Mendel

• Mendel believed that ‘units’ were transferred from one organism to another. These units led to the transfer of characteristics.
• Mendel looked at the difference between smooth and wrinkled peas to work out which were dominant and recessive characteristics. This led to the understand that smooth peas were a dominant characteristics, whereas wrinkled peas were a recessive characteristic.
• Mendel's work was too advanced for his time and went against popular heredity beliefs
• Mendel's work was during the mid 19th century
• In the late 1800s, scientists were able to observe how chromosomes behaved during cell division. Then, in the early 20th century scientists realised there were striking similarities in the way that chromosomes in Mendel's hereditary units acted. Based on this, it was proposed that the units found on chromosomes were now called genes. In the mid-20th century, the structure of DNA was determined, allowing scientists to determine how genes work
• Penicillin was discovered by Alexander Fleming