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Exam III
SCC Bio 229
76
Microbiology
Undergraduate 1
04/18/2014

Additional Microbiology Flashcards

 


 

Cards

Term
electrophoresis
Definition
a technique that involves separating molecules based on their electrical charge, size, and shape
Term
gel electrophoresis
Definition
DNA molecules have an overall negative charge are drawn through a semisolid gel (agarose) by an electrical current toward the positive electrode in an electrophoresis chamber. smaller fragments travel faster and further.
Term
DNA microarray
Definition
consists of ssDNA, either genetic DNA or cDNA, immobilized on glass slides, silicon chips, or nylon membranes.
purpose: monitoring gene expression, diagnosing infection, identifying organisms in an environmental sample
Term
electroporation
Definition
involves using an electral current to puncture microscopic holes through a cell's membrane so that DNA can enter from the environment. can be used on all types of cells.
Term
protoplast
Definition
cells that have had their cell walls enzymatically removed
Term
protoplast fusion
Definition
when protoplasts encounter one another, their cytoplasmic membrane's may fuse to form a single cell that contains the genomes of both "parent" cells. exposure to polyethylene glycol increases the rate of fusion. the DNA from the two fused cells recombines to form a recombinant molecule. often used for genetic modification of plants.
Term
injection (inserting DNA)
Definition
two types of injection: gene gun & microinjection. injection can be used on intact tissues such as in plant seeds.
Term
gene gun
Definition
0.22-caliber cartridge or compressed gas powers the firing of tiny tungsten or gold beads covered with DNA into a target cell. the cell eventually eliminates the inert metal beads.
Term
microinjection
Definition
DNA is inserted into a target cell with a glass micropipette having a tip diameter smaller than that of the cell or nucleus.
Term
DNA fingerprinting
Definition
identifying individuals or organisms by their unique DNA sequences. any given sequence is a unique pattern and must be compared to patterns produced from other DNA molecules. genetic fingerprinting can be used to determine paternity, for forensics, and also for identifying pathogens.
Term
virus
Definition
acellular, miniscule, infectious agent usually having one or more pieces of nucleic acid- either RNA or DNA. they lack cytoplasmic membranes, cytosol, functional organelles. not cappable of metabolic activity on their own; must invade cells and take over the host cell's metabolic machinery
Term
virion
Definition
a virus outside of the cell, in the extracellular state. consists of a capsid surrounding the nucleic acid, together called the nucleocapsid. some virions have an envelope surrounding the nucleocapsid.
Term
capsid
Definition
protein coat surrounding nucleic acid core
Term
nucleocapsid
Definition
the nucleic acid and its capsid, together
Term
envelope
Definition
phospholipid membrane surrounding a viral nucleocapsid. consists of phospholipid bilayer and proteins. some have glycoproteins appearing as spikes. proteins and glycoproteins play a role in host recognition.
Term
generalists
Definition
viruses that are capable of infecting may kinds of cells in many types of hosts
Term
bacteriophage
Definition
virus that infects bacteria. aka phage.
Term
capsomeres
Definition
proteinaceous subunits of a capsid
Term
helical virus
Definition
virus composed of capsomeres that bond together in a spiral fashion to form a tube around the nucleic acid
Term
polyhedral virus
Definition
viral capsid is roughly spherical, with a similar shape to a geodesic dome. most common type is an icosahedron, which has 20 sides.
Term
complex virus
Definition
capsids of many different shapes that do not fit into either of the other viral shape categories.
Term
matrix proteins
Definition
viral proteins that fill the region between the envelope and the capsid
Term
ICTV
Definition
International Committee on Taxonomy of Viruses, established in 1966 to provide a single taxonomic scheme for viral classification and identification
Term
lytic replication cycle
Definition
process of viral replication consisting of five stages ending with lysis of and release of new virions from the host cell. includes 5 stages: attachment, entry, synthesis, assembly, and release.
Term
attachment (viral replication)
Definition
1st stage of viral replication. dependent upon the chemical attraction and precise fit between attachment proteins and complimentary receptor proteins on the surface of the host's cell wall
