Genetics-And-Evolution-Molecular-Basis-Of-Inheritance-2

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.