Every living cell has a centrally placed circular and dusky structure called “nucleus“.
The nucleus function is key to a cell’s normal survival and multiplication.
The cells with a well-formed nucleus are called eukaryotic cells.
The cells lacking this clearly defined nucleus are called prokaryotic cells like bacteria.
The nucleus appears as a spherical body when viewed under a microscope. It is the largest organelle of the cell visible under the microscope.
It is spherical in appearance in most cases while it can also have other shapes i.e polymorphic. It looks dense and thick under a microscope.
There is a double membrane nuclear membrane encircling such that it encloses entire nuclear contents.
1. As shown in the picture, there is an outer nuclear membrane (ONM) and inner nuclear membrane (INM).
2. It also has nucleoplasm (i.e fluid matrix of the nucleus), DNA, chromosomes, nucleolus. On the membrane, there are few nuclear pores for connection with the external cytoplasm.
3. On its surface, endoplasmic reticulum bodies are attached but they do not belong to the nucleus.
Cell Nucleus function & importance:
♣ The pores on the nucleus help in the transfer of formed messenger ribonucleic acids (mRNA) from the nucleus into the cytoplasm. These mRNA’s sit on the surface of the endoplasmic reticulum to guide the formation of proteins. The amino-acids and other substances required for DNA, RNA, etc. formation move from the cytoplasm into the nucleus.
♣ Nuclear receptors are those receptors present in the nucleus. Steroid and other drugs act by regulating the genes in the nucleus by fixing onto the receptors on the nuclear membrane.
♣ Cell division is an important nucleus function. It initiates the process by DNA replication, then nucleus, and also cell membrane divisions. It is involved in both mitotic and meiotic cell divisions.
♣ The genes determine the characteristics of the cell’s proteins, including the structural proteins, as well as the intracellular enzymes that control cytoplasmic and nuclear activities.
♣ The genes also control and promote the 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.