viral genetics Flashcards
viral genome
may consist of double or single stranded DNA, double or single stranded RNA
capsid
protein shell enclosing the viral genome built from capsomeres
viral envelope
surrounds the capsids and is derived from the membrane of the host cell; contains host cell membrane proteins and phospholipids
bacteriophage
viruses that infect bacteria and have the most complex capsids
RNA viral genes
include specialized virus encoded polymerase that use RNA as a template
lytic cycle
last stage of infection, where bacterium lyses open and releases phages produced within cell
virulent phage
bacteriophage that reproduces only by a lytic cycle
lysogenic cycle
replicates the phage genome after the viral genome enters by genetic recombination
temperate phage
phage capable of using both lysogenic and lytic cycle for replication
prophage
after being integrated into the bacterial chromosome the viral DNA is a prophage that blocks transcription of viral genes
enveloped viruses
not all viruses have envelopes; reproductive cycle that allows virus to export and infect other cells without lysing cell
retrovirus
RNA animal virus equipped with the enzyme reverse transcriptase; HIV is retrovirus
provirus
integrated viral DNA from reverse transcriptase that does not leave the hosts genome
vaccines
harmless variants or derivatives of pathogenic microbes that stimulate immune response
viral horizontal transmission
a plant is infected from an external source of the virus
viral vertical transmission
plant inherits a viral infection from a parent
viroid
circular RNA pathogenic molecules; only several hundred nucleotides long, that infect plants
prions
infectious proteins which appear to cause a number of degenerative brain diseases
prion transmission
misfolded protein that induces the correct protein upon contact to assume the incorrect shape
transformation
uptake of naked, foreign DNA from the surrounding environment in bacteria capable of natural transformation or induced
transduction
phages carry bacterial genes from one host cell to another after incorrect insertion of bacteria DNA into phage
conjugation
direct transfer of genetic material between a bacteria with F factor and another bacteria
plasmid
small, circular, self replicating DNA molecule separate from bacterial chromosome
episome
temperate viruses; genetic element that can replicate either as part or independently of bacterial chromosome
transposable element
unlike plasmid or prophage, always part of chromosomal or plasmid DNA
insertion sequence
contains only the single gene transposase which recognizes inverted repeats
transposon
includes inverted repeats with transposase gene which sandwiches another or multiple genes
bacterial operator
controls the access of RNA polymerase to the genes near the promoter
operon
the operator, the promoter, and genes they control
bacterial repressor
binds to the operator and blocks attachment of RNA polymerase to the promoter
corepressor
small molecule that cooperates with a repressor protein to switch an operon off
DNA Polymerase III
synthesizes DNA in leading and lagging strand for bacteria
DNA Polymerase I
removes RNA primers and fills in with DNA
bacteria chromosomes
most bacteria contain circular chromosomal DNA and one chromosome with few million bp
bacterial OR
several thousand different genes and one bidirectional origin of replication
bacterial DNA compaction
DNA must be compacted 1,000 fold
bacterial primosome
DNA helicase+primase
bacterial replisome
2 DNA polymerase holoenzymes+primosome
