Viruses

2. Spherical bodies in the cytoplasm of cells that contain digestive enzymes
6. Occur when viruses reproduce, therefore allowing them to evolve
7. Allows the virus to attach to a host cell
8. The presence of receptors on the virus means that they only bind to _______ host cells
11. An enzyme involved in the synthesis of new viral DNA
14. Directs the synthesis of a special enzyme called reverse transcriptase
15. A type of virus
16. Made up of simple repeating protein units known as capsomeres
17. Used as a template for new viral proteins and to synthesis new viral RNA genome.
19. A substance that speeds up a reaction without being changed itself
21. ________ proteins prevents viral mRNA from being produced, and therefore stops the virus from becoming lytic
22. The _____ envelope covers the genetic material and protein coat

1. Formed through the condensation reaction of nucleotides
3. Such as x-rays and ionising radiation increases the rate of mutation
4. Most scientists class viruses as 'obligate intracellular _________'
5. The smallest of all the microorganisms
9. The route of infection where viruses are non-virulent
10. Viruses that infect bacteria
11. A type of virus whose genetic material whose viral DNA in incorporated into the host cells DNA
12. New viral material that has been synthesised leaves the host cell through __________
13. 'Cell suicide' - destruction of the contents of the cell
18. Viruses cause the symptoms of disease through the _____ of the host cell
20. When new virus particles start to invade other cells, the virus is said to be ________