What is Genetics?
Genetics is
a branch of biology concerned with the study
of genes, genetic variation,
and heredity in organisms. Though heredity had been observed
for millennia, Gregor Mendel, Moravian scientist and Augustinian friar working
in the 19th century in Brno, was the first to study genetics
scientifically. Mendel studied "trait inheritance", patterns in the
way traits are handed down from parents to offspring over time. He observed
that organisms (pea plants) inherit traits by way of discrete "units of
inheritance".
Genetics study of heredity in general and of genes
in particular.
Genetics forms one of the
central pillars of biology and overlaps with many other areas, such as
agriculture, medicines and biotechnology.
This term, still used today, is a somewhat
ambiguous definition of what is referred to as a gene.
Trait inheritance
and molecular inheritance mechanisms of genes are still primary
principles of genetics in the 21st century, but modern genetics has expanded
beyond inheritance to studying the function and behavior of genes. Gene
structure and function, variation, and distribution are studied within the
context of the cell, the organism (e.g. dominance), and within the
context of a population. Genetics has given rise to a number of subfields, including molecular
genetics, epigenetic and population genetics. Organisms
studied within the broad field span the domains of life
(Archaea, Bacteria, and Eukarya).
Genetic processes work in
combination with an organism's environment and experiences to influence
development and behavior, often referred to as nature versus nurture.
The intracellular or extracellular environment of a living
cell or organism may switch gene transcription on or off. A classic example is
two seeds of genetically identical corn, one placed in a temperate climate and
one in an arid climate (lacking sufficient waterfall or rain). While the
average height of the two corn stalks may be genetically determined to be
equal, the one in the arid climate only grows to half the height of
the one in the temperate climate due to lack of water and nutrients in its
environment.
Since the dawn of
civilization, humankind has recognized the influence of heredity and applied
its principles to the improvement of cultivated crops and domestic
animals. A Babylonian tablet more than 6,000 years old, for example,
shows pedigrees of horses and indicates possible inherited
characteristics. Other old carvings show cross-pollination of date
palm trees. Most of the mechanisms of heredity, however, remained a
mystery until the 19th century, when genetics as a
systematic science began.
Definition of Genetic
Genetics may be defined as the
study of genes at all levels, including the ways in which
they act in the cell and the ways in which they are
transmitted from parents to offspring. Modern genetics focuses on the chemical
substance that genes are made of, called deoxyribonucleic acid, or DNA,
and the ways in which it affects the chemical reactions
that constitute the living processes within the cell.
Genetics action depends on
interaction with the environment. Genetics arose out of the identification
of genes, the fundamental units responsible for heredity. Green plants, for example, have genes containing the
information necessary to synthesize the photosynthetic pigment chlorophyll that gives them their green
colour. Chlorophyll is synthesized in an environment containing light because
the gene for chlorophyll is expressed only when it interacts with light. If a
plant is placed in a dark environment, chlorophyll synthesis stops because the
gene is no longer expressed.
Examples of Genetics
1. Classical or formal genetics:
The study of the transmission of single genes within families and the analysis
of more complex types of inheritance.
2. Clinical genetics:
The diagnosis, prognosis and, in some cases, the treatment of genetic diseases.
3. Genetic counseling: An
important area within clinical genetics involving the diagnosis, risk assessment,
and interpersonal communication.
4.
Cancer genetics: The study of genetic factors
in inherited and sporadic cancer.
5. Cytogenetic:
The study of chromosomes in health and disease.
6. Biochemical genetic:
The biochemistry of nucleic acids and proteins including enzymes.
7.
Pharmacogenetics: How genes govern the absorption, metabolism
and disposal of drugs and untoward reactions to them.
8. Molecular genetics: The
molecular study of genetics including particularly DNA and RNA.
9.
Immunogenetics: The genetics of the immune system including
blood groups, HLA, and the immunoglobulin.
10. Behavioral genetics:
The study of genetic factors in behavior in health and disease including mental
retardation and mental illness.
11. Population genetics:
The study of genes within populations including gene frequencies, the gene
pool, and evolution.
12. Reproductive genetics:
The genetics of reproduction including genes and chromosomes in germ cells and
the early embryo.
13. Developmental genetics:
The genetics of normal and abnormal development including congenital malformations (birth
defects).
14. Cancer genetics: The
study of the genetic factors in inherited and sporadic cancer.
15.
Eco-genetics: The interaction of genetics with the
environment.
16. Forensic genetics:
The application of genetic knowledge, including DNA, to legal matters.
Read On: What is genetics and its importance
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