Viral genetics Flashcards
ssDNA viruses
Often small
Can be +, -, or ambisense
dsDNA viruses
Have the largest and most complex genomes
Most stable genome
DNA dependant DNA polymerase have high fidelity
+ssRNA viruses
Size limited due to RNA fragility
Higher mutation rate because RNA dependent RNA polymerase are more error prone (except coronaviruses)
Majority of plant viruses
The majority of plant viruses are which type?
+ssRNA
-ssRNA viruses
More genome diversity than +ssRNA
Gene expression and genome replication is harder
Often segmented to increase stability
Must bring its own RNA polymerase
Which virus is segmented?
-ssRNA
Which viruses must bring its own polymerase?
-ssRNA
Reverse transcription
2 +ssRNA to 1 dsDNA
Very error prone = rapid genetic variation
2 +ssRNA copies promotes recombination
dsDNA integrates into host genome for lifelong infection
Why don’t we need to worry about bacteriophages?
Genome not recognizable and decidable by our cells
Viral genome compression
Selective pressure to maximize genetic capacity and minimize genome size
Dense genome increases replication rate compared to host
Gel electrophoresis
Nucleic acids are negative
Useful for analyzing intact genomes, segmented genomes, and sequencing
PCR
Allows detection of minuscule amounts of viral nucleic acids
Use RT-PCR for RNA viruses
Transfection
Infection of cells by nucleic acids alone (use plasmids of each gene)
Transduction
Transfer of genome from packaging cell to the target cell
Strain
Same viruses but different isolates (flu from two countries)
