genetic engineering

process of genetic engineering

isolation / cutting / ligation / transformation / expression

genetic variation

genetic variation gives rise to differences in the phenotype

causes of genetic variation

sexual reproduction / mutation

mutation

change in genetic material / may occur in genes or chromosomes

causes of mutation

radiation , cigarette smoke , benzene , viruses

evolution

change in species or organisms over long periods of time

leads to the formation of a new species

brought about by natural selection in response to a change in the environment

who created theory of evolution

darwin and wallace

drawins and wallaces theory of evolutionn - natural selection

species have a high reproductive rate , producing large numbers of offspring

yet population numbers remain more or less constant over a long time

there is a high death rate among the offspring

this is due to competition for resources like food , shelter and a mate

variation occur among members of a species , making some individuals better suited to the conditions than others . many of these variations are inherited

evidence for evolution

the early embryos of fish amphibians reptiles, birds and mammals show many similarities

as development proceeds , changes occur giving rise to adult forms that are very different from each other .