Gregor Mendel was an Austrian Monk who discovered the basic principles of heredity through
experiments in his garden. He examined the inheritance of clear cut alternative traits in pea plants, such as
purple versus white flowers or yellow versus green seeds. Mendel's observations became the foundation
of modern genetics and the study of heredity, and he is widely considered a pioneer in the field of
genetics. Mendel’s laws are based on the hypothesis that observable traits are determined by units of
inheritance that are visible to the naked eye.
Four general themes emerge from Mendel’s work:
1. The first is that variation, as expressed in alternative forms of a trait is widespread in nature. This
provides the raw materials for the continuously evolving variety of life we see around us.
2. Second, observable variation is essential for following genes from one generation to the next.
3. Third, variation is not distributed solely by chance, rather it is inherited according to genetic laws
that explain why like begets both like and unlike.
4. Fourth, the laws Mendel discovered about heredity apply equally well to all sexually reproducing
organisms, from protozoans to peas to people.
Artificial selection: The breeding of plants and animals to produce desirable traits. Organisms with the
desired traits, such as size or taste, are artificially mated or cross-pollinated with organisms with similar
desired traits. Artificial selection was the first applied genetic technique.
Domestication: the process of hereditary reorganization of wild animals and plants into domestic and
cultivated forms according to the interests of people. In its strictest sense, it refers to the initial stage of
human mastery of wild animals and plants. The fundamental distinction of domesticated animals and
plants from their wild ancestors is that they are created by human labour to meet specific requirements or
whims and are adapted to the conditions of continuous care and solicitude people maintain for them.
Domestication has played an enormous part in the development of humankind and material culture. It has
resulted in the appearance of agriculture as a special form of animal and plant production. It is precisely
those animals and plants that became objects of agricultural activity that have undergone the greatest
changes when compared with their wild ancestors. For example, dogs slowly arose from wolves.
Nature refers to the human traits one gets biologically through their parents and cannot be altered or
changed in any way. Nature vs.Nurture is a debate. Nature (heredity, genes) vs.Nurture
(environment) It is debate whether we are influenced by genes or the our surroundings.
Discrete, or discontinuous, traits are controlled by a small number of genes, often only one. These genes
generally have two alleles. For instance, Mendel's pea seeds had two alleles for shape: smooth or
wrinkled. An example of human alleles is seen with freckles; each person has a freckled or non-freckled
allele. Discrete units of inheritance are alleles of genes.
Pure-breeding lines means that the parents will also pass down a specific phenotypic trait to their
offspring. Remember that a phenotype is the outward appearance of something. True bred organisms will
have a pure genotype (genetic expression of a trait) and will only produce a certain phenotype.
Hybrid: known as cross breed, is the result of mixing, through sexual reproduction, two animals or plants
of different breeds, varieties, species or genera. A hybrid organism is one that is heterozygous, which
means that is carries two different alleles at a particular genetic position, or locus.