2)Biotechnology and gene technologies.

2)Clones in nature A clone are genes, organisms or cells that carry the identical genetic material because they are derived from the same DNA. Cloning can be produced by both artificially and naturally. Twins – zygote splits in two, Plants- produce runners (new plants that are clones) and bacteria – divide by binary fission and are all the same providing no mutations. Advantages of asexual reproducing (plants/bacteria): quick process so can take advantage of resources in environment, can be completed if sexual reproduction fails or cant take place, offspring have all genetic makeup to survive in environment (most desirable alleles). Disadvantages of asexual reproduction: no genetic variation so weakness will be in parent, so if environment changes then they will all be equally susceptible. Vegetative propagation - production of structures in an organism that can grow into individual organisms, and are clones of parent. E.g English Elm trees can asexually reproduce when parent plant has been damaged. New growth forms in root suckers (or basal sprouts) within 2 months of destruction of main tree. They grow from meristem tissue in the roots so are close to the ground when least damage would have occurred. Advantage of this vegetative propagation: help the elm grow as they spread out around the trunk, when the tree is cut e.g felled in coppicing cycle the suckers grow in a circle around it (clonal patch) and will keep expanding as much as the resources allow. Disadvantages of this vegetative propagation: when Dutch Elm tree disease spread through Europe, all the Elms got the disease which was carried by an infected beetle. Although the root suckers would then be a response to the main tree dying, they were still a direct clone of the parent tree so when they hit 10cm in diameter they become infected and die. There is no genetic variation between the population, so natural selection cannot occur. Other examples of vegetative propegation: – - POTATOES: specialised underground stems become swollen with nutrient molecules, forming tubers, from which the new plants grow – -ONION, DAFFODILS: condensed shoots with very leafy stems and fleshy leaves bases(BULBS)form, containing nutrients; buds at the sides develop into new bulbs. – -STRAWBERRY: specialised stems (runners) grow along ground from parent plant and at the tips they form roots and shoots.

2)Artificial clones and agriculture Two main methods of artificial propagation include: 1)taking stems – selection of stems are cut between leaf joints (nodes) and treated with plant hormones to encourage growth and are direct clones of parent plant. E.g. in geraniums.. 2)Grafting- shoot selection of woody plant (fruit tree or rosebush) joined to already growing root (rootstock). Graft grows and genetically identical to parent plant, but rootstock in normally different. But, these methods cannot be used to produce huge numbers very easily as some do not reproduce well. More modern methods uses plant tissue culture to generate huge amounts from very little plant material. Tissue culture also has the added advantage that these stocks known to be disease free. Micropropagation by callus tissue culture (this is how many household plants are produced, such as orchids.) 1) small piece of tissue taken from plant to be cloned, usually from shoot tip (explant). 2) explant is placed of nutrient growth medium. 3) cells in tissue divide, but not differentiate. Instead from mass of undifferentiated cells, Callus. 4) after few weeks single callus cell can be removed and placed onto growth medium containing hormones to promote shoot growth. 5) few more weeks, shoots transferred again onto different growth medium containing root growth hormones. 6)growing plants transferred to greenhouse to be acclimatised and grow further before being placed outside. Advantages of cloning in agriculture: farmers know what features the plant will have as it has been cloned straight from parent plant. Farmers costs are reduced because all crop is ready for harvest at same time. Faster than selective breeding as huge numbers can be created from small number of plants. Disadvantages of cloning in agriculture: all plant susceptible to new pest or infection.

2)Cloning animals Cloning in animals can occur with the splitting of a zygote – twins. However, there are two possible ways to artificially clone animals... 1) splitting embryos : by splitting an embryo so they can produce genetically identical organisms. First primate cloned with this method was a rhesus monkey called Tetra. 2) Nuclear transfer : differentiated cells from adult taken and nucleus place in a cell where it has been removed prior. Then goes through development with the chosen nucleus. First animal was dolly the sheep in 1996 and took 277 attempts. Non-reproductive cloning in the method to clone cells to generate more cells, such as tissues and organs to replace those that are damaged. ADVANTAGES OF NRC: 1)will not be rejected by immune response as genetically identical.2) Cloning and cell culture techniques could put end to waiting for donor. 3) Cloned cells can be anything because they are totipotent(undifferentiated).4)less dangerous that major ops such as heart transplant. Many possibilities for NRC: 1)regeneration of heart cells after heart attack. 2) repair of nervous tissue after disease such as MSU. 3)repair of spinal cord after paralysed by accident that caused broken back/neck. These are often referred to as therapeutic cloning. Ethic resistance as objection to human embryos being used, scientific concerns that not enough is known about how cloned cells with behave over long period of time. AdvantagesDisadvantages High value animals, dairy cows, can be cloned in large numbersAnimal welfare. E.g. Some meat chickens can’t walk. Rare animals cloned to preserve speciesNo variation between them so unlikely to cope with changing environment GM animals quickly reproduced. E.g. Sheep with medicine in them Unclear if they remain healthy for long time. Dolly had cancer at 6, premature ageing due to cloning.