Term
entry (viral replication)
Definition
2nd stage of viral replication. phage releases lysozyme, a protein enzyme carried within the capsid that weakens the peptidoglycan of the cell wall. the phage injects its genome into the bacterium.
Term
synthesis (viral replication)
Definition
3rd stage of lytic replication and 5th stage of lysogenic replication: after entry, viral enzymes degrade the bacterial DNA into consituent nucleotides. the bacterium stops making its own molecules and begins synthesizing new viruses.
Term
assembly (viral replication)
Definition
4th stage of lytic replication and 6th stage of lysogenic replication: as capsomeres accumulate within the cell, they spontaneously attach to one another to form new capsid heads. then tails assemble and attach to heads, forming mature virions. requires little to no enzymatic activity.
Term
release (viral replication)
Definition
newly assembled virions are released from the cell as lysozyme completes its work on the cell wall and the bacterium disintegrates.
Term
burst time
Definition
the period of time required to complete the entire process of lytic viral replication, from attachment to release.
Term
burst size
Definition
the number of new virions released from each lysed bacterial cell
Term
lysogenic replication cycle
Definition
modified viral replication cycle in which the bacteriophage enters a bacterial cell, inserts itself into the host DNA, and remains inactive. the phage is then replicated every time the host cell replicates its chromosome. later, the phage may lyse.
Term
temperate phage
Definition
aka lysogenic phage. bacteriophage that does not immediately kill its host but replicates through lysogeny
Term
prophage
Definition
an inactive bacteriophage, which is inserted into a host's chromosome
Term
latency (viral replication)
Definition
3rd stage of lysogenic replication. once phage enter's the bacterium and inserts itself into the host DNA, the prophage remains inactive.
Term
lysogenic conversion
Definition
lysogenic phages can change the phenotype of a bacterium, for example from a harmless form to a pathogen.
bacteriophage genes are responsible for toxins and other disease-evoking proteins found in cholera, diptheria and rhuematic fever.
Term
induction
Definition
4th stage of lysogenic replication. process whereby the prophage is esxcised from the host chromosome. inductive agents are typically the same chemical and physical agents that damage DNA molecules such as UV light, x-rays, and carcinogenic chemicals
Term
attachment of animal viruses
Definition
animal viruses lack both heads and tail fibers. instead, they typically have glycoprotein spikes or other attachment molecules on their capsids or envelopes.
Term
entry of animal viruses
Definition
3 different mechanisms: direct penetration, membrane fusion, and endocytosis.
Term
direct penetration
Definition
method of entry for animal viruses. process in which the viral capsid attaches and sinks into the cytoplasmic membrane, creating a pore trhough which the genome alone enters the cell. ie, poliovirus
Term
membrane fusion
Definition
method of entry for animal viruses. the viral envelope and the host cell membrane fuse together, releasing the capsid into the cell chromosome. ie, measles and AIDs virus.
Term
endocytosis
Definition
most enveloped animal viruses and some naked animal viruses enter host cells by triggering endocytosis. attachment of the animal virus to receptor molecule's on the cell's surface stimulates the cell to endocytize the entire virus. ie, adenovirus and herpes virus.
Term
uncoating
Definition
the removal of a viral capsid within the host cell (for animal viruses that enter the host cell with their capsid intact)
Term
synthesis of animal viruses
Definition
each type of animal virus requires a different strategy for synthesis depending upon the kind of nucleic acid involved
Term
dsDNA: animal virus synthesis
Definition
cellular enzymes replicate the viral genome in the same manner as they replicate host dsDNA, using each strand of the viral DNA as a template for its complement
Term
ssDNA: animal virus synthesis
Definition
when a parovirus enters the nucleus of a cell, host enzymes produce a new strand of DNA complementary to the viral genome which then binds to form dsDNA. transcription of mRNA, replication of new ssDNA, and viral assembly then follow the DNA virus pattern.
Term
parvovirus
Definition
a human virus composed of ssDNA
