Victoria Booth
Nucleus
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Answer
Describe the main functions of the nucleus (cell organelle)
12th May 2025
The cell nucleus plays a significant role in controlling metabolic activities within the cell, in cell division, and many other cellular processes. The great majority of a cell’s genetic information is contained within its chromosomes which are located within the nucleus. (The mitochondria in the cytoplasm also contain some DNA for their own use.) At the molecular level, the chromosomes are made up of long molecules of deoxyribonucleic acid (DNA) wrapped around special proteins known as histones. DNA carries the hereditary information as a series of factors or genes along its length. The chromosomes are copied exactly before a cell divides and a complete set of genetic information is passed to each new daughter cell.
This process is called mitosis and is necessary for the growth and development of all living organisms.
The genes specify the structure of the many proteins required by living systems. In turn, the proteins determine the characteristics and behaviour of cells – their day-to-day activities and the longer-term pattern of development of the organism. Information carried by genes is written in the sequence of the 4 nucleotide building blocks of the DNA molecules. Since genes remain within the nucleus, whilst most of the processes they control take place in the cytoplasm of the cell, a mechanism is required to convey the information out of the nucleus. This mechanism is called transcription, and the nucleotide sequence in DNA is copied onto a corresponding nucleotide sequence in RNA (ribonucleic acid). This messenger RNA’ is transported out of the nucleus to the sites of protein synthesis (ribosomes) in the cytoplasm.
In addition to chromosomes, the nucleus contains one or more spherical objects called nucleoli. These structures contain RNA along with some DNA and proteins. Their main function is in the manufacture of ribosomes. Each nucleolus produces the subunits needed to make ribosomes and these are passed to the cytoplasm for final assembly.
