Question

Write the function of nucleolus?

Answer 1

The nucleolus is an important and prominent organelle within the mammalian nucleus. It's an outsized solid structure inside the nucleus and is assembled around repeated clusters of recombinant DNA genes therefore, a diversity of DNA regions appear to be related to the nucleolus. These regions were identified in human cells by microarray probing and high-throughput sequencing of DNA that co-purifies with nucleoli.

Complete answer:
Nucleolus is a region found within the cell organ. It is primarily related to ribosome biogenesis. Several lines of evidence show that it's additional functions includes regulation of mitosis, cell-cycle progression and proliferation, many styles of stress response, and biogenesis of multiple ribonucleoprotein complexes.
Structure:
The nucleolus isn't membrane enclosed. In eukaryotic cells, nucleolus encompasses a well-ordered structure with four main ultrastructural components namely:
• Fibrillar centers: Formation of ribosomal proteins occurs here.
• Granular components: Before ribosomes are formed, these components have rRNA that binds to ribosomal proteins.
• Dense fibrillar components: It's new transcribed RNA, which connects to the ribosomal proteins.
• Nucleolar vacuoles: It's present only in plant cells.
Functions:
• It is the site of transcription of genes for rRNA molecules.
• It covers nearly 25% volume of the nucleus.
• It plays a crucial role within the synthesis of proteins and the production of ribosomes in eukaryotic cells.
• The nucleolus also appears to stay certain sequences spatially separated. This was observed for budding yeast chromosome XII, which harbors the rDNA gene cluster.

Note: The ultrastructure of the nucleolus can be visualized through a microscope. The arrangement of the nucleolus within the cell is studied by the techniques – fluorescence recovery after photobleaching and fluorescent protein tagging. The nucleolus of several plant species has very high concentrations of iron in contrast to the human and animal cell nucleolus.