Short Notes on Anaeoploidy, Euploidy and Vacuole


ANAEOPLOIDY
It is change in number of chromosome which can be either due to loss of one or more chromosomes or due to addition or deletion of one or more chromosomes. It leads to variations in chromosome number and do not involve the whole of the Karyothype. The nuclei of the aneuploids contain chromosomes whose number is not true mullyple of the basic number (n). The aneuploidy arises due to non disjunction. The loss of one chromosome produces a Monosomic (2n—1) and the condition is termed as Monosomy. The gain of one chromosome produces Trisomic (2n—1) and the condition is known as Trisomy. In the same way the addition of two or more chromosomes is respectively known as Tetrasomy and Pentasomy, the individuals are known as Tetrasomic and Pentasomic. In some cases a pair of homologous chromosomes is lost (2n—2), such indivividuals are termed as Nullisomic and the condition is called Nullisomy.

EUPLOIDY:
It is a condition where one or more full sets of chromosomes are present in an organism. The euploids may e Monoploids, Diploids or Polyploids. Monoploids can be distinguished from haploids as they have a single basic set of chromosomes are in Barley 2n = x = 7 or in corn 2n = x = 10 while the Haploids have the half the somatic number of chromosomes found in normal individual i.e. each chromosome is represented once. In some cases as in male insects the haploids are produced due to parthenogenesis. In these insects the queen and drones are diploid females. The haploids also originate due to development of egg parthenogenetically in following plants such as Tomatoes and Cotton. The haploids also originate from pollen tube rather than from egg, synergids or antipodals of the embryo sac. Such haploids are known as Androgenic Haploids.

Significance: Haploids are characterised by a reduction in size of all vegetative and floral parts than a diploid. Haploids are used in production of homozygous diploids as haploids can be doubled by colchicines treatment. These homologous diploids are used for cultivation e.g. rice, wheat and tobacco.

VACUOLE:
Vacuoles are non protoplasmic liquid filled cavities in the cytoplasm and are surrounded by a membrane called the tonoplast. Tonoplast is selectively permeable; it allows certain substancesto enter in the vacuole. They are clear in plant cells. They are prominent in nature cells. They are filled with cell sap and act as store house, which often plays role in plant defence,

Which is necessary for plant cell enlargement. Plant vacuoles sometimes act as lysosome as they contain hydrolytic enzymes and after death of cells tonoplast lose its differential permeability and its enzyme causes lysis of the cell. Vacuole is filled with a fluid called cell sap which is water containing large number of soluble chemical substances such as inorganic salts, organic acids, soluble carbohydrates e.g. sugar, soluble proteins, and amino acids and in certain cells mucilage, anthocyamins, tannins, latex and alkaloids in varying proportions. The vacuole is this a tiny reservoir of the cell from which the cytoplasm draws water and other material according to its need.

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