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Created page with "==Key Stage 4== ===Meaning=== A virus is a type pathogen that can infect individual cells in an organism. ===About Viruses=== : '..."
==Key Stage 4==
===Meaning===
A [[virus]] is a type [[pathogen]] that can [[Infection|infect]] individual [[Cell (Biology)|cells]] in an [[organism]].
===About Viruses===
: '''Viruses''' are made from a strand of [[DNA]] or [[RNA]] and a [[Protein Sheath|protein sheath]].
: '''Viruses''' cannot reproduce outside a [[host]] [[Cell (Biology)|cell]] so they are not considered to be [[alive]].
: When a '''virus''' comes in contact with a target [[Cell (Biology)|cell]] it attaches itself to the [[Cell Membrane|cell membrane]] and then injects its [[DNA]] (or [[RNA]]) into the [[Cell (Biology)|cell]]. Once this is done the [[DNA]] causes the [[Cell (Biology)|cell]] to start making copies of the [[virus]]. When millions of copies have been made they burst out, killing the [[Cell (Biology)|cell]]. These millions of [[virus]]es can then go on to [[infection|infect]] other [[Cell (Biology)|cells]].
: Different [[virus]]es can only attach themselves to certain types of [[Cell (Biology)|cell]], so they can all have very different effects on the [[organism]] depending on which type of [[Cell (Biology)|cell]] they [[infection|infect]].
===Examples===
: [[Measles]] is a [[disease]] caused by a group of [[virus]]es called [[Morbillivirus]]es. It can cause a [[rash]], blindness and [[brain]] damage.
: [[AIDS]] is a [[disease]] caused by a [[virus]] called [[HIV]]. The symptoms are a weakening of the [[Immune System|immune system]] which leads to other [[infection]]s.
: [[Tobacco Mosaic Virus]] is a [[virus]] which causes [[Tomato Plant]]s and [[Tobacco Plant]]s to grow slowly.
===Meaning===
A [[virus]] is a type [[pathogen]] that can [[Infection|infect]] individual [[Cell (Biology)|cells]] in an [[organism]].
===About Viruses===
: '''Viruses''' are made from a strand of [[DNA]] or [[RNA]] and a [[Protein Sheath|protein sheath]].
: '''Viruses''' cannot reproduce outside a [[host]] [[Cell (Biology)|cell]] so they are not considered to be [[alive]].
: When a '''virus''' comes in contact with a target [[Cell (Biology)|cell]] it attaches itself to the [[Cell Membrane|cell membrane]] and then injects its [[DNA]] (or [[RNA]]) into the [[Cell (Biology)|cell]]. Once this is done the [[DNA]] causes the [[Cell (Biology)|cell]] to start making copies of the [[virus]]. When millions of copies have been made they burst out, killing the [[Cell (Biology)|cell]]. These millions of [[virus]]es can then go on to [[infection|infect]] other [[Cell (Biology)|cells]].
: Different [[virus]]es can only attach themselves to certain types of [[Cell (Biology)|cell]], so they can all have very different effects on the [[organism]] depending on which type of [[Cell (Biology)|cell]] they [[infection|infect]].
===Examples===
: [[Measles]] is a [[disease]] caused by a group of [[virus]]es called [[Morbillivirus]]es. It can cause a [[rash]], blindness and [[brain]] damage.
: [[AIDS]] is a [[disease]] caused by a [[virus]] called [[HIV]]. The symptoms are a weakening of the [[Immune System|immune system]] which leads to other [[infection]]s.
: [[Tobacco Mosaic Virus]] is a [[virus]] which causes [[Tomato Plant]]s and [[Tobacco Plant]]s to grow slowly.