2.9 - Chromosomal Theory of Inheritance

6. Walter Sutton and Theodore Boveri noted that the behaviour of chromosomes was parallel to the behaviour of genes and used .............. (Figure 2.8) to explain Mendel’s laws.
7. Finally, though Mendel’s work suggested that .......... (genes) were discrete units, he could not provide any physical proof for the existence of factors or say what they were made of.
8. Firstly, .......... was not easy (as it is now) in those days and his work could not be widely publicised.
10. The important things to remember are that chromosomes as well as genes occur in .........
13. Thirdly, Mendel’s approach of using ........... to explain biological phenomena was totally new and unacceptable to many of the biologists of his time.
15. By 1902, the chromosome movement during ......... had been worked out.
16. In the left column (Possibility I) orange and .......... is segregating together.
17. The two alleles of a gene pair are located on .......... sites on homologous chromosomes.
19. In 1900, three Scientists (de Vries, Correns and von Tschermak) independently ............ Mendel’s results on the inheritance of characters.
21. .......... and ......... argued that the pairing and separation of a pair of chromosomes would lead to the segregation of a pair of factors they carried.

1. Sutton united the knowledge of chromosomal segregation with Mendelian principles and called it the ........... of inheritance.
2. Also, by this time due to advancements in microscopy that were taking place, scientists were able to carefully observe ..........
3. To understand this, compare the chromosomes of ........... colour in the left and right columns.
4. of the pair of alleles which did not ‘blend’ with each other, was not accepted by his ............... as an explanation for the apparently continuous variation seen in nature.
5. Mendel published his work on inheritance of characters in 1865 but for several reasons, it remained ........... till 1900.
9. But in the right hand column (Possibility II) the orange chromosome is segregating with the ............
11. Secondly, his concept of genes (or factors, in Mendel’s words) as .......... and ......... units that controlled the expression of traits.
12. This led to the discovery of structures in the .......... that appeared to double and divide just before each cell division.
14. Recall that you have studied the behaviour of chromosomes during .......... (equational division) and during meiosis (reduction division).
18. During Anaphase of meiosis I, the two chromosome pairs can align at the ........... plate independently of each other
20. These were called ........... (colored bodies, as they were visualised by staining).