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The primary function of which globular structure is to produce and assemble the ribosomes of the cell?
Chromatin
Nucleolus
Centriole
Peroxisomes
Nucleolus
The nucleolus is a dense, spherical, non-membrane-bound structure located within the nucleus of eukaryotic cells. It serves as the primary site for the transcription of ribosomal RNA (rRNA) and the assembly of ribosomal subunits.
The nucleolus is a dense, spherical, non-membrane-bound structure located within the nucleus of eukaryotic cells. It serves as the primary site for the transcription of ribosomal RNA (rRNA) and the assembly of ribosomal subunits.
If the cell is a factory, the nucleus is the head office, and the nucleolus is the specialized 'assembly line' that manufactures the machinery (ribosomes) needed for the actual production of goods (proteins).
N for Nucleolus = N for New Ribosomes.
80S┬аribosome=60S┬а(large┬аsubunit)+40S┬а(small┬аsubunit) тАФ representing the composition of eukaryotic ribosomes.
The process begins with the transcription of rRNA genes by RNA polymerase I. These rRNA molecules are then processed and assembled with ribosomal proteins, which are imported from the cytoplasm, to form the large and small ribosomal subunits. Once assembled, these subunits are exported through nuclear pores into the cytoplasm, where they associate to form functional 80S ribosomes during protein synthesis.
The nucleolus is not enclosed by a membrane.
It disappears during the prophase of mitosis and reappears during telophase.
Ribosomes are essential for translating mRNA into polypeptide chains.
Cells with high protein synthesis requirements (e.g., pancreas cells) possess prominent nucleoli.
Used as an indicator of cellular protein synthesis activity.
Relevant in studying ribosome biogenesis related to cellular growth and stress.
The nucleolus is typically found in eukaryotic cells; prokaryotes lack a nucleolus as they do not have a membrane-bound nucleus.
Option A (Chromatin): Complex of DNA and proteins that forms chromosomes, not the site of ribosome assembly.
Option C (Centriole): Cylindrical structures involved in organizing microtubule assembly during cell division.
Option D (Peroxisomes): Organelles involved in lipid metabolism and detoxification of hydrogen peroxide (H2тАЛO2тАЛ).
B is correct тАФ The nucleolus is the specialized sub-nuclear domain responsible for the synthesis of ribosomal RNA and the assembly of ribosomal subunits.
In competitive exams, remember that the nucleolus is often described as a 'factory within a factory' regarding protein synthesis machinery.
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