Keratin is an intermediate filament with a basic structural unit of two helices
ID: 149353 • Letter: K
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.
Please explain why the the answers are correct and why the others are wrong.
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. 9 0 Identify the true statements about the structure of keratin. Click here to view a table of the amino acids. Lys-Gly-Glu-Ser-Glu-Arg-Lys is a likely repeat in the a helix of keratin 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. 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. Val-Arg-His-Gly-Ser-Lys-Glu is a likely repeat in the a helix of keratin.Explanation / Answer
The first statement is correct, because in the amino acid sequence of alpha keratin the 7th amino acid is always lysine.Therefore statement 1 is correct.
The second statement true.As N- terminal is the start site and C- terminal the end.In alpha helix, the terminal of one helix aligns with the opposite terminal on other helix i.e they are antiparallel.
The third statement is false, because as the amino acids b and c are present in solvent , they have to be charged , more polar as they have to form hydrophilic interactions.
The fourth statement is true (reason given in 3)
The fifth statement is also true.
The sixth statement is false (reason given in 1).
Hope it explains your query, Good luck !!!
Please do press like !!! :)
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.