Viruses

• ●      NOT alive as they don’t do any of MRS C GREN
• ●      Very small, smaller than bacteria;
• ●      they have no cellular structure but have a protein coat
• ●      they contain one type of nucleic acid, either DNA or RNA.
• ●      they can reproduce only inside living cells;
• ●      they infect every type of living organism, they cause disease so are pathogens
• ●      they have a wide variety of shapes and sizes;

  eg tobacco mosaic virus causes discolouring of the leaves of tobacco plants by preventing the formation of chloroplasts, the influenza virus that causes ‘flu’, the HIV virus that causes AIDS, and who can forget COVID!