Protein folding -3

Protein folding is a process by which a polypeptide chain folds to become a biologically active protein in its native 3D structure. Protein structure is crucial to its function. Folded proteins are held together by various molecular interactions. During translation, each protein is synthesized as a linear chain of amino acids or a random coil which does not have a stable 3D structure. The amino acids in the chain eventually interact with each other to form a well-defined, folded protein. The amino acid sequence of a protein determines its 3D structure. Folding of proteins into their correct native structure is key to their function. Failure to fold properly produces inactive or toxic proteins that malfunction and cause a number of diseases. Four stages of protein folding The folding of a protein is a complex process, involving four stages, that gives rise to various 3D protein structures essential for diverse functions in the human body. The structure of a protein is hierarchically arranged, from a primary to quaternary structure. The wide variation in amino acid sequences accounts for the different conformations in protein structure. Primary structure refers to the linear sequence of amino-acid residues in the polypeptide chain. Secondary structure is generated by formation of hydrogen bonds between atoms in the polypeptide backbone, which folds the chains into either alpha helices or beta-sheets. Tertiary structure is formed by the folding of the secondary structure sheets or helices into one another. The tertiary structure of protein is the geometric shape of the protein. It usually has a polypeptide chain as a backbone, with one or more secondary structures. The tertiary structure is determined by the interactions and bonding of the amino acid side chains in the protein. Quaternary structure results from folded amino-acid chains in tertiary structures interacting further with each other to give rise to a functional protein such as hemoglobin or DNA polymerase. Problem: What is the only level of protein structure that does not involve covalent bonding? A) Tertiary structure B) Secondary structure C) Primary structure D) Quaternary structure How many amino acids are per turn in an alpha helix secondary structure? A) 3.6 B) 1.8 C) 0.4 D) 7.2 E) 10.4 #protein #polypeptide #aminoAcid #peptide #disulfideBridges #covalentBounding #ionicBounding #hydrophobicInteraction #NikolaysGeneticsLessons #proteinStructure #proteinSequence #proteinFolding #aminoAcids #proteins #Polypeptides #ImidazolRing #Histidine #polypeptideChain #oligopeptide #hydrolysesSynthesis #condensationReaction #condensationSynthesis #peptides #globularProteins #fibrousProteins #Genetics