NUCLEUS & Nucleoli and Formation of Ribosomes

Nucleus

: The nucleus is the control center of the cell. Briefly, the nucleus contains large quantities of DNA, which are the genes. The genes determine the characteristics of the cell’s proteins, including the structural

                     

Proteins and  the intracellular enzymes that control cytoplasmic and nuclear activities. The genes also control and promote reproduction  of the cell itself. The genes first reproduce to give two identical sets of genes; then the cell splits by a special process called mitosis to form two daughter cells, each  of which receives one of the two sets of DNA genes.

Nucleoli and Formation of Ribosomes

The nuclei of most cells contain one or more highly  staining structures called nucleoli. The nucleolus does not have a limiting membrane. Instead, it is simply an accumulation  of large amounts of RNA and proteins of the types found in ribosomes. The nucleolus becomes considerably enlarged when the cell is actively synthesizing  proteins. Formation of the nucleoli (and of the  ribosomes  in  the cytoplasm outside the nucleus) begins in the nucleus.