Question

Nucleolus are rich in
A. Deoxy ribonucleoprotein
B. Lipoprotein
C. Ribonucleoprotein
D. mRNA and rRNA

Answer 1

Nucleolus is a distinct structure present in the nucleus. They are primarily responsible for producing and assembling cell’s ribosomes. It is best known as the site of ribosome biogenesis.

Complete answer:
Option A: Deoxy ribonucleoprotein is a complex of DNA and protein. Nucleosome, the genomic DNA of eukaryotic, which is wrapped around histone octamers is a classical example of this. Deoxy ribonucleoprotein is present inside the nucleus. Therefore, this is the incorrect option.

Option B: Lipoprotein is a complex of lipids and proteins. They are responsible for the transport of hydrophobic lipids in blood plasma. Also, many enzymes, antigens, and adhesin are lipoproteins. They are present in the blood plasma. Therefore, this is the incorrect option.

Option C: Ribonucleoprotein is a complex of ribonucleic acid and RNA binding proteins. They are an integral part of transcription, translation, and regulation of gene expression. They are present in the nucleus and cytoplasm. Therefore, this is the incorrect option.

Option D: mRNA and rRNA are messenger RNA and ribosomal RNA respectively. Ribosomal RNA is the primary component of the ribosome which carries out protein synthesis. rRNA is synthesized in the nucleosome, with the help of RNA-polymerase 1 from rDNA. Messenger RNA is the correspondent transcript of a gene that is read by ribosomes to synthesize protein. They are known to localize on nucleolus. mRNA and rRNA are present in the nucleolus. Therefore this is the correct option. The nucleolus is the largest structure inside the nucleus and is made up of protein, DNA, and RNA. They are known as the site of ribosome biogenesis and also play a part in regulating the stress response of the cells.

Hence, the correct answer is option ‘D’ i.e, mRNA and rRNA.

Note:
i) Nucleolus was originally classified as chromatin because of the basophilic nature.
ii) Later they were excluded because they were rich in RNA instead of DNA.
iii) Nucleolo Patties are the conditions found in humans because of the malfunction of the nucleolus.