Keratin is an intermediate filament with a basic structural unit of two helices

Question

Keratin is an intermediate filament with a basic structural unit of two helices in a coiled coil. Each helix has a seven residue repeating unit (heptad repeat). A representation looking down the helices of a coiled coil dimer is shown below. Each letter represents a different amino acid residue 0 Identify the true statements about the structure of keratin. Click here to view a table of the amino acids. The consequence of the coiled coil is that each alpha-helix in the dimer is wound tighter, has a smaller rise per turn, and twists around the other polypeptide. The N-terminus of one helix is aligned with the C-terminus of the other helix in the dimer 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. Glu-Gly-Lys-Thr-Lys-Lys-Ser is a likely repeat in the a helix of keratin. Val-Lys-Arg-Gly-Thr-Glu-Lys is a likely repeat in the a helix of keratin.

Explanation / Answer

First and second statements are true.Rest all are false as alpha helix possess hydrophobic interaction among apolar molecules,and amino acid sequence is also different.

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