Hidden World Flashcards
(20 cards)
What are acellular microbes
Viruses
What is the theory of RNA world hypothesis
Earliest cells were RNA surrounded by liposomes
Im the great oxygenation event, what led to increase in oxygen in atmosphere
Evolution of photosynthetic Cyanobacteria which increased O2
levels
How did insoluble iron oxide form
Iron which was prevalent in thr Rocks which reacted with oxygen to for, insoluble iron oxide
Who was first person to observe microbes
Antoine van Leeuwenhoek
Used hand made lenses
What r satellites
Subviral infectious agents composed of nuceic acid and protein that need helper virus to replicate
Viroids
Non translated ssRNAs lack protein and infect plants
Prions
Infectious proteins
Cause spongiform encephalopathies
What are capsids made of
Protect genetic material and aid in transfer between host cells
Protein subunits called protomers
Helical icosahedral or complex
Describe viral replication cycle
Attachment via binding specific host receptor
Penetration and uncoating of nucleocaspid
Transcription and translation of viral proteins
Replicating viral genome
Assembly of viral progeny
How do dsDNA viruses replicate
Usually in host cell nucleus using host DNA polymerase
dsDNA > mRN>protein
How do ssD A viruses replicate
Must convert ssDNA to dsDNA first
How do RNA viruses replicate
Use virally encoded enzymes to replicate genome
DsRNAand -ve ssRNA carry RNA dependent RNA polymerase in capsid
How are virions released from enveloped viruses
Budding
Viral proteins placed in host cell membrane
Nucleocaspid may bind to viral proteins
Endosymbiosis theory
Mitochondria originated from proteo bacteria and archaea cell
Chloroplasts from endosymbiotic Cyanobacteria and eukaryotic cell
What viruses DONT fit into the helix or icosahderal capsids
Pox viruses
Large bacteriophage - head (icosahdral)tail(helical)
Describe viral genome
Dna or RNA - not both
Single / double stranded , segmented , circular
Encode viral proteins , may also include regulatory elements
Describe attachment of virus to host cell
( Attachment )
Ligand on virion attaches to receptor on host
Viruses bind to specific tissue receptors ( tropism )
How do enveloped viruses enter host cell
Membrane fusion at cell surface or receptor mediated endocytosis and then membrane fusion in endosome
How do non enveloped viruses enter host cell
Receptor mediated endocytosis and uncoating or direct injection of nucleic acid
