The science of genetics deals with genes and
biological inheritance, by which a predisposition to parental
traits is passed to offspring at conception. Humans began applying
knowledge of genetics in prehistory with the domestication and
breeding of plants and animals. Within organisms, genetic information
generally is carried in chromosomes, where it is represented
in the chemical structure of particular DNA molecules.
The science which grew out of the union of
biochemistry and genetics is widely known as molecular biology.
The term "genetics" is often widely conflated with
the notion of genetic engineering, where the DNA of an organism
is modified for some kind of practical end, but most research
in genetics is aimed at understanding and explaining the effect
of genes on phenotypes and in the role of genes in populations
(see population genetics), rather than genetic engineering.
A more recent development is the rise of genomics, which attempts
the study of large-scale genetic patterns across the genome
for (and in principle, all the DNA in) a given species.
The study of inherited features not strictly
associated with changes in the DNA sequence is called epigenetics.
Some take the view that life can be defined,
in molecular terms, as the set of strategies which RNA polynucleotides
have used and continue to use to perpetuate themselves. This
definition grows out of work on the origin of life, specifically
the RNA world hypothesis.
It wasn't until 1865 that Gregor Mendel first
traced inheritance patterns of certain traits in pea plants
and showed that they obeyed simple statistical rules. Although
not all features show this Mendelian inheritance, his work acted
as a proof that application of statistics to inheritance could
be highly useful. Since that time many more complex forms of
inheritance have been demonstrated.
From his statistical analysis Mendel defined
a concept that he described as an allele, which was the fundamental
unit of heredity. The term allele as Mendel used it is nearly
synonymous with the term gene, whilst the term allele now means
a specific variant of a particular gene.
The significance of Mendel's work was not
understood until early in the twentieth century, after his death,
when his research was re-discovered by other scientists working
on similar problems.
Mendel was unaware of the physical nature
of the gene. We now know that genetic information is normally
carried on DNA. (Certain viruses store their genetic information
in RNA). Manipulation of DNA can in turn alter the inheritance
and features of various organisms.
Genes encode the information necessary for
synthesizing proteins, which, in turn play a large role in influencing,
although do not completely determine, the final phenotype of
Timeline of Notable Discoveries in Genetics
1859 Charles Darwin publishes The Origin of
1865 Gregor Mendel's paper, Experiments on Plant Hybridization
1903 Chromosomes are discovered to be hereditary units
1905 British biologist William Bateson coins the term "genetics"
in a letter to Adam Sedgwick
1910 Chromosomes include genes
1913 Gene maps show chromosomes containing linear arranged genes
1927 Physical changes in genes are called mutations
1928 Frederick Griffith discoveres a hereditary molecule that
is transmissible between bacteria (see Griffiths experiment)
1931 Crossing over is the cause of recombination
1944 Oswald Theodore Avery, Colin McLeod and Maclyn McCarty
isolate DNA as the genetic material (at that time called transforming
1945 Genes code for proteins; see the original central dogma
1950 Erwin Chargaff shows that the four nucleotides are not
present in nucleic acids in stable proportions, but that some
general rules appear to hold (e.g., that the amount of adenine,
A, tends to be equal to that of thymine, T).
1952 The Hershey-Chase experiment proves the genetic information
of phages (and all other organisms) to be DNA
1953 DNA structure is resolved to be a double helix by James
Watson and Francis Crick
1958 The Meselson-Stahl experiment demonstrates that DNA is
1961 The genetic code is arranged in triplets
1977 DNA is sequenced
1997 First genome sequenced
2001 First draft sequences of the human genome are released
simultaneously by the Human
Genome Project and Celera Genomics.
2003 (14 April) Successful completion of Human Genome Project
with 99% of the genome sequenced to a 99.99% accuracy
Site of the U.S. Human Genome Project, Genomics:GTL Program,
and Microbial Genome Program--all sponsored by the U.S. Department
of Energy Genome Programs.
Genome Project Information
The main homepage for Human Genome Project information --what
the project is; its progress, history, and goals; what issues
are associated with genome research; frequently asked questions,
the science behind the project; who its sponsors are..
American Journal of Human Genetics
Since its inception in 1948, AJHG has provided
a record of research and review relating to heredity and human
Promotes research in basic and applied human and
Genetics Society of Australasia
Promote standards, research, and education.
International Federation of Human Genetics Societies
Provides a forum for organized groups including
research, clinical practice, and professional.
HGU - Medical Research Council Human Genetics Unit
Undertakes research to obtain a molecular and
cellular understanding of genetic factors.
Institute of Human Genetics
Features graduate program and current faculty
research interests in areas of human genetics.
- International Communication Forum in Human Molecular ...
Features a mailing list, table of contents of
leading journals, listings of meetings and seminars.