how does an alpha helix form, and it which structure does this formation occur?
within the secondary structure, when the hydrogen, nitrogen and oxygen atoms of the basic repeating structure interact, hydrogen bonds may form within the amino acid chain, this pulls the chain into a coil shape called an alpha helix
how and when are beta pleat sheets formed?
within the secondary structure polypeptide chains can lie parallel to one, joined by hydrogen bonds. This form sheet like structures, the pattern formed by individual amino acids causes the structures to appear pleated!
describe what is meant by the term tertiary structure when describing protein formation?
folding of the protein into its final shape. the folding or coiling of proteins in their secondary structure brings R-groups of different amino acids together, so they are close enough to interact and further folding will occur.
x4 different interactions which occur between R- groups?
hydrophobic and hydrophilic interactions, weak interactions between polar and non polar R groups
hydrogen bonds, weakest bonds formed e.g in some of collagens structures
ionic bonds, stronger than hydrogen bonds, form between oppositely charged R groups
disulfide bonds/ disulfide bridges, covalent and the strongest bonds formed- only form between R groups which contain sulfur atoms e.g present in keratin, due to a large proportion of cytenise (the sulphur containing amino acid) resulting in many strong dislufide bridges
