Cloning and evolution Flashcards
clones
genetically identical individuals produced naturally by asexual reproduction or artificially
animals
cloned using embryo transplants and adult cell cloning
plants
cloned using cuttings or tissue culture
tissue culture
small groups of cells extracted from plant and put in growth medium
division eventually results in formation of clone of parent plant
tissue culture advantages
quick, space efficient and time independent
important for commercial use in nurseries and preservation of rare species
cutting method
branch cut off from parent plant + hormones used to encourage roots to grow, cut then planted
cuttings produce clone of parent plant
allows large number of plants with favourable characteristics to be grown cheaply and quickly
adult cell cloning
unfertilised egg cell taken and nucleus removed
egg cell injected with nucleus from adult body cell belonging to animal being cloned
electric shock given to egg cell to stimulate division
implanted into surrogate mother when it has grown into a larger ball of cells
embryo will continue to develop into womb of surrogate
embryo transplants
developing embryo split up into smaller groups of cells before differentiation to give many smaller identical embryos, which can be put into host mother
variation
individuals in a population have different combinations of genes
adapted animals may be more likely to survive
evolution theories controversies
genes had not been discovered at the time
was unable to explain genes being passed down generations
scientists regarded Darwin’s evidence as inconclusive
challenged belief that God created natural world
lamarck’s theory
proposed changes in an organism over its lifetime were passed down to offspring
known as “theory of inheritance of acquired characteristics”
speciation
geographical isolation
due to diff environments, natural selection operated differently
eventually leads to genetic divergence until they no longer produce fertile offspring
then become two diff species
