Ribonukleiidi

Ribonukleiidi, commonly known as RNA, is a vital nucleic acid molecule essential for various biological functions within all living cells. It is a polymer composed of a chain of nucleotides. Each nucleotide consists of a ribose sugar, a phosphate group, and one of four nitrogenous bases: adenine (A), guanine (G), cytosine (C), or uracil (U). Unlike its close relative deoxyribonucleic acid (DNA), RNA typically exists as a single strand and contains uracil instead of thymine.

The primary roles of RNA in the cell are diverse and critical. Messenger RNA (mRNA) carries genetic information transcribed from DNA in the nucleus to the ribosomes in the cytoplasm, where it serves as a template for protein synthesis. Transfer RNA (tRNA) molecules are responsible for bringing specific amino acids to the ribosome during protein synthesis, matching them to the codons on the mRNA. Ribosomal RNA (rRNA) is a structural component of ribosomes, the cellular machinery responsible for translating mRNA into proteins.

Beyond protein synthesis, RNA plays other important roles. Small nuclear RNAs (snRNAs) are involved in RNA splicing, a process that removes non-coding regions from pre-mRNA. MicroRNAs (miRNAs) and small interfering RNAs (siRNAs) are regulatory RNAs that can silence gene expression by binding to complementary mRNA molecules. RNA viruses, such as the influenza virus and HIV, use RNA as their genetic material. The versatility of RNA highlights its fundamental importance in the molecular biology of life.