Genetics - Genetic Engineering and Cloning 180-183 Flashcards
what is selective breeding
when humans artificially select the plants or animals that are going to breed so genes for particular characteristics stay in the population
what is the process involved in selective breeding
4 points
1) select the ones that have the characteristics you’re after
2) breed them with each other
3) select the best offspring and breed them together
4) continue this process over several generations and the desirable trait gets stronger, eventually all the offspring will have the characteristic
how can selective breeding be used in agriculture
to improve yields - e.g. meat yields
what is the problem with selective breeding
3 points
1) it reduces the gene pool, the number of different alleles in a population is reduced - this is because the farmer keeps breeding organisms that are closely related, inbreeding
2) inbreeding increases the chance of organisms inheriting genetic defects
3) if there’s a new disease, as there’s not much variation in the population, so if one of the stock killed by the disease it’s likely the rest of them will to
what is genetic engineering
when you transfer a gene responsible for a desired characteristic from one organism’s genome to another organism, so they have that characteristic
how do you do genetic engineering
3 points
1) a useful gene is cut from one organism’s genome using enzymes and is inserted into a vector
2) the vector is usually a virus or bacterial plasmid
3) when the vector is introduced to the target organism the useful gene is inserted into its cells
what are some examples of genetic engineering
4 points
1) bacteria have been modified to produce human insulin that can be used to treat diabetes
2) crops have been modified to improve the size and quality of their fruit, or make them resistant to disease, insects and herbicides
3) sheep have been made to produce substances like drugs in their milk that can be used to treat human diseases
4) scientists are researching treatments for inherited diseases
what happens if the gene is transferred when the organism is at an early stage of development
the organism will develop with the characteristic coded for by the gene
what are the pros of genetic engineering
3 points
1) the characteristics chosen for GM crops can increase the yield, making more food
2) people living in developing nations often lack nutrients in their diets, GM crops can be engineered to contain the nutrient that’s missing
3) treating diseases
what are the cons of genetic engineering
4 points
1) some people say growing GM crops will affect the number of wild flowers and then insects growing around the crops, reducing biodiversity
2) not everyone thinks GM crops are safe
3) could create unplanned problems that are passed down to future generations
4) transplanted genes could get out into the environment - e.g. herbicide resistant gene could be picked up by weeds
how can plants be cloned
2 points
1) tissue culture
2) cuttings
what is a tissue culture
5 points
1) a few plant cells are put in a growth medium with hormones
2) they then grow in to new plants, clones of the parents
3) these plants can be made very quickly, in little space and be grown all year
4) used by scientists to preserve rare plants that are hard to reproduce naturally
5) also used by plant nurseries to produce lots of stock quickly
what is a cutting
2 points
1) gardeners take cutting from good parent plants then plant them to produce clones of the parent plant
2) these plants can be produced quickly and cheaply
how can animal clones be made from embryo transplants
3 points
1) sperm cells are taken from the ideal father and eggs cells from the ideal mother
2) sperm is then used to artificially fertilise an egg cell and the embryo that develops is then split many times to form clones before any cells are specialised
3) the cloned embryos can be implanted into lots of other cows where they grown into baby calves
what is adult cloning
4 points
1) involves taking an unfertilised egg cell and removing its nucleus
2) the nucleus is then removed from an adult body cells and inserted into the ‘empty’ eggs cell
3) the egg cell is then stimulated by and electric shock, which makes it divide like a normal embryo
4) when the embryo is a ball of cells it’s implanted into the womb of someone, it grows a clone of the original body cell
what are the issues around cloning
4 points
1) it causes a reduced gene pool
2) it’s possible cloned animals might not be as healthy as normal ones
3) some people worry humans might be cloned in the future, and if so there would be many failed attempts - e.g. children born severely disabled
what are the good things with cloning
2 points
1) can be used to help preserve endangered species
2) can lead to a greater understanding of the development of an embryo and of ageing and age-related disorders
