.::. ÖGGGT .::. Austrian Association for Genetics and Genetic Engineering .::.

ÖGGGT Genetics

Genetics (from the Greek genno γεννω = give birth) is the science of genes, heredity, and the variation of organisms. The word "genetics" was first suggested to describe the study of inheritance and the science of variation by the prominent British scientist William Bateson in a personal letter to Adam Sedgwick, dated April 18, 1905. Bateson first used the term "genetics" publicly at the Third International Conference on Genetics (London, England) in 1906.

Heredity and variations form the basis of genetics. Humans applied knowledge of genetics in prehistory with the domestication and breeding of plants and animals. In modern research, genetics provides important tools for the investigation of the function of a particular gene, e.g., analysis of genetic interactions. Within organisms, genetic information generally is carried in chromosomes, where it is represented in the chemical structure of particular DNA (deoxyribonucleic acid) molecules.

source:http://www.biologie.hu-berlin.de/~zoologie/sammlung/Tafeln/Genetik.html

Genes encode the information necessary for synthesizing the amino-acid sequences in proteins, which in turn play a large role in determining the final phenotype, or physical appearance, of the organism. In diploid organisms, a dominant allele on one chromosome will mask the expression of a recessive gene on the other.

The phrase to code for is often used to mean a gene contains the instructions about how to build a particular protein, as in the gene codes for the protein. The "one gene, one protein" concept is now known to be simplistic. For example, a single gene may produce multiple products, depending on how its transcription is regulated. Genes code for the nucleotide sequences in mRNA, tRNA and rRNA, required for protein synthesis.

Genetics determines much (but not all) of the appearance of organisms, including humans, and possibly how they act. Environmental differences and random factors also play a part. Monozygotic ("identical") twins, a clone resulting from the early splitting of an embryo, have the same DNA, but different personalities and fingerprints. Genenetically-identical plants grown in colder climates incorporate shorter and less-saturated fatty acids to avoid stiffness.

History of Genetics

In his paper "Versuche über Pflanzenhybriden" ("Experiments in Plant Hybridization"), presented in 1865 to the Brunn Natural History Society, Gregor Mendel traced the inheritance patterns of certain traits in pea plants and showed that they could be described mathematically. Although not all features show these patterns of Mendelian inheritance, his work suggested the utility of the application of statistics to the study of inheritance. Since that time many more complex forms of inheritance have been demonstrated.

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 did not understand the nature of inheritance. We now know that some heritable information is carried in DNA. (Retroviruses, including influenza, oncoviruses and HIV, and many plant viruses, carry information as RNA.) Manipulation of DNA can in turn alter the inheritance and features of various organisms.

Timeline of notable discoveries

1859 Charles Darwin publishes The Origin of Species
1865 Gregor Mendel's paper, Experiments on Plant Hybridization
1869 Friedrich Miescher discovers a weak acid in the nuclei of white blood cells that today we call DNA (Hartl and Jones).
1880-1890 Walther Flemming, Eduard Strasburger, and Edouard van Beneden elucidate chromosome distribution during cell division
1903 Chromosomes are discovered to be hereditary units
1906 The term "genetics" is first introduced publicly by the British biologist William Bateson at the Third International Conference on Genetics in London, England.
1910 Thomas Hunt Morgan shows that genes reside on chromosomes, and discovered linked genes on chromosomes that do not follow Mendel's law of independent allele segregation
1913 Alfred Sturtevant makes the first genetic map of a chromosome
1913 Gene maps show chromosomes containing linear arranged genes
1918 Ronald Fisher publishes On the correlation between relatives on the supposition of Mendelian inheritance - the modern synthesis starts.
1927 Physical changes in genes are called mutations
1928 Frederick Griffith discovers a hereditary molecule that is transmissible between bacteria (see Griffiths experiment)
1931 Crossing over is the cause of recombination (see Barbara McClintock and cytogenetics)
1941 Edward Lawrie Tatum and George Wells Beadle show that genes code for proteins; see the original central dogma of genetics
1944 Oswald Theodore Avery, Colin McLeod and Maclyn McCarty isolate DNA as the genetic material (at that time called transforming principle)
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., the nucleotide bases Adenine-Thymine and Cytosine-Guanine always remain in equal proportions). Barbara McClintock discovers transposons in maize
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 D. Watson and Francis Crick, with the help of Rosalind Franklin
1956 Jo Hin Tjio and Albert Levan established the correct chromosome number in humans to be 46
1958 The Meselson-Stahl experiment demonstrates that DNA is semiconservatively replicated
1961 The genetic code is arranged in triplets
1964 Howard Temin showed using RNA viruses that Watson's central dogma is not always true
1970 Restriction enzymes were discovered in studies of a bacterium, Haemophilus influenzae, enabling scientists to cut and paste DNA
1972, Walter Fiers and his team at the Laboratory of Molecular Biology of the University of Ghent (Ghent, Belgium) were the first to determine the sequence of a gene: the gene for Bacteriophage MS2 coat protein.
1976, Walter Fiers and his team determine the complete nucleotide-sequence of Bacteriophage MS2-RNA
1977 DNA is sequenced for the first time by Fred Sanger, Walter Gilbert, and Allan Maxam working independently. Sanger's lab complete the entire genome of sequence of Bacteriophage Φ-X174
1983 Kary Banks Mullis discovers the polymerase chain reaction enabling the easy amplification of DNA
1985 Alec Jeffreys discovers genetic finger printing.
1989 The first human gene is sequenced by Francis Collins and Lap-Chee Tsui. It encodes the CFTR protein. Defects in this gene cause cystic fibrosis
1995 The genome of Haemophilus influenzae is the first genome of a free living organism to be sequenced.
1996 Saccharomyces cerevisiae is the first eukaryote genome sequence to be released
1998 The first genome sequence for a multicellular eukaryote, C. elegans is released.

.::. ÖGGGT .::. Austrian Association for Genetics and Genetic Engineering .::.