Chromatin is a complex of DNA and proteins, which is intensively stained with some dyes and differs in shape from the nucleolus. In dividing cells, DNA molecules are strongly spiralized, shortened and become compact in size and shape. This compact state of DNA is called chromosomes.
Chromosomes are organelles of the cell nucleus, the combination of which determines the basic hereditary properties of cells and organisms. A complete set of chromosomes in a cell characteristic of a given organism is called a karyotype. In any cell of the body of most animals and plants, each chromosome is represented twice: one of them is received from the father, the other from the mother during the fusion of the nuclei of germ cells during fertilization. Such chromosomes are called homologous, a set of homologous chromosomes – diploid.
The shape of the chromosomes depends on the position of the so-called primary constriction, or centromere, the region to which the threads of the division spindle are attached during cell division (mitosis). The centromere divides the chromosome into two shoulders, which can be the same or different lengths.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.