The Role of RNA in Gene Expression and Protein Synthesis

Overview

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• Source: Microbioz India


• Date: 21 Dec,2023

A functional gene product, such as a protein or RNA molecule, is synthesized using the information from a gene, an event known as gene expression. In this regard, the DNA of the gene gets transcribed into an mRNA (messenger RNA). Then, eventually with translation, there takes place a transition from mRNA to a fully operating protein.

These processes involve three main types of RNA; messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA (rRNA).

Messenger RNA (mRNA):

1. Transcription: A specific piece of DNA is used to start gene expression, which involves transcribing it into a complementary mRNA strand within the nucleus.
2. RNA Polymerase: Within this process, mRNA synthesis is catalyzed by enzymes called RNA polymerases that add complementary RNA nucleotides on the growing mRNA strand.
3. mRNA Processing: Modifying mRNA including addition of a 5′ cap and a polyA tail occurs before it leaves the nucleus. These changes aid in stabilizing and aiding in its translation in cytoplasm.
4. Transport to the Cytoplasm: After processing, mRNA is taken from the cell nucleus into the cytoplasm where protein synthesis occurs.

Transfer RNA (tRNA):

1. Translation: In cytoplasm, proteins are synthesized with help from tRNA molecules using mRNA as templates for synthesis known as translation. tRNA molecules play a crucial role in this process.
2. Amino Acid Transport: The ribosome carries each tRNA molecule to a specific amino acid involved in protein synthesis within cellular machinery.
3. Anticodon Recognition: The anticodon region base pairs with its complementary codon on mRNAs ensuring that right amino acid will be added to growing polypeptide chain.

Ribosomal RNA (rRNA):

1. Ribosome Structure: Ribosomes are composed of rRNAs and proteins within cells. They function as site for protein synthesis.
2. Catalysis of Peptide Bonds: Peptide bonds between amino acids are facilitated by ribosomes linking them together forming polypeptide chains.
3. Reading the mRNA Code: The ribosome moves along mRNAs reading codons allowing appropriate tRNA molecules bind their corresponding amino acids.

The above process includes gene expression, protein synthesis, and RNA action in the body of a living organism. In this respect, the presence of these three types of RNA meticulously controls the proper transfer of genetic information from DNA to proteins (Alberts et al. 2013). In most cases, it is diagrammatically represented as the central dogma of molecular biology: DNA makes RNA while RNA makes protein.