selective breeding, cloning and genetic engineering (paper 2) TOPIC 6 Flashcards
what else is selective breeding known as
artificial selection
define selective breeding
the process by which humans breed plants and animals for particular characteristics
what does selective breeding ensure
that the genes for the chosen specific characteristic remain in the population
how long have humans been doing selective breeding
thousands of years
give some examples of desired characteristics
- disease resistant crops
- animals that produce more meat or milk
- domestic animals with a gentle temperment
- large or unusual flowers
what does selective breeding provide evidence for
evolution - shows how significant variation is in a (relatively) short period
describe the process of selective breeding
- select parents with desirable characteristics
- breed together
- select offspring with desirable traits and breed again
- over many generations
what are the three main problems with selective breeding
- leads to reduction in the gene pool
- inbreeding results in health problems
- new diseases and defects can occur
explain how reduction of the gene pool is an issue from selective breeding
- reduces the number of alleles in the population as chacateristics aren’t chosen
- if conditions change and new characteristics are needed = problem from lack of variation, cannot cope with change
explain how inbreeding is an issue from selective breeding
- results in very little variation in the population
- can cause inherited defects to be passedd through to offspring
explain how new dieases and defects can occur from selective breeding
- due to reduced genetic variation in a population
- certain disadvantageous alleles are more common
- organisms struggle to cope with diseases
what is meant by the term genetic engineering
the process involving modifying the genome of an organism by introducing a gene from another organism to give it a desried characteristc
how have plant crops been genetically engineered
to be resistant to diseases or to produce bigger better fruits
how have bacterial cells been genetically engineered
to produce useful substances such as human insulin to treat diabetes
what are organisms which have been given genes from other organisms called
transgenic
descirbe the process of genetic engineering
- enzymes are used to isolate and ‘cut out’ the required gene from an organism
- the gene is then inserted into a vector (plasmid or vector) using more enzymes
- the vector is then used to insert the gene into the required cells
- genes are transferred to the cell at an early stage of development
- as the organism grows it developes with the new desired characteristics from the other organism
give an example of genetic engineering
- jellyfish gene to make crop glow when lacking water
- GM plants are more resistant to herbicides
what are the benefits of genetically modified organisms
- nutritional value of crops are improved
- increased crop yield helps global food security
- crops have longer shelf life
- crops are resistant to herbicides so fields can be treated
what are the risks and issues with genetically modified organisms
- new trains could cause health reactions
- concerns in decreasing biodiversity
- cross polination with non-GM crops = weeds
- we do not know the long term effects
- risk increase in allergies
- infertility can spread to wild crops
what is a clone
an individual that has been produced asexually and is genetically identical to the parent
how do you clone plants
taking cuttings
what is cutting in cloning plants
a form of asexual reproduction that has been carried out for hundreds of years
what is a more modern version of cuttings from plants
tissue culture, it is more expensive but allows you to make thousands of new plants from one small tissue
explain how plant cloning works (tissue culture)
- use a mixture of plant hormones to make a small group of cells from the plant you want to clone
- they then go on to produce a big mass of identical plant cells called a callus
- then useing a different mixtur eof hormones or conditions, you can stimulate each of these cells to form a small new plant
- guarenteing thousands of offspring with the desired characteristics
explain how plant cloning works (cuttings)
- small tissue sample taken from parent plant
- tissue is grown in agar with nutrients and plant hormones
- tiny identicle plantlets are formed
- plantlets grow on
describe embryo cloning in animals
- give fertility hormones to a top-quality cow so she produces many eggs
- fertilise these eggs using sperm from a really good bull
- these zygotes are then split into several embryos
- each embryo is transplanted into a host surrogate mothers
- the calves are born and genetically identical to their parents (not the surrogate mother)
what is adult cell cloning
when a whole new whole animal is produced from the cells of one singular other adult animal
describe adult cell cloning
- the nucleus is removed from an unfertilised egg cell (enucleated)
- at the same time the nucleus is taken from the adult body cell (eg skin cell) of the same species
- the nucleus from the adult cell is inserted into the empty egg cell
- the new egg cell is given a small electric shock to stimulate the dividing to form an embryo
- when the embryo has developed it is inserted into the uterus of an adult female and continues to develope
- when born it is genetically identical to the animal which nucleus was used
what is the name of the first large mammel to be adult cell cloned
dolly the sheep in 1996
what is the controversy around cloning - positive and negative
+ rare plants might be saved
+ allows mass production of genetically identicle offspring
+ can be quick
- reduction in gene pool
- morally wrong, organisms cannot consent
- may be used to clone humans
give two examples how genetic engineering has been use to treat human diseases
- insulin has been developed to treat diabetes
- engineer organisms to ave diseases so we learn how to treat them
