What is RNA? & Types of RNA , Structure and Function.

What is RNA?

RNA stands for Ribonucleic Acid. It is a single-stranded molecule made up of nucleotides( A, U, C, G) and plays a crucial role in gene expression and protein conformation. Analogous to DNA, but it contains ribose sugar( rather than deoxyribose), has uracil( U) rather than thymine( T) generally single-stranded. RNA is a vital biomolecule involved in various cellular functions, especially protein synthesis. If the number of deleted bases is not a multiple of three, then a change in the reading frame will occur, and every codon that follows will be altered. This often results in a completely different and nonfunctional protein. If only three nucleotides (or multiples of three) are deleted, only one or more amino acids will be lost, and the change may not have as serious an effect. Deletion mutations can cause serious genetic disorders, depending on the size and position of the deletion from the gene.

Types of RNA.

There are three main types of RNA.

Messenger RNA (mRNA )
Transfer RNA (tRNA )
Ribosomal RNA (rRNA )

1. mRNA – Messenger RNA.

mRNA is a single-stranded molecule of RNA.
They are synthesized in the nucleus of eukaryotic cells during a process called transcription.
Its sequence is complementary to the DNA template strand it was transcribed from.

Function of mRNA.

Transcription: DNA stands to make mRNA in the nucleus. The enzyme RNA polymerase helps build the mRNA strand.
Transport: When they are formed, mRNA leaves the nucleus and enters the cytoplasm
Translation: Ribosomes read the mRNA sequence in sets of three bases (codons). Each codon corresponds to a specific amino acid.

2. tRNA – Transfer RNA.

tRNA is a small RNA molecule that helps build proteins by bringing the correct amino acids to the ribosome.
It acts like a delivery truck that picks up amino acids and brings them to the protein assembly line.

Structure:

It folds into a cloverleaf shape with three hairpin loops. The most important parts are:
The anticodon loop
The amino acid attachment site

Transfer RNA — Photo by Christinelmiller via Wikimedia Commons, CC BY-SA 4.0

Function of tRNA.

Carries specific amino acids: Each tRNA molecule attaches to one particular amino acid that matches its anticodon sequence.
Helps build proteins:
At the ribosome, tRNAs bring amino acids in the correct order, where they are linked together to form a protein chain.
Decodes the mRNA sequence:
The anticodon on tRNA pairs with the complementary codon on the messenger RNA (mRNA) strand. This ensures the right amino acid is added according to the genetic code.

3. rRNA – Ribosomal RNA.

rRNA stands for ribosomal RNA.
It’s a type of RNA that forms the structure and function of ribosomes, the cell’s protein-making machines.
Ribosomal RNA is a very important type of RNA in most cells.

Structure:

Single-stranded RNA:

rRNA is made of nucleotides, like all RNA, but it folds into complex 3D shapes due to internal base pairing.

Folded Shape:

Forms stems, loops, and helices, resulting in a highly structured molecule.
These folds are essential for forming the core of the ribosome.
Two types of subunit: In prokaryotes and eukaryotes.

1- Prokaryotic Ribosome (70S)

Found in bacteria and archaea.
Made up of two subunits: 30S (small) and 50S (large).

2. Eukaryotic Ribosome (80S)

Found in plant, animal, and fungal cells.
Made up of: 40S (small) and 60S (large) subunits.

Ribosomal RNA — Photo by Christinelmiller via Wikimedia Commons, CC BY-SA 4.0

Function of rRNA.

1. Structural Role:

rRNA forms the backbone of the ribosome.
Provides the scaffold that ribosomal proteins bind to.
They help to create its shape and stability of the ribosome.

2. Catalytic Role (Enzymatic function):

rRNA is a ribozyme — it catalyzes the formation of peptide bonds between amino acids.
Especially the 23S (prokaryotes) or 28S (eukaryotes) rRNA in the large subunit carries out this function.

3. Functional Sites: