Structure
Single-Stranded
RNA is typically single-stranded, but it can form secondary structures by folding upon itself.
Backbone: Each strand consists of a sugar-phosphate backbone, with the sugar being ribose.
Bases: RNA contains adenine (A), uracil (U), cytosine (C), and guanine (G), with A pairing with U in complementary base pairing.
Secondary Structures: RNA can form hairpins, loops, and other complex structures through intramolecular base pairing.
Types of RNA
mRNA (Messenger RNA): Carries genetic information from DNA to ribosomes for protein synthesis.
tRNA (Transfer RNA): Transfers specific amino acids to the ribosome during protein synthesis.
rRNA (Ribosomal RNA): Structural and functional component of ribosomes, where proteins are synthesized.
Other RNAs: Includes small nuclear RNA (snRNA), microRNA (miRNA), and others involved in regulation and processing.
Functions
Messenger RNA (mRNA)
Transcription: mRNA is synthesized from a DNA template during transcription.
Translation: mRNA is translated into a protein sequence by ribosomes in the cytoplasm.
Transfer RNA (tRNA)
Amino Acid Transport: tRNA molecules transport amino acids to the ribosome.
Codon-Anticodon Interaction: Each tRNA has an anticodon that pairs with a complementary codon on the mRNA, ensuring the correct amino acid is added to the growing polypeptide chain.
Ribosomal RNA (rRNA)
Ribosome Structure: rRNA molecules combine with proteins to form ribosomes.
Catalysis: rRNA catalyzes the formation of peptide bonds between amino acids during protein synthesis.
Regulatory RNAs
miRNA and siRNA: These small RNAs regulate gene expression by degrading mRNA or inhibiting translation.
snRNA: Involved in splicing pre-mRNA to remove introns and join exons.
Difference between DNA and RNA
Feature | DNA | RNA |
Strand Structure | Double-stranded | Single-stranded (usually) |
Sugar | Deoxyribose | Ribose |
Bases | Adenine (A), Thymine (T), Cytosine (C), Guanine (G) | Adenine (A), Uracil (U), Cytosine (C), Guanine (G) |
Base Pairing | A-T, C-G | A-U, C-G |
Functions | Genetic information storage, replication, gene expression regulation | Protein synthesis (mRNA, tRNA, rRNA), gene regulation (miRNA, snRNA) |
Stability | More stable | Less stable |
Location | Nucleus (in eukaryotes), mitochondria | Nucleus, cytoplasm, ribosomes |