Nucleus
A nucleus (nucleus of a nucleated cell) is a specific organelle of eukaryotes containing almost the entire cellular genome. It is delimited by a nuclear envelope which is a double membrane in continuity with the rough endoplasmic reticulum and lined on its internal face with a network of intermediate filaments (nuclear lamina). The exchanges between the nucleus and the cytoplasm are made by nuclear pores. The nucleus contains the nucleoplasm, chromatin, nucleolar (s) and primary transcripts. During cell division, the chromatin condenses and the nuclear envelope disintegrates (except rare cases).
Ribosome
The role of ribosomes is the synthesis of proteins from mRNA.
Proteins, which shape the phenotype of any organism and are functional units (enzymes), are synthesized during highly specific matrix reactions.
During this gene expression, the hereditary message, written in the sequence of deoxyribonucleotides, undergoes a conversion: it is finally reproduced in the amino acid sequence of the proteins since, according to the genetic code, each triplet of nucleotides corresponds to an acid amine.
The fidelity of the expression of the genes is entrusted to the ribosomes: indeed, it is to these particles that the mRNA transmits the message from the genome.
Endoplasmic reticulum
The endoplasmic reticulum (the granular one) is a system of more or less dilated cavities and canaliculus that communicates with each other, carrying ribosomes attached on their outer faces representing 20 to 60% of the surface of the membranes (depends on the cell type). It is more abundant in important protein secretory cells. It is continuous with the nuclear envelope and with the smooth endoplasmic reticulum.
Synthesis and translocation of membrane proteins and secretory proteins with sorting signals.
Golgi apparatus
The Golgi apparatus is an organelle grouping together all dictyosomes (formations consisting of stacked saccules or cisterns). It is a compulsory place for the passage of proteins synthesized by the rough endoplasmic reticulum (granular).
He intervenes in:
1- Transfer of RER proteins to secretory vesicles
2- Protein Maturation
3- Sulfation of glycolipids and synthesis of proteoglycans and glycolipids
4- O-glycosylation of certain proteins.
5- The shipment of secreted products