B14: Variation Flashcards
what are the two types of variation
genetic and environmental (nature and nurture)
examples of characteristics affected by both genes and the environment
height and weight
what is natural selection
when organisms gain an advantage and are more likely to survive and breed.
natural selection:
-individual organism within a particular species show wide range of phenotype and genetic variation.
-those with characteristics most suited to the environment are more likely to survive and breed successfully.
-the alleles that have enabled these characteristics that survive are then passed to the next generation.
what is selective breeding used for
to breed the most desirable characteristics
what are some features selectively bred?
-disease resistance
-animals that produce more meat or milk.
-gentle nature in domestic animals
-large, bright flowers with heavy scent.
what are the problems with selective breeding
-reduces variation in alleles and individuals.
-inbreeding
what is genetic engineering
modifying the genetic material of an organism. this gives them a new and more desirable characteristic.
process of genetic engineering
-enzymes ‘cut out’ the required gene from an organism
-gene is inserted into a vector (virus or bacterial plasmid) using more enzymes.
-vector inserts gene into required cells
-genes transferred into cells at early stage of development. they grow and develop desirable traits
end process of genetic engineering in plants
genes inserted into meristem cells which produce identical clones of this plant.
why are genetically engineered bacteria and fungi useful
they can be cultured to make proteins from other organisms, e.g. insulin and human growth hormones
what are genetically engineering crops known as
GM crops. (genetically modified crops)
examples of a GM crop
-potatoes have been modified for more starch and more resistant to pests.
-rice plants can be flooded and still grow for 3 weeks
what is a clone
an individual that has been produced asexually and is genetically identical to the parent.
ways of cloning plants
-taking cuttings
-tissue culture
what is tissue culture
more expensive, but thousands of plants from one cutting.
process of tissue culture
-use a mixture of plant hormones to make a small group of cells from the plant you want to clone.
-they produce a mass of identical plant cells called a callus.
-then, using different hormones and conditions, you can stimulate the cells to form a tiny new plant.
why is tissue culture good
-creates many plants
-can preserve rare species
cloning animal techniques are called?
-embryo cloning
-adult cell cloning
how does embryo cloning work
-fertility hormones given to animal, she produces eggs
-fertilise these eggs using sperm from a father with desirable features
-fertilised embryo washed out the uterus, divided and cloned into multiple.
-embryos are inserted into different host mothers
pros of animal embryo cloning
-can transport desirable embryos around the world
process of adult cell cloning:
-nucleus removed from unfertilised egg
-nucleus taken from adult body cell of another individual.
-nucleus from adult cell inserted into empty egg cell
-new egg cell given electric shock, stimulating it to divide and form embryo cells.
-insert embryo into the womb of an adult female once it has developed into a ball of cells.
benefits of adult cell cloning
-large numbers of medically useful animals
-save animals from extinction
risks of adult cell cloning
-cloning of human babies (unethical)
-reduced variation
pros of genetical engineering
-potential to cure inherited disorders.
-improved growth rates
-increased crop value
-crops can grow in areas prone to drought
-crops produced are resistant to herbicides
concerns of genetic engineering
-insects could become pesticide resistant if they eat pesticide producing plants.
-GM plants and animals might spread into the wildlife and impact them (e.g. spread infertility)
-ethical worry over manipulating DNA, ‘designer children’
