Virus (H&D 003) Flashcards
What is the definition of a virus
Viruses are obligate intercellular parasites, a poison or venom that is able to self-replicate via resources from their host cell
What are the three general characteristics of a virus
Size, structure and metabolism and host range
What is the size of a virus
Very small
What is the metabolism and structure of a virus
Acellular, do not carry any MRS GREN processes, lack enzymes and produces waste products
What is the host range of a virus
The range of a virus’s infection, dependent on the receptors of the host cell and the virus
What are the four structures of the virus
Genome, capsid, envelope and spikes
What is the function of the genome
A genome is a nucleic acid, it can either be RNA or DNA
What is the function of the capsid
A protective coat of the virus in which is made of protein, consists of tiny sub-units called capsomeres
What is the function of the envelope
A membrane, some viruses have this
What is the function of spikes
Enables the virus to attach itself to the surface receptors of the host cell
What effects does it have on a host cell when affected by a virus
Cell death (lysis), viral particles build up in the host cell disrupting function, viruses are released in short bursts (persistent infection) or nothing happens for a period of time until a certain stimulus is triggered to initiate the lytic cycle (latent infection)
What is the definition of latency
The ability of a pathogenic virus to lie dormant within a cell
What is the definition of bacteriophage
A virus that specifically infects bacteria
What is the definition of lytic cycle
The normal process of viral reproduction involving penetration of the cell membrane, nucleic acid synthesis, and the lysis of the host cell
What is the definition of the lysogenic cycle
A form of viral reproduction involving the fusion of the nucleic acid of a bacteriophage with that of a host, followed by proliferation of the resulting prophage
Why do viruses replicate
In order to create new infection virions to infect other cells of the body.
What are the four stages in the lytic cycle
Attachment, uncoating, component biosynthesis, Assembly and release
What occurs in attachment in the lytic cycle
The spikes of the virus attach to the surface receptors of the host cell (Endocytosis)
What occurs in uncoating of the lytic cycle
The capsid is removed in which nucleic acids are released
What occurs in component biosynthesis in the lytic cycle
Genome is replicated and translated to make new viral components, enveloped viruses are prepared in the cell membrane ready to be released
What occurs in assembly and release in the lytic cycle
Viral components are fused together to form a virus, naked virus lyse the cell to be released whereas enveloped viruses push through the prepared cell membrane
What is the difference between lytic and lysogenic viral infections
Lysogenic viral infections have an extra step called integration
What is the integration in lysogenic viral infections
The viral infection is integrated with the host genome for a long period of time (latent infection)
