THE MOST IMPORTANT ORGANELLE - THE NUCLEOLUS

THE NUCLEOLUS: THE BRAINS OF THE NUCLEUS

THE NUCLEOLUS: WHERE IS IT?

The nucleolus is located within the nucleus of an eukaryotic cell. The nucleolus lacks its own membrane and simply sits inside the nucleus.

Figure 1: The above image displays the nucleus of a cell. The nucleolus is labelled as the purple centre.

THE NUCLEOLUS: HOW IT FUNCTIONS:

The nucleolus produces the components for ribosomes, which then move out of the nucleus to produce proteins. In the most prominent substructure within the nucleus, the nucleolus is where the site of rRNA transcription and processing, and of ribosome assembly take place. rRNA is short for ribosomal ribonucleic acid. These are essential for protein synthesis in all living organisms. It constitutes the predominant material within the ribosome, which is approximately 60% rRNA and 40% protein by weight.

Figure 2: The above video explains the functions of the organelles found in a plant cell. The nucleus and nucleolus is described near 2:20.

THE NUCLEOLUS: WHY IS IT IMPORTANT?

As mentioned above, the nucleolus plays a vital role in building ribosomes and rRNA. Ribosomes are the protein builders or the protein synthesizers of the cell. Without the nucleolus, the cell would not be able to create ribosomes, therefore unable to creating proteins. Without the nucleolus, the cell WOULD NOT BE ABLE TO FUNCTION!

Figure 3: The above image clearly displays the nucleolus in the centre of the nucleus in a cell. 

THE NUCLEOLUS: COMPARED TO A CITY

The cell is often compared to a city, where the golgi bodies are post offices or UPS trucks, endoplasmic reticulum are the highways and roads, ribosomes are the factories and construction sites. The nucleus controls the cell activities and contains the nucleolus and the DNA which dictates cell activities and provides regulations to the cell. This is functionally equivalent to the City Hall which is responsible for execution of the law. The nucleolus however, controls the executive activity within the nucleus of the cell and contains the chromosomes and the DNA of the cell. This can be compared to the mayor of the city who controls and has the power to veto the rest of the politicians and executives in the City Hall.



Figure 4: The above image illustrates the "cell city." The nucleolus would be found in the municipal government.

THE NUCLEOLUS: A SUMMARY 

• The nucleolus is not surrounded by a membrane.
• The nucleolus is the nuclear subdomain that assembles ribosomal subunits in eukaryotic cells.
• The nucleolus is the site of rRNA transcription and processing, and of ribosome assembly.
• The nucleolus, whose primary function is to assemble ribosomes, is the largest structure in the cell nucleus.
• The nucleolus disassembles at the beginning of mitosis and begins to reassemble in telophase.

Figure 5: The above image is of the nucleolus in the nucleus.

WITHOUT THE NUCLEOLUS, THERE WOULD BE NO CELL, THEREFORE NO LIFE! IT'S LIKE A BODY WITH NO BRAIN, IT IS THE MOST IMPORTANT ORGANELLE IN THE CELL!