Viruses Flashcards
Viruses
Organic particles that exist on border of considered life
How big are viruses and how do we view them
20-400 nm
Electron microscope
Acellular
Don’t have cells
Characteristics of life viruses have
Can evolve, reproduce, interact with environment
Characteristics of life that viruses don’t have
Don’t contain cells, grow, use nutrients or release waste
Capsid
Protein capsule that surrounds nucleus acid/enzymes of virus
Made of repeating proteins
Core
Inside of capsid
Contains salt solution like cytoplasm
Nucleic acid
Hereditary material used to make new viral proteins inside host
Contains DNA or RNA (not both)
DNA
Benefit of being more stable + allowing more complex genetics
RNA
Benefit of making proteins easier + having higher mutation rate
Mutation rate
Makes viruses more adaptable
Enzymes
Used for helping viruses replicate in cell
Transcriptase
Enzymes which decode viral RNA to make viral proteins
RNAses
Enzymes that destroy host RNA so viral proteins have higher priority
Polymerases
Make copies of RNA or DNA from viral template so viral replication can occur
Envelope
Cell membrane that surrounds capsid
Taken from host cell
Surface proteins
Part of virus to identify/ invade host cells
Antigens
Result of surface proteins triggering an immune response
Antibody generator
Bacteriophages
Viruses that only infect bacterial cells
Have unique shape
Head/sheath of bacteriophages
Head- capsid containing nucleic acid
Tail- contains sheath/attachment site for injecting nucleic acid into bacteria
Viral replication pathway
A way which a virus duplicates it’s nucleic acid
Starts when virus interacts with host cell
4 steps of viral replication pathway
Entrance/assembly
Synthesis
Assembly/packing
Release
Entrance
The injection of nucleic acid or entire virion into host cell
Synthesis
Hijack host cell organelles
Use host cells for protein synthesis/nutrients
Assembly
Brings together capsid proteins, nucleic acid, and sometimes enzymes
Release
Consists of either lysis or budding of the virions
Lysis
Rupturing of host cell + release of new virus
Results in 100-300 new virions
Virulent
Virulent
Cause damage to cells/organs
Budding
Produces virions that bud from host cell, taking cell membrane to form envelopes
Pathway that doesn’t perform lysis
Lysogenic
Prophages
Viral nucleic acid that inserts into host DNA + acts as extra set of genes
Temperate
Viruses that use lysogenic cycle
Ex. Herpes
Retroviruses
RNA viruses that carry enzyme called reverse transcriptase to convert RNA into DNA
Ex. HIV
Latency
Stage prophage enters after inserting into DNA
Does not produce new virions