RNA is a type of ribonucleic acid that assists in the body’s synthesis of proteins. In the body of a human, this nucleic acid is in charge of creating new cells. It is often generated from the DNA molecule. The sole difference between RNA and DNA is that RNA only has one strand, whereas DNA has two and only one ribose sugar molecule.
All cells require ribosomes, the main building block of non-coding RNA known as ribosomal ribonucleic acid (rRNA). To create the large and small ribosome subunits, ribosomal RNA is translated from ribosomal DNA (rDNA).
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What is Ribosomal RNA
The RNA found in ribosomes, the molecules responsible for catalysing protein synthesis, is known as ribonucleic acid (rRNA). Over 60-80% of the weight of the ribosome is composed of ribosomal RNA, essential for all of the ribosome’s activities, including binding to mRNA, attracting tRNA, and catalysing the formation of peptide bonds between amino acids.
The three-dimensional structure of an rRNA core influences the structure of a ribosome. Through their interactions with the core, ribosomal proteins help to maintain this structure.
The nucleus has unique structures known as nucleoli, where ribosomal RNA is translated. These are spherical, dense structures that develop around rRNA-coding genes. The eventual synthesis of ribosomes depends on nucleoli’s retention of ribosomal proteins.
Types of rRNA
In Prokaryotes
In prokaryotes, the 16S ribosomal RNA is housed in a compact 30S ribosomal subunit. Two rRNA species are present in the large 50S ribosomal subunit (the 23S and 5S ribosomal RNAs). Therefore, it may be concluded that a single rRNA gene in archaea and bacteria codes for the three rRNA types: 16S, 23S, and 5S.
The bacterial 23S, 16S, and 5S rRNA genes are commonly arranged as a co-transcribed operon.
In Eukaryotes
The eukaryotic ribosome is composed of the 40S and a 60S subunit. Eukaryotes, in contrast, usually have several variants of the rRNA genes arranged in repetitive sequences. About 300-400 repeats are found in five clusters on human chromosomes: 13 (RNR1), 14 (RNR2), 15 (RNR3), 21 (RNR4) and 22 (RNR5).
Furthermore, chloroplasts and mitochondria in eukaryotic cells both contain rRNA. Ribosomes can be found in the cytoplasm as free-floating complexes or connected to the endoplasmic reticulum.
Functions of rRNA
Protein synthesis is the primary function of rRNA. The A, P, and E sites are created within the ribosome by the unusual three-dimensional structure of rRNA, which has internal helices and loops. By attaching to messenger RNA and transfer RNA, these molecules assure that the codon sequence of the mRNA is appropriately translated into the amino acid sequence of proteins.
The A site anchors an entering tRNA that has been charged with an amino acid, while the P site is for binding a developing polypeptide. The tRNA temporarily attaches to the E site following the creation of a peptide bond before exiting the ribosome.
In addition, some ribosomal proteins can bind to rRNA at specific residues, which have been identified after detailed investigation for both the RNA and protein.
Antibiotics like streptomycin and tetracycline have recently been identified as having binding sites on bacterial rRNA. For example, a mutation in the 16S rRNA sequence is the tolerance of Euglena and Escherichia coli to streptomycin.
The 30S rRNA appears to be the source of tetracycline resistance. Similar findings were discovered for Streptomyces to Spectinomycin resistance.
Preribosomal RNA, one of rRNA’s predecessors, has been linked to the production of microRNA, which mediates inflammation and heart illness concerning mechanical stress. This finding adds a new dimension to the role of rRNA.
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