The Work of Mendel
- Gregor Mendel was an Austrian monk
- He was studied mathematics and natural history at the University of Vienna
- In the mid-19th century, Mendel carried out breeding experiments on plants
- He studied how characteristics were passed on between generations of plants
- For example, he conducted studies with pea plants and looked at how the height characteristic was inherited
- In the first experiment, he crossed a tall pea plant with a dwarf pea plant
- In the second experiment, he crossed two of the tall offspring together
The pea plant crosses were originally carried out by Mendel to investigate the inheritance of characteristics
- One of his observations was that the inheritance of each characteristic is determined by ‘units’ that are passed on to descendants unchanged
- Using the example above, Mendel showed that height in pea plants was the result of separately inherited ‘hereditary units’ passed down from each parent plant to the offspring plants – this particular experiment showed that the ‘unit’ for tall plants (T) was dominant over the ‘unit’ for short plants (t)
- He also carried out experiments to show how other characteristics of pea plants are inherited in the same way
- E.g. Flower colour
Mendel's conclusions
- Three important conclusions about hereditary in plants were reached
- Characteristics are determined by 'hereditary units' and these hereditary units are passed on from parent to offspring unchanged
- The offspring receives one 'hereditary unit' from each parent
- Hereditary units can be dominant or recessive (a dominant characteristic is always expressed when present)
Understanding Mendel's work
- His work eventually provided the foundation for modern genetics
- The importance of Mendel’s discovery was not recognised until after his death:
- His studies were totally new to science in the 19th century
- There was no knowledge of the mechanisms behind his findings (DNA, genes and chromosomes had not been discovered yet)
