α-Keratin is an intermediate filament with a basic structural unit of two a helices in a coiled coil. Each helix has a seven-residue repeating unit (heptad repeat). A representation of the a helices of a coiled coil dimer is shown. Each letter represents a different amino acid residue. f g d e Review the table of amino acids. a d g f Identify the three true statements about the structure of keratin. ☐ The a helix of the coiled coil is wound less tightly than predicted for an α helix. ☐ Each polypeptide in the dimer has 3.6 residues per turn, and a nonpolar group occurs every 3.5 residues, resulting in a slight winding, or twist, around the other polypeptide, forming a coiled coil. Arg-Ala-His-Glu-His-Thr-Asp is a likely repeat in the a helix of keratin. ☐ Val-Thr-Asp-Ala-Glu-Arg-His is a likely repeat in the a helix of keratin. ☐ The residues at positions b and c are less likely to be polar or charged because they are in contact with the solvent. ☐ Keratin molecules are very strong due to hydrophilic interactions between charged amino acid side chains.

"Potassium Bromate (KBr03) is added to flour as a softener that strengthens the texture of bread. It can do this by forming disulfide bonds between two cysteine amino acids in a reaction similar to the chemical equation given below. The function of KBr03 is to remove the 2 electrons needed to form the disulfide bond as shown in the figure below. Each of the cysteine amino acids will be in a protein chain, so the reaction binds the two chains together, giving the dough cohesion. However, potassium bromate is a proven carcinogen and is only allowed in foods in the United States because bakers will add the right amount and correct It has been assumed to meet the temperature and cooking time conditions. " KBRO, + C,H¸NO,SH → KBr + H,O+C,H„N,O,S, Balance the reaction of potassium bromate (KBr03) with the cysteine molecule (C3H6 NO2 SH) by converting it into the reduced step matrix using the additive matrix method. (Kis the symbol of potassium in the question) (Homogeneous linear equation…

Which of the following amino acids would you least expect to find on the surface of a water-soluble protein? Explain I Serine Glutamat Lysime Threonine