Term
+ssRNA: animal virus synthesis
Definition
single stranded viral RNA that can act directly as mRNA; ribosomoes translate polypeptides using the codons of the viral genome. a complimentary -ssRNA strand is transcribed by viral RNA transcriptase in order to be used as the template for more +ssRNA
Term
retroviruses: animal virus synthesis
Definition
ssRNA viruses that do not use their genomes as mRNA but instead use reverse transcriptase to transcribe the viral genome into intermediary DNA. the DNA then acts as the template for +RNA molecules, which act as both mRNA and also as genomes for new virions
Term
-ssRNA: animal virus synthesis
Definition
-RNA is not recognized by ribosomes. virus must carry "RNA-dependent RNA transcriptase" within its capsid and release into the host cytoplasm during uncoating. RNA-dependent RNA transcriptase transcribes +RNA from the virus' -RNA genome. the +RNA will act as the mRNA as well as the template for transcription of more -RNA viral copies.
Term
dsRNA: animal virus synthesis
Definition
the positive strand of genome serves as mRNA for the translation of proteins, one of which is RNA polymerase that transcribes dsRNA. each strand acts as a template for transcription of its opposite.
Term
assembly of animal viruses
Definition
most DNA viruses assemble in and are released from the nucleus into the cytosol. most RNA viruses develop solely in the cytoplasm.
Term
release of animal viruses
Definition
enveloped viruses are released via a process called budding- assembled virions are extruded through cell membranes acquiring a portion of the membrane which becomes the viral envelope. naked animal viruses may be released via exocytosis or they may cause lysis and death of the host cell.
Term
persistent infections
Definition
infections with enveloped viruses in which host cells shed viruses slowly and relatively steadily
Term
latency
Definition
some animal viruses can remain dormant in cells. some viruses do incorporate their genome into the host chromosome while others do not.
Term
proviruses
Definition
aka latent viruses.. viruses involved in latency
Term
neoplasia
Definition
phenomenon of uncontrolled cell division in a multicellular animal
Term
tumor
Definition
mass of neoplastic cells
Term
beign
Definition
tumors which remain in one place and are not generally harmful
Term
malignant
Definition
tumors that invade neighboring tissues and even travel throughout the body to invade other organs and tissues to produce new tumors
Term
metastasis
Definition
spreading of malignant cancer cells to nonadjacent organs and tissues, where they produce new tumors
Term
cancer
Definition
disease characterized by the presence of one or more malignant tumors
Term
protooncogenes
Definition
genes that play a role in cell division. normally repressed.
Term
oncogenes
Definition
active protooncogenes. activity of oncogenes or inactivation of oncogene repressors can cause cancer to develop.
Term
viral cancers
Definition
20-25% of human cnacers are caused by viruses. examples include- Burkitt's lymphoma, Hodgkin's disease, Karposi's sarcoma, and cervical cancer
Term
plaques
Definition
in phage typing, the clear regions within the bacterial lawn where growth is inhibited by bacteriophages
Term
plaque assay
Definition
technique for estimating phage numbers in which each plaque corresponds to a single phage in the original bacterium/virus mixture
Term
cell culture
Definition
cells isolated from an organism and grown on the surface of a medium or in broth. viruses can be grown in a cell culture.
Term
diploid cell culture
Definition
type of cell culture created from embryonic animal, plant, or human cells that have been isolated and provided appropriate growth conditions
Term
continuous cell cultures
Definition
type of cell culture created from tumor cells; longer lasting
Term
viroids
Definition
extremely small, circular piece of RNA that is infectious and pathogenic in plants
Term
prions
Definition
proteinaceous infectious particle that lacks nucleic acids and replicates by converting similar normal proteins into new prions.
Term
chemotherapeutic agents
Definition
drugs that act against diseases
Term
antibiotics
Definition
anitmicrobial agents that are produced naturally by an organism
Term
semisynthetics
Definition
chemically altered antibiotics
Term
selective toxicity
Definition
prniciple by which an effective antimicrobial agent must be more toxic to a pathogen than to the pathogen's host
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