'Action', in the sense used in this chapter, is what a geneticist is talking about when he mentions the 'phenotypic effect' of a gene. DNA has effects upon bodies, upon eye colour, hair crinkliness, strength of aggressive behaviour and thousands of other attributes, all of which are called phenotypic effects. DNA exerts these effects initially locally, after being read by RNA and translated into protein chains, which then affect cell shape and behaviour. This is one of the two ways in which the information in the pattern of DNA can be read out. The other way is that it can be duplicated into a new DNA strand. This is the copying that we discussed earlier.
