ribosoomidega

Ribosomes are essential molecular machines found in all living cells, responsible for protein synthesis. They are composed of ribosomal RNA (rRNA) and proteins, organized into two subunits: a large subunit and a small subunit. These subunits come together to form a functional ribosome during the process of translation.

The small subunit primarily binds to messenger RNA (mRNA), the molecule that carries the genetic code transcribed from DNA. It then positions the mRNA correctly for reading. The large subunit contains the catalytic site for forming peptide bonds, the chemical links that connect amino acids together to create a polypeptide chain, which folds into a functional protein.

Ribosomes can be found free in the cytoplasm, where they synthesize proteins that will function within the cell, or attached to the endoplasmic reticulum, forming the rough endoplasmic reticulum. Proteins synthesized on bound ribosomes are typically destined for secretion from the cell, insertion into membranes, or delivery to specific organelles like lysosomes.

The process of protein synthesis, or translation, involves the ribosome moving along the mRNA molecule, reading its codons (three-nucleotide sequences) and recruiting the corresponding transfer RNA (tRNA) molecules, each carrying a specific amino acid. The ribosome catalyzes the formation of peptide bonds between these amino acids, elongating the polypeptide chain until a stop codon is reached on the mRNA, signaling the termination of translation.