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59 Cards in this Set

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