Types of RNA and the Process of Transcription

What Is RNA?

RNA is a very important molecule because it plays many biological roles, particularly in the synthesis of proteins. Yet, it is very different from DNA because it plays dynamic functions in the cell where it serves as a messenger, a structural component, and a chief controller of gene expression in numerous biological ways. Knowledge of the various forms adopted by RNA is central to understanding how genetic information is applied to perform cellular functions.

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This Story also Contains

1. What Is RNA?
2. Messenger RNA (mRNA)
3. Ribosomal RNA (rRNA)
4. Transfer RNA (tRNA)
5. Small Nuclear RNA (snRNA)
6. MicroRNA (miRNA)
7. Other Kinds Of RNA
8. Comparative Table Of RNA Types
9. The Video Recommended for Types Of RNA

Messenger RNA (mRNA)

It is the RNA that carries the genetic message from the DNA to the ribosome for protein synthesis.

mRNA Structure

• It is a single-stranded molecule and has a structure that is capped at 5'- and tailed at 3' - with a Poly-A tail at the 5'- end

mRNA function

• It carries a genetic message from DNA to the ribosome, this message will be read by the ribosome for protein synthesis.

• It is a template used in the translation stage of protein synthesis - for the assembling of amino acids into proteins.

mRNA Synthesis (Transcription)

• It is a product of a transcription process in which RNA polymerase transcribes the DNA.

• Before there is any translation, this mRNA can undergo processing in which it is modified through a process known as capping, splicing, and polyadenylation.

Applications Of mRNA

• It is used in mRNA vaccines, such as those for COVID-19.

• It has potential use in gene therapy and other biotechnological applications.

Ribosomal RNA (rRNA)

Another primary cellular component that plays a critical role in the creation of proteins is the ribosome.

rRNA Structure

• Makes up the ribosome along with proteins that help the rRNA form the ribosome along proteins

• It is of different sizes, 18S, 28S.

rRNA Functions

• Forms peptide linkages among amino acids.

• Supplies the right orientation between messenger RNA and transfer RNA during protein synthesis.

rRNA Genes And Ribosomal Structure

• The rRNA genes are transcribed to produce the ribosomal units.

• The construction of ribosomes is dependent on the availability of rRNA as well as ribosomal assembly.

Clinical Significance

• Antibiotics can impede protein synthesis in prokaryotes by attacking ribosomal RNA.

• Diseases, including Ribosomopathies, are caused by duet attributed to mutations of the rRNA genes.

Transfer RNA (tRNA)

• It performs the role of carrying amino acids into the ribosome while synthesising proteins.

Structure Of tRNA

• The secondary structure is cloverleaf and has an anticodon loop and an amino acid binding site.

Functions Of tRNA

• The appropriate amino acid is brought in by pairing the anticodon of t RNA with the mRNA codon.

• It translates the genetic code into proteins.

Aminoacylation Of t RNA ( charging )

• The aminoacyl-t RNA synthetase charges the t RNA with an amino acid.

• Accurate synthesis of proteins is possible only when t RNA is charged.

Clinical Significance Of tRNA

• Mitochondrial diseases may occur due to mutation in t RNA.

• Applied in synthetic biology in the development of new kinds of proteins.

Small Nuclear RNA (snRNA)

snRNA is essential for the splicing of pre-mRNA as part of the process of maturation of mRNA.

Structure And Composition of snRNA

• Small RNA molecules combine with proteins to create spliceosomes.

• Schematic of snRNA in a spliceosome.

The function Of snRNA

• Allows for the removal of introns from pre-mRNA.

• Ensures the splicing takes place properly, for proper formation of mRNA.

Varieties Of snRNA

• Includes U1, U2, U4, U5, U6, each with a specific function in splicing.

• Each kind assists in recognising the splice sites and, therefore, catalyses the act of splicing.

Clinical Relevance Of snRNA

• Splicing errors can cause genetic anomalies.

• snRNA is currently being researched as a possible target for therapy.

MicroRNA (miRNA)

miRNA are small non-coding RNAs that function to block gene expression by binding to mRNA causing their degradation or translating inhibition.

Structure Of miRNA

• Small RNA molecules produced from long precursors, known as pri-miRNA, are a shorter sequence of RNAs.

• Regulates gene expression after it is transcribed.

• Combined with complementary sequences of the mRNA, represses translation or activates degradation.

Clinical Relevance Of miRNA

• It is involved in many diseases, especially cancer.

• Therapeutic potentials exist with the manipulation of the expression of the gene with the help of miRNA mimics or inhibitors.

Diagrams: Types Of RNA

Other Kinds Of RNA

There are also a few other kinds of RNA molecules besides the ones mentioned above, which have their functions and significance in the cell.

Small Interfering RNA

• Small, double-stranded RNA plays a role in RNA interference.

• Used in gene silencing and research applications.

Long Non-Coding RNA (lncRNA)

• Non-coding RNAs are the longer RNA molecules that do not code for proteins.

• Function in gene regulation, chromatin remodelling and in processes of diseases.

Ribozymes And Catalytic RNA

• Molecules of RNA with enzymatic activity.

• Participate in RNA splicing and reactions of self-cleavage.

Comparative Table Of RNA Types

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