RNA

RNA (Ribonucleic Acid)

1. Introduction

- RNA (Ribonucleic Acid) is a nucleic acid involved in coding, decoding, regulation, and expression of genes.

- It is essential for translating genetic information from DNA into proteins.

- Discovered in 1868 by Friedrich Miescher, similar to DNA but with distinct features.

2. Chemical Composition

- Made up of monomers called nucleotides.

- Each nucleotide consists of:

- A ribose sugar (a five-carbon sugar)

- A phosphate group

- A nitrogenous base (Adenine, Uracil, Cytosine, Guanine)

3. Types of RNA

- Messenger RNA (mRNA): Carries genetic information from DNA to the ribosomes for protein synthesis.

- Transfer RNA (tRNA): Brings amino acids to ribosomes during translation.

- Ribosomal RNA (rRNA): Forms the core of ribosomes and catalyzes protein synthesis.

- Other types: Small nuclear RNA (snRNA), microRNA (miRNA), and long non-coding RNA (lncRNA) involved in regulation and processing.

4. Structure of RNA

- Usually single-stranded.

- Composed of a chain of nucleotides.

- The sugar in RNA is ribose, which has an extra hydroxyl group (-OH) at the 2' carbon compared to DNA.

- Contains the nitrogenous base Uracil (U) instead of Thymine (T).

5. Nitrogenous Bases in RNA

- Adenine (A)

- Uracil (U)

- Cytosine (C)

- Guanine (G)

6. Functions of RNA

- Protein synthesis: mRNA, tRNA, and rRNA work together during translation.

- Gene regulation: microRNA and other non-coding RNAs regulate gene expression.

- Catalytic roles: Some RNA molecules (ribozymes) have enzymatic activity.

- Viral genomes: Many viruses use RNA as their genetic material.

7. RNA Synthesis (Transcription)

- DNA is transcribed into RNA by RNA polymerase.

- Occurs in the nucleus (in eukaryotic cells).

- The process involves:

- Initiation at promoter regions.

- Elongation of the RNA strand by addition of complementary ribonucleotides.

- Termination when the RNA transcript is complete.

8. RNA Processing (in Eukaryotes)

- Pre-mRNA undergoes modifications:

- Capping: Addition of a 5' cap.

- Polyadenylation: Addition of a poly-A tail at the 3' end.

- Splicing: Removal of introns and joining of exons.

9. Role in Protein Synthesis

- mRNA carries genetic information from DNA.

- tRNA transports amino acids to the ribosome.

- rRNA forms part of the ribosome's structure and catalyzes peptide bond tion

11. Viral RNA

- Many viruses (e.g., influenza, HIV) have RNA genomes.

- Can be single-stranded or double-stranded.

- Replicated and transcribed by viral enzymes.

12. RNA Technologies

- Reverse transcription: RNA can be reverse-transcribed into DNA (used in HIV research).

- RNA interference (RNAi): A process to silence gene expression.

- RNA sequencing: Determines the sequence of RNA molecules.

13. Importance of RNA

- Central in gene expression.

- Used in biotechnology, medicine, and research.

- Target for antiviral drugs and gene therapy.