Bio Chapter 33

• Capsid is a shell that surrounds the nucleic acid
• Nucleocapsid is a capsid and nucleic acid together
• an envelope is not found in all viruses but usually is a modified piece of the host cell membrane
• spikes are found on both naked and developed viruses. Project from either the nucleocapsid or envelope
• Naked viruses consist only of a nucleocapsid and NO envelope
• A virion is a fully formed virus able to establish infection in a host
• Capsomeres are the building block of a capsid
• Helical capsid is a rod-shaped capsomere that forms a continuous helix around the nucleic acid
• Icosahedral capsid is a three-dimensional , 20-sided figure with 12 evenly spaced corners
• Complex capsid is a prism shaped head with multiple tails and attack the bacteria.
• Bacteriophage is viruses that only infect the bacteria
• non enveloped virus is a virus that does not have a capsid and is not surrounded by a lipid bilayer
• enveloped virus is a virus that has a lipid envelope and is surrounded by a protein coat
• The viral envelope is made up of spikes that allows it to attach to the host cell
• A genome is the full complement of DNA and RNA carried by a cell
• Viruses contain either DNA or RNA but not both
• Inside the envelope or capsids are where proteins are
• HIV virus is complex because it reverse transcriptase the RNA
• General phases in the life cycle of animal viruses are adsorption, penetration, uncoating, synthesis, assembly, or release from the host cell
• Adsorption invasion happens when a virus comes in contact with a host and absorbs to receptor sites on the cell membrane
• Host range is when a virus can invade its host cell only though making an exact fit with a specific host molecule
• restricted host range: Hepatitis B only infects liver cells of humans
• Moderately restrictive host range: poliovirus infects intestinal and nerve cells of primates
• Broad host range: rabies virus infects various cells of all mammals
• Penetration is when the virus gets swallowed by the host cell
• Endocytosis: an entire virus is engulfed by the cell and enclosed in a vacuole or vesicle
• Uncoating: the removal of the capsid from the genetic information
• RNA viruses replicate in the host cytoplasm
• DNA viruses replicate in the host nucleus
• Synthesis: Replication and protein production
• In order for a virus to get multiplicated, the dna needs to get replicated
• Replication > DNA > transciption > RNA > translation > protein
• Exocytosis: how the virus eventually gets outside the envelope
• Cells can go through organelle or cytoplasm damage
• inclusion bodies: compacted masses of viruses or damaged cell organelles in the nucleus or cytoplasm
• Syncytia: fusion of multiple host cells into single large cells containing multiple nuclei.
• Viral DNA enters the nucleus > transciption occurs in 2 phases > RNA moves into cytoplasm > Viral mRNA translates into structural proteins > Viral DNA replicated in the nucleus > Viral DNA & protein assembled into mature virus in nucleus > Viral DNA can insert into host cell
• Bacterial viruses infect bacteria, not humans
• DNA viruses have double stranded DNA, while RNA viruses have either ssRNA (retroviruses) or dsRNA.
• Bacteriophage: often makes bacteria they infect more pathogenic for humans; parasitize every known bacterial species