Genetics
This article deals with genetics as a branch of biology. For genetics in linguistics, see Genetic relationship (linguistics).
Genetics (modern neologism of the ancient Greek γενεά geneá "descent" and γένεσις génesis, German 'Ursprung') or heredity (formerly also hereditary biology) is the science of heredity and a branch of biology. It deals with the laws and material foundations of the formation of hereditary characteristics and the transmission of hereditary dispositions (genes) to the next generation.
The knowledge that individual traits are passed on over several generations is relatively recent; ideas of such natural inheritance processes only began to take shape in the 18th and early 19th centuries. The founder of genetics in this sense is considered to be the Augustinian monk Gregor Mendel, who systematically carried out crossing experiments with peas in the garden of his monastery between 1856 and 1865 and evaluated them statistically. In this way he discovered Mendel's rules, which were later named after him, but which were not received and confirmed in science until 1900. By far the most important branch of genetics today is molecular genetics, which deals with the molecular basis of heredity. It gave rise to genetic engineering, in which the findings of molecular genetics are applied in practice.
Recombination of parental genes results in different phenotypes within a litter.
Etymology
The adjective "genetic" was already used around 1800 by Johann Wolfgang von Goethe in his work on the morphology of plants and subsequently frequently in Romantic natural philosophy as well as in descriptive embryology. Unlike today, it meant a method ("genetic method") of studying and describing the individual development (ontogenesis) of organisms. The noun "genetics" was first used by William Bateson in 1905 to describe the new research discipline.
In Germany, the term "hereditary biology" was used synonymously until the second half of the 20th century, mostly to distinguish "human hereditary biology" (human genetics) from general genetics. The term "human genetics" was already established in Germany around 1940. This indicated a retreat to scientifically required basic research, while "racial hygiene" represented applied science. After 1945, the terms "hereditary biology" and "racial hygiene" gradually disappeared from scientific usage.
Subsections
- Classical genetics, founded by Mendel, investigates the combinations in which genes appear in the offspring in crossbreeding experiments (Mendelian rules) and how this influences the expression of certain phenotypic characteristics. Classical genetics also includes cytogenetics, which examines the number, shape and structure of chromosomes as carriers of genetic information in the light microscopic size range.
- Molecular genetics - a branch of molecular biology - investigates the molecular basis of heredity: the structure of the molecular carriers of hereditary information (usually DNA, in the case of some viruses RNA), the duplication of these macromolecules (replication) and the resulting changes in the information content (mutations, recombination) as well as the realisation of the hereditary information in the course of gene expression (transcription and translation). Molecular genetics also includes genetic engineering as an applied field.
- Population genetics and ecological genetics study genetic structures and processes at the level of populations and other ecological units (e.g. entire communities).
- Epigenetics deals with the transmission of traits to offspring that are not due to deviations in the DNA sequence, but to heritable changes in gene regulation.
Transmission of phenotypic traits: Father and son with hairy vertebrae and otapostasis
Questions and Answers
Q: What is genetics?
A: Genetics is a discipline of biology that studies the inheritance of variation and traits of living organisms, as well as how parents pass some characteristics to their children.
Q: What did people know about heredity in prehistoric times?
A: People in prehistoric times knew that living things inherit traits from their parents and used this knowledge to improve crop plants and animals through selective breeding.
Q: Who was Gregor Mendel?
A: Gregor Mendel was a scientist in the mid-nineteenth century who studied the process of inheritance. He observed that organisms inherit traits via discrete units of inheritance, now called genes.
Q: How does modern genetics differ from what was known in prehistoric times?
A: Modern genetics has expanded beyond just understanding inheritance; it also studies the way genes work.
Q: What are genes?
A: Genes are discrete units of inheritance which determine certain characteristics or traits passed down from parent to offspring.
Q: How do scientists study genetics in the laboratory?
A: Scientists study genetics by mating carefully selected organisms and analysing their offspring.
Q: Why is genetics important for evolution?
A: Genetics gives us basic rules on which evolution acts, so it is an important part of biology for understanding how species change over time.
