Types of reproduction
- Asexual reproduction only requires one parent.
- There is no fusion of gametes in asexual reproduction.
- Clones are produced by asexual reproduction.
- Clones are identical copies of one parent.
- Sexual reproduction is the fusion of gametes from two parents.
- Variety in the offspring is acheived with sexual reproduction as the mixing of genetic information creates a variety in the offspring.
Genetic and environmental differences
- Differences in the characteristics of individuals of the same kind may be due to:
- differences in the genes they have inherited.
- the conditions in which they have developed.
- a combination of both these genetic and environmental causes.
- Clones may have some differences due to environmental causes.
- Plant clones can be made quickly and effectively by taking cutting from mature plants and growing them.
- Tissue culture is a new method of cloning and is more expensive. Used to reproduce large numbers of a rare or top quality plant.
- Animals can be cloned by transplanting cloned embryos.
- Clones are formed by asexual reproduction.
- Genetic engineering is used to transfer a gene from one organism to another.
- Enzymes are used to 'cut out' a gene from a human chromosome and then insert it into a baceria cell. e.g. to produce large quantities of insulin to treat diabetes.
- Genes can be transferred to the cells of animals and plants at an early stage in their development.
Making choices about technology
There are many advantages and disadvantages in using cloning and genetic engineering:
- Cloning cattle can produce herds of cattle with useful characteristics.
- Adult cell cloning may be used to make copies of the best animals e.g. race horses.
- GM crops include ones that are resistant to herbicides or to insects.
- Several medical drugs have been produced by genetic engineering, such as insulin and antibodies.
- Insects which are NOT pests may be affected by GM crops.
- Many people worry about the effect of eating GM crops on human health.
- Many poeple argue about whether or not cloning and genetic engineering are ethical. What will be the long term effects? Will we create new organisms that we know nothing about? Are these processes ethically correct?