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Viruses show what kind of characteristics?
Living AND non-living
How do viruses reproduce?
Viruses can only reproduce within the living cells of another organism
What is the name given to the organism which the virus uses to reproduce?
What is the name given to a virus because it has to reproduce within the living cells of another organism?
Viruses _______ cause disease?
What do the viruses make use of from the host cell to make copies of themselves?
The cell's biochemical machinery
Does viral replication destroy the host cell?
Describe the structure of a virus
- A virus:
- is surrounded by a protective protein coat - capsid
- contains a nucleic acid core - either RNA or DNA
- some may also have an envelope, enzymes and/or fibres
How can viruses be transported?
By droplets, faeces, contact (blood or sexual) and animal bites
Describe the stages of viral replication
- The virus adheres to the host cell and thrusts its tail through the cell wall.
- The virus injects its DNA into the host cell
- The virus takes over the host cells biochemical machinery and replicates its own DNA using the host cell's nucleotides
- Each viral DNA molecule induces the formation of a protein coat and enters it
- The host cell bursts, destroying the cell, releasing many copies of the virus
What does the virus need to produce new viral particles?
The virus needs the host cell's nucleotides, ATP and amino acids
What must the virus do to the host cell before it can start replicating?
The virus must supress the cell's normal nucleic acid replication and protein synthesis