Methods of Cloning
Taking Cuttings- a shoot is placed in soil to grow roots. Whilst it is growing roots it is important that it doesn't dry out, to help with this some leaves are removed and the plant is kept in a clear plastic bag. Geraniums are cloned this way.
Tissue Culture- a small number of stem cells are cut out of a plant are placed on a nutrient agar to grow a group of cells. Tiny plantlets grow from these cells. Oil palm and banana plants are grown this way.
Disadantage of above: reduced gene pool
Embryo Splitting- eggs and sperm from the animal are brought together in a test tube. The embryo that grows is split and implated into a number of other animals' uterusus. All the offspring produced are identical to each other but not to the parents. Cattle are cloned this way.
advantages of embryo splitting: Hundreds of 'ideal' offspring can be produced every year from the best bull and cow. The original prize cow can keep producing prize eggs all year around
disadvantages of embryo splitting: The same alleles keep appearing (and many others are lost), so there's a greater risk of genetic disorders, and a disease could wipe out an entire population if there are no resistant alleles.
Genetic Engineering&GM Crops
Genetic engineering is about changing the DNA of a living thing to change its characteristics .
GM Crops are genetically modified crops. Crops can be given extra genes for new and useful characteristics. Characteristics include pest, frost, disease, herbicide and drought resistance and longer shelf life.
Advantages of GM crops
- Can increase the yield of a crop therefore making more food.
- People living in developing nations often lack nutrients in their diet, GM crops could be engineered to contain nutrients that are missing e.g. they're testing 'golden rice' that contains beta-carotene- lack of this could cause blindness
- GM crops are already being used without any problems
Disadvantages of GM crops
- Some people think growing GM crops will affect the number of weeds and flower (therefore wildlife) that usually lives in and around crops - reducing biodiversity.
- Not everyone is convinced that GM crops are safe, people are worried they may develop allergies to the food.
- A concern is transplanted genes may get out into the natural environment e.g. herbicide resistance may be picked up by weeds causing superweeds
An ordinary cell can make a new cell by simply dividing in two. The new cell has exactly the same genetic information as the parent cell.
1)X-shaped chromosomes have two identical halves, so each chromosome splits down the middle.
2)These form two identical sets of 'half chromosomes'
3)A membrane forms around each set and the DNA replicates itself to form two identical cells with complete sets of x-shaped chromosomes.
In Asexual reproduction there is only ONE parent, and the offspring has identical genes to the parent i.e. there is no variation between the parent and the offspring, so they're clones.
This involves taking the genetic material from an adult cell to make a new organism that is a clone of that adult. It has been done it mammals including sheep, horses and cats.
1) Take an egg cell and remove its genetic material.
2) A complete set of chromosomes from the cell of the adult you're cloning is then inserted into the 'empty' egg cell
3) This grows into an embryo and eventually into an animal that's genetically identical to the original adult.
The aim of therapeutic cloning is to produce spare body parts for disease sufferers without them being rejected by the sufferer's immune system.
A cloned embryo is created that is genetically identical to the sufferer and special cells (embryonic stem cells) that can become any cell in the body are extracted from it.
Adult Cell Cloning
1)The nucleus's from an egg cell and an adult body cell are removed.
2)The rest of the egg is then joined with the adult body cell nucleus
3)This creates an embryo
4)The embryo is then implanted into a surrogate mother to create an animal OR the stem cells are harvested to be used to treat disease.
Benefits&Risks of Cloning
- Animals that can produce medicines in their milk could be cloned.
- Animals that have organs suitable for organ transplantation into humans could be developed by genetic engineering and then cloned in the same way.
- The study of animal clones and cloned cells could lead to greater understanding of the development of the embryo and of ageing and age-related disorders.
- Cloning could be used to help preserve endangered species
- There is some evidence that cloned animals might not be as healthy as normal ones.
- Cloning is a new science and it might have consequences that we're not aware of
- People are worried that humans might be produced by cloning if research continues.