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59 Cards in this Set
- Front
- Back
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viral genomes
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single strand DNA or double stranded RNA
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capsid
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protein shell that protects the DNA of a virus
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Viral envelopes
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glycoproteins that cloak the viruses found in animals
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bacteriophages
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virus that infect bacteria
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T2, T4, and T6
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bacteriophages that infect the bacterium E. coli
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host range
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limted due to proteins on the outside of the virus that recognize only specific receptor molecules on the host cell surface.
-means each virus type has a limited range of hosts it can infect. |
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what happens after viral DNA is injected into host?
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the cell's enzymes,nucelotides, amino acids, and other machinery make copies of the host DNA polymerases to copy their genome
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how do RNA viruses replicate?
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they use virus-encoded polymerases for replicating their RNA genome
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after viral DNA replication in host ?
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capside proteins, and viral DNA assemble to form new virus particles within the host cell
- hundreds of thousands of viruses produced. |
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lytic cycle
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replication cycle of a virus that culminates lysis of the host cell and releases produced phages
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virulent viruses
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viruses reproduced only by a lytic cycle
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lysis
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cell bursts
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how do bacteria defend against viral infection?
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-mutattion change receptor sites
-produece restriction nucleases that chop up viral DNA once it enters the cell |
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lysogenic cycle
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virus reproduces without killing its host
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temperate viruses
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reproduce by te lytic and lysogenic cycles
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lambda phage λ
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phage that injects its DNA into E. coli
- enters lytic cycle or ebegins lysogenic cycle as a phrophage |
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prophage
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a phage genome inserted as part of the structure of the DNA chromosome of a bacterium.
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provirus
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a virus that has integrated itself into the DNA of a host cell.
ex. herpes - retrovirus can become a provirus. |
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retroviruses
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viral RNA genome is transcribed into double-stranded DNA by reverse transcriptase
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reverse transcirptase
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viral enzyme that transcribes RNA into DNA
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HIV
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human immunodeficiency virus
- retrovirus that caused AIDs |
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AIDS
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acquired immunodefiency syndrome
-cause by retrovirus |
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vaccines
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variants or derivaties of pathogens that induce the immune system to react against the components of the viruses themselves
ex. smallpox |
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how do new viruses emege?
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through mutation of an existing virus
ie: influenza |
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tumor viruses
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viruses that can cause cancer in animals
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oncogenes
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genes responsible for triggering cancerous transformations
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proto-oncogenes
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oncogenes found within the genomes of normal cells
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plant viruses
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most plant viruses are RNA viruses
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viroids
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very small molecules of naked circular RNA
- disrupt growth in plants |
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prions
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protein infectious agents that cause degenerative brain disease.
ie, mad cow disease |
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nucleoid
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tightly packed region of bacteria cells
- contains DNA |
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transformation
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-bacteria process
-foreign DNA is integrated into the bacterial chromosome via crossing over |
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trandsduction
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-random piece of host DNA is accidently packaged within a phage capside and introduced in new bacterium
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specialized trandsduction
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bacterial genes adjacent to a prophage insertion site are excised with the prophage from the bacterial chromosome
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conjugation
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when two cells temporarily join by sex pilli
-transfer DNA |
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F factor
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the ability to form sex pili
-piece of DNA that is located on either the chromosome or plasmid |
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plasmid
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small circular DNA
- in bacteria |
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episomes
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plasmids that can reversibly incorporate in the cell's chromosome
ie: temperate viruses |
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F+
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bacterial cells containing the F factor on the F plasmid
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R plasmids
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carry genes that code for antibiotic destroying enzymes
( destroy things that kill bacteria) - can be transferred during conjugation |
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F proccess
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F plasmid replicates and is transferred to the recipient cell from an F- to and F+ cell
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F-
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-recipient of F plasmid
-female -doesn't have F plasmid |
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F +
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- donar of the F plasmid
- male -has F factor on the F plasmid |
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transposon
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transposable genetic elements
-mobile segments of DNA that may move within a chromosome to and from plasmids |
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cut and paste transposition
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transposon changes location
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replicative transposon
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transposon first replicates then moves clone into new location
( in two places at once) |
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insertion sequences
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enzymes cuts DNA required for transposation
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operator
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- a segment of DNA which regulates the activity of the the genes of an operon
- regulatory sequence for shutting a gene down or turning it "on". |
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operon
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DNA segment that includes the promoter and the operator
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promoter
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-a DNA sequence that enables a gene to be transcribed.
- recognized by RNA polymerase, which then initiates transcription |
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repressor
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protein that binds to a specific operator, blocking attachment of RNA polymerase
-turns operon off stops transcription |
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corepressor
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its presence dtermins the activity of the repressor
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trp operon
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tryptophan binds the the repressor protein, thus activating it
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repressible operon
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inhibited when a ligand binds to a regulatory protein
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inducible operon
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transcribed when a ligand enteracts witha regulatory protein
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lac operon
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-controlls lactose metabolism
-is inducible operon |
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inducer
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small molecule that binds to and inactivates the repressor proteibn sot the operon can be transcribed
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cAMP receptor protein
(CRP) |
CRP
regulatory protein |
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Cyclic AMP
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accumulates in the cell when glucose is abssent and binds with CRP chaings it to its active shpae
-active CRP attaches near the promoter region and stimulates trasncriptions via the binding of RNA polymerase |
