consists of protein, phospholipids, carbs. Resembles the cytoplasmic mem of the host cell. Source of the env is usually the CM of the host. If virus buds out (extrudes), it p;icks up an env (wraps itself in part of cm) which makes it look like a cell to the immune system. Composition is cm of the host when virus exits by budding or extrusion. Fxn= camouflage and protection.

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Host Specificity

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range – virus receptor cite (virus is specific for host). Host cells that a virus can multiply on. Most viruses infect only specific typs of cells in one host species. Host cells a virus can infect.

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lysogenic conversion

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– outcome of lysogeny is that the host bacterial cell and its offspring may exhibit new properties encoded by the phage DNA. Such a change in the characteristics of a microbe due to a prophage is called lysogenic conversion. As a result, the bacterial cell is immune to infection by the same type of phage. DNA is recombined and becomes a part of the host bacterial DNA and is passed on to offspring.

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prion

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– (UDA-1) Proteinaceous infectious particles. All, so far, are neurological. Ex. Spongy brain diseases. Research suggests they are normal proteins that become misfolded.

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filterable

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– Unseen pathogens that passed through the filters causing such diseases as rabies were called filterable viruses. Before electron micrographs, the only evidence of viruses was of filterable quality.
--pass infectious material thru very fine filter. Pores are so small, tiny bacteria can’t pass thru

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capsomere -

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composes most of the mass of a capsid. Protein subunits.

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prophage -

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phage DNA inserted into the host cell’s DNA. In the lysogenic cycle, prophage is replicated each time a cell divides. Pre-cursor to the phage and has the potential to make phage but it is just the DNA. Most prophage genes are turned off (repressed). No transcription. *Intergrated lambda DNA*

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temperate phage

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A phage capable of lysogeny

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viroid -

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(cancer-2, b-394) Short piece of naked RNA about 300-400 nucleotides long with no protein coat. Cause of some plant diseases.

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“naked” virus -

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capsids in viruses that do not have an envelope. Bare capsid. Ebola virus.

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oncogenic -

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(vir&can.-1, b-391) viruses capable of inducing tumors in animals.

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receptor site -

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(b-383) A site on the host cells surface where animal viruses can attach. Are proteins and glycoproteins of the plasma membrane. Virus must chemically interact to infect the host cell. Complementary components are held to/ by weak H bonds.
--some bacteriophages – recptor site is part of the cell wall of the host.
--others it is part of the fimbriae or flagella
--animal viruses – receptor sites are on the plasma membrane of the host cell.

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obligate intracellular -

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(vir-3, b-282) A virus is an obligate intracellular parasite. Requires a living host cell. Only reproduce inside of cells. Can’t isolate in pure colony. Always a parasite.

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lysis –

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destruction of a cell by the rupture of the plasma membrane, resulting in a loss of cytoplasm.. In multiplication, this is caused by lysozyme synthesis in the cell.

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lysogeny –

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bacteriophage incorporates its DNA into host cell DNA. phage remains latent inactive. Phage DNA is incorporated into the host cell without lysis. Don’t go into the cell and make new viruses. Hitchhike. Integrate their genetic material into the host chromosomes. Instead of making new viruses, it parks in the bacterial chromosome. So every time bacterial cell divides, viral DNA is copied. Free ride. Bacterial host cells are lysogenic cells.

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acellular -

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not belonging to any kingdom of life because all viruses are incapable of independent metablolism. No cellular structure.

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complementarity – of fit between phage and host cell.

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Means Ag & Ab fit like a lock and key. (like enzyme and substrate) – broad phenomenon.

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moron gene–

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genes that some bacteriophages carry which are unnecessary for the virus, but helpful for the host bacteria. Genes that some bacteriophages carry which are unnecessary for the virus, but helpful for the host bacteria.

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exogenous retrovirus –

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HIV or free virus. Infectious, animal to animal, person to person. Came from outside not passed down from parent. 1st generation.

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retrovirus –.

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RNA virus that has reverse transcriptase to convert it’s RNA genome into ds DNA and integrates the genome into the host genome

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endogenous retrovirus -

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found inside the hsot, can be dormant for a long time. Integrated its genome into the genome of a germ line (sex) cell. Each time the sex cell divides, the genome of the endogenous retrovirus s also passed along.