4.6.3.3 The understanding of genetics

Question 1

Describe the development of our understanding of genetics including the work of Mendel.

Answer 1

• By experimenting with pea plant breeding, Mendel developed three principles of inheritance that described the transmission of genetic traits, before anyone knew genes existed.
• Law of Dominance, Law of Segregation, Law of Independent Assortment

Question 2

Why was the importance of Mendel’s discovery not recognised until after his death?

Answer 2

• Everything was happening in the eighteen hundreds and scientists didn’t know anything about DNA or genes

Question 3

What happened in the mid 19th century?

Answer 3

• In the mid 19th century Greg Mendel carried out breathing experiments on plants
• One of his observations was that the inheritance of each characteristic is determined by “hereditary units” (recessive or dominant) that are passed on to descendants unchanged

Question 4

What happened in the late 19th century?

Answer 4

• Behaviour of chromosomes during cell division was absurd

Question 5

What happened in the early 20th century?

Answer 5

• In the early 20th century it was observed that chromosomes and Mendel’s units behaved in similar ways
• This led to the idea that the units and I call genes were located on chromosomes

Question 6

What happened in the mid twentieth century?

Answer 6

• The structure of DNA was determined and the mechanism of gene function worked out

Question 7

How was the gene theory developed?

Answer 7

• This scientific work by many scientists led to the gene theory being developed