Whether the child will be a son or daughter

Now we can understand easily that the father or mother is responsible for the birth of a son or daughter. Both male and female have 44 autosomes, a pair of sex chromosome. Sex chromosome of a female is XX and that of the male is XY. The male gamete (sperm) bears X and Y chromosome. But the female gamete (egg) bears X and X. If the X bearing egg of the female is united (fertilize) with Y bearing sperm of the male, the child will have XY. A child having such chromosomes will be a male child. It is seen that if there is no Y chromosome, the child will never be a son. There is no Y chromosome in a female; Y chromosome is present only in male. So if a couple do not have any male child, the husband is responsible not the wife.

A figure on this ssue shows:

 

Read more »

Male-Female determining Chromosome

Every living being has a definite number of chromosomes. In human beings there are 23 pairs of chromosome. Among them 22. pairs are similar in both male and female, these are Autosomes . Members of the remaining pair of chromosome are different in male and female. This pair of chromosome determines the sex of human beings. As they determine the sex, so they are called X and y sex chromosome or sex determining chromosome. One of the sex chromosomes is X chromosome and the other is Y chromosome. If the sex chromosome pair is XY, the child will be male (son), and if it is XX, the child will be female (daughter). In Drosophylla (a fly) also XX indicate female and XY male. So in case of determining the sex, the role of  X and Y chromosome is vital.

Read more »

Different Stages of Mitosis

Mitosis is a continuous process. The process is completed by a complex  method. According to the sequence and stages, this continuous process is divided into five stages. The stages are:

(1)Prophase,

(2) Pro-Metaphase,

(3) Metaphase,

(4) Anaphaseand

(5) Telophase.

               Ø  Prophase: At this stage, the nucleus swells up.Chromosomes begin to be dehydrated. As a result, the chromosomes gradually become shorter and thicker. Then they are visible under microscopes. At the end of this stage nucleolus and nuclear membrane become disappear.

 

 

 Ø  Pro-Metaphase : At the beginning of this stage. the fibrous protein converse toform a bi-polar spindle apparatus. Each chromosome is then become attached to a fibre of the spindle apparatus by its centromere. Each fibre of the spindle apparatus is called spindle fibre. The fibre to which the chromosomes are attached is called traction fibre. As they are attached with the chromosomes so they also called hromosomal fibre. In animal cell aster rays re radiated from centrioles present at two poles.

   

  
Ø  Metaphase: Chromosomes are arranged at the equatorial plane of the spindle. The

centromere of each chromosome remains at the equatorial plane and the two arms are placed towards two poles. At this stage, the chromosomes become maximum thick and short. Two chromatids of a chromosome become maximum thick and short. Two chromatids of a chromosome become clearly visible and the centromere is divided in to two parts.

    

    
  Ø  Anaphase: Two separate chromatids of a chromosome move towards the opposite pole of the spindle apparatus. Centromere goes ahead at the movement of the chromatids towards the pole and the arms follow them. when the daughter chromosomes reaches near the poles the anaphase stage ends.

   

 Ø  Telophase: Daughter chromosomes take position at two opposite poles.Chromosomes gradually take water and become elongated, thin and long. Nuclear membrane develops encircling the chromosomes. Nucleolus reappears at the secondary constriction of the Sat chromosome. Spindle apparatus disappears. At the end of this stage, gradually a cell wall develops at the equatorial region of the cell. As a result, the mother cell divides into two daughter cells. In case of animal cells, instead of formation of cell wall the cell membrane is constricted inwardly and the cell divides into two.

Read more »