Cells are the structural and functional units of living beings and can be divided into two large groups: prokaryotes and eukaryotes. These two cells are mainly differentiated by the way the genetic material is arranged in their structure. In prokaryotic cells, the DNA (deoxyribonucleic acid) is in a membraneless region called the nucleoid. In the eukaryotic cell, the DNA is found surrounded by a double membrane, forming the core. Inside the nucleus, we find the nucleolus.
→ What is the nucleolus?
The nucleolus is a region that can be seen inside the nucleus and has a rounded shape. The nucleolus is formed mainly byRNA ribosomal and proteins. This RNA is synthesized from DNA instructions. Some cells have two or more nucleoli, this number being related to the type of cell and its reproductive stage.
In the nucleolus, ribosomal subunits are formed. For this to happen, proteins imported from the cytoplasm must bind to rRNA, leading to the formation of large and small subunits that form a ribosome
. These subunits then migrate from the nucleus, through the pores that exist in the nuclear membrane, and reach the cytoplasm. In this region, the large and small subunits can join together and form the ribosome.Do not stop now... There's more after the advertising ;)
→ What is a ribosome?
Ribosomes are structures present in cells that are formed from ribosomal RNA and some proteins. As they do not have membranes, these structures are not considered organelles by some authors. In eukaryotic cells, ribosomes can be found suspended in the cytosol or even adhered to the membrane of the endoplasmic reticulum and nuclear membrane.
In these structures, proteins are formed. In cells with high rates of protein synthesis, the number of ribosomes is quite high. As an example of this information, we can mention the cells of the pancreas, which are responsible for a great synthesis of digestive enzymes. In these cells, in addition to a large number of ribosomes, we also observe well-developed nucleoli.
Learn more about ribosomes clicking here!
By Ma. Vanessa dos Santos
Would you like to reference this text in a school or academic work? Look:
SANTOS, Vanessa Sardinha dos. "What is the nucleolus?"; Brazil School. Available in: https://brasilescola.uol.com.br/o-que-e/biologia/o-que-e-nucleolo.htm. Accessed on June 28, 2021.
