4.6.3.3 the understanding of genetics

• Who was Mendel?

  An Austrian monk
• what did he do?

  He did experiments with pea plants to demonstrate how characteristics are inherited
• what did Mendel’s experiments show?

  which characteristics were dominant or recessive in the same pea plants
• what were the three important conclusions Mendel reached?

  1. Characteristics in plants are determined by ‘hereditary units’
  2. Hereditary units are passed on to offspring from both parents, one unit from each parent
  3. Hereditary units can be dominant or recessive - if an individual has both the dominant and recessive unit for a characteristic, the dominant characteristic will be expressed
• when did Mendel carry out his experiments?

  mid-19th century
• what was discovered in the late 19th century?

  behaviour of chromosomes during cell division
• what has discovered in the early 20th century?

  chromosomes and Mendel’s ‘units’ behaved in similar ways - this led to the idea that the ‘units’, now called genes, were located on chromosomes
• what was discovered in the mid-20th century?

  the structure of DNA and the mechanism of gene function