Genetics is the study of heredity and variation
i.e. the tndency of offspring to resemble their parents, and also to differ
from one another and their parents. It was founded on a basic set of principles
and analytical procedures that arose from the work of Gregor Mendel.
For thousands of years, livestock and plant crops
have been bred by humans to produce desirable traits. Until Mendel's work,
nothing was understood about the underlying mechanism for the inheritance
of characteristics. The common theory prior to that proposed by Mendel,
was one involving "gemmules" in which particles were passed from the parent's
organs to the blood, and finally to either the egg or the sperm. The particles
from the parents were thought to mix or blend in the offspring to produce
individuals with characteristics intermediate between those of the parents.
This theory, known as "blending inheritance", did not however agree with
experimental observations in which the offspring were not always intermediate
in character between the parents. It also presented problems when looked
at from an evolutionary perspective.
Mendel proposed instead a theory of "particulate
inheritance" in which the characteristics of an organism are determined
by discrete units (later called "genes") which are passed from parent to
offspring. This theory is supported by experimental observation. Genes
were later found to be distinct regions on DNA molecules which carry the
genetic code for the production of proteins.
Genes are central to genetic studies at every
level, from molecular to evolutionary genetics. An organism's characteristics
are the result of the interaction between its genes and its environment.
The genes provide a set of instructions while the environment provides
the raw materials.
The majority of the work done in genetics involves
the manipulaton of the genetic code of organisms, either by classical genetic
techniques (crossing individuals in order to produce offspring with the
required characteristics) or by molecular genetic techniques (using recombinant
DNA technology to directly alter the genetic code). Genetics has a profound
effect on all our lives. Genetic techniques are used most widely in agriculture
( for example to produce plant crops with higher yields or resistance to
pests) and in medicine (studying the genetic basis of diseases and, hopefully,
soon developing gene therapies).
Governments and industry are investing in genetic
research. The most notable project currently underway is The Human Genome
Project. Many scientists in laboratories all around the world are cooperating
with one another in order to produce a map of the entire human genome.
This will undoubtedly lead to a better understanding of, for example, inherited
diseases.
Genetics is one of the most rapidly advancing
areas of science, I hope this introduction has given some basic idea of
what it is and where it developed from.
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