46-Intro to Medical Microbiology 2 Flashcards
What is a virus
Nucleic acid with protein coat Can have a lipid envelope Not alive, depend entirely on host cell Not metabolically active Smaller than bacteria
What is a bacteriophage
Virus that infect and replicate in bacteria
DNA in a virus
double stranded, replicates in nucleus
RNA in virus
Single stranded, replicate in cytoplasm
Can be positive or negative
Positive sense RNA
Ready for translation
Negative sense RNA
Requires complementary strand synthesis
Lipid envelope
On some viruses
Non enveloped. Viruses are particularly hardy like norovirus
virion
Individual virus particle
capsid
Proteins associated with nucleic acid
capsomers
Individual proteins making up capsid
Spike proteins
Specific binding or enzymatic functions
Emerging from capsid of naked virus or membrane of enveloped virus
HIV
Reverse transcriptase during replication
Shape of capsomers
Helical or spherical (icosahedral)
Virus life cycle at cell level
Adsorption Penetration and uncaring Synthesis Assembly release
Virus life cycle at organisms level
Attachment Spread Replication Evasion transmission
adsorption
Interactions between viral proteins and specific host proteins
Have particular tropism
Penetration and uncoating
Need to get through cytoplasmic membrane to cytoplasm/nucleus for replication
Enveloped-fuse membrane
Naked-lyse
Synthesis and replication
+sense RNA ready to translate
-sense RNA need to generate +sense first
DNA transcribe mRNA
Assembly of virions
Helical-capsid proteins form around nucleic acid
icosahedral- capsid assembles and nucleic acid threaded in
release
Enveloped-membrane budding
Naked-cell lysis
influenza
Enveloped negative sense RNA with 8 genome segments
Adsorption of flu
hemagluttinin binds sialic acids
Uncoating of flu
Membrane fusion
Synthesis of flu
Happens in nucleus, use RNA dependent RNA polymerase to make +mRNA, goes to cytoplasm to make proteins and -mRNA
Assembly and release of flu
Virus capsid buds out
Neuraminidase cleanse sialic acid to release virion