RNA Overview
RNA: Ribonucleic Acid, involved in protein synthesis and gene regulation.
Distinct from DNA: More flexible, less stable, involved in active cell processes.
RNA Components
Sugar: Ribose, with an additional hydroxyl group compared to DNA’s deoxyribose.
Nitrogenous Bases: Adenine (A), Guanine (G), Cytosine (C), Uracil (U).
Nucleoside: Ribose sugar + nitrogenous base (without phosphate group).
RNA Structure
Polynucleotides: Long chains of nucleotides linked by phosphodiester bonds.
Structure: Typically single-stranded, can form complex 3D structures like hairpins.
Special Features
Uncommon Nucleotides: Modified bases for stability and function.
Ribothymidine: Modified nucleotide in tRNA for accurate mRNA reading.
Types of RNA
mRNA: Messenger RNA, carries genetic info from DNA to ribosomes.
tRNA: Transfer RNA, brings specific amino acids to ribosomes for protein synthesis.
rRNA: Ribosomal RNA, structural and enzymatic component of ribosomes.
snRNAs: Small Nuclear RNAs, involved in pre-mRNA splicing.
miRNAs: microRNAs, regulate gene expression post-transcriptionally.
Catalytic RNA: Ribozymes capable of catalyzing chemical reactions.
Key Distinctions
Thymine vs. Uracil: Thymine in DNA for stability; Uracil in RNA.
Stability: DNA more stable due to deoxyribose and thymine.
Evolutionary Theory: “RNA world” hypothesis suggests RNA evolved before DNA.
