How Proteins Are Made: A Step-by-Step Animation

DNA transcription occurs in the nucleus of the cell, where genetic information is stored in DNA molecules.The DNA double helix contains two strands held together by complementary base pairs.The process begins when RNA polymerase attaches to the DNA and begins to unzip the double helix.As RNA polymerase moves along the DNA template strand, it assembles a complementary strand of messenger RNA, using uracil instead of thymine.The resulting messenger RNA strand carries the genetic instructions needed for protein synthesis.Once transcription is complete, the messenger RNA will be processed and exit the nucleus through nuclear pores.The mRNA strand, carrying the genetic instructions, arrives at the ribosome in the cytoplasm.The ribosome has three important binding sites: the E, P, and A sites.Transfer RNA molecules, or tRNAs, carry specific amino acids and match up with the codons on the mRNA.Each tRNA has an anticodon that pairs with the corresponding codon on the mRNA.As each new amino acid arrives, it forms a peptide bond with the growing chain.The ribosome continues moving along the mRNA strand, reading each codon and adding amino acids to the chain.This process continues until the ribosome encounters a stop codon, signaling the end of protein synthesis.As amino acids are joined together by peptide bonds, they form a linear chain.The protein chain begins to fold based on the chemical properties of its amino acids. Hydrophobic amino acids tend to cluster together, while polar ones face the outside.Special proteins called chaperones help guide this folding process and prevent incorrect interactions.The folded protein then moves to the endoplasmic reticulum for initial processing.After ER processing, the protein moves to the Golgi apparatus for final modifications.The protein reaches its final functional form after all modifications are complete.