In this article we will discuss about:- 1. Distribution and Occurrence of Polyploidy 2. Classification of Polyploidy. Distribution and Occurrence of Polyploidy: Polyploidy is wide spread in plant kingdom but is less common in animal kingdom. Darlington and Janaki-Ammal in 1945 and Stebbins in 950 estimated that polyploids make up 30 to 35% of Angiosperms. In certain families, very high [...]
In this article we will discuss about:- 1. Classification of Haploids 2. Origin of Haploids 3. Meiosis. Classification of Haploids: According to their cytological features, haploids have been classified into different types (Fig. 17.1), a brief description of which is given below. I. Euhaploid: The chromosome number of such a haploid is an exact multiple of one of the basic [...]
The following points highlight the five main types of trisomics which is a cell tissue or individual possessing the extra chromosome. The types are: 1. Primary Trisomics 2. Secondary Trisomics 3. Telocentric or Telosomic or Telotrisomics 4. Tertiary Trisomics 5. Compensating Trisomics. Type # 1. Primary Trisomic: In this type of trisomic, the extra chromosome is normal and completely homologous [...]