Answer:
The α‑helix is held together by hydrogen bonds between the amide N−H and C=O groups.
Disulfide bonds stabilize secondary structure.
Explanation:
Proteins have primary, secondary, tertiary and quartinary structures.
The secondary structure of a protein is the regular, recurring sequence of amino acid in a polypeptide chain. Secondary structure of proteins give rise to the folding observed in the structure of a protein.
The major secondary structures of a protein are α-helices and β-structures.
This phenomenon is known as the periodic trends in reactivity. It occurs because of the arrangement of electrons in orbitals.
As one moves from left to right across a period, the number of electrons in the outermost shell increases. These outermost electrons are involved in chemical reactions.
Therefore, as the number of outermost electrons increases, the reactivity of the element increases. However, the elements have filled shells, so beyond a certain point, the outermost shell will be full.
The reactivity then decreases as the electrons are no longer available to take part in chemical reactions. Therefore, the reactivity of the elements decreases from left to right in a period and then increases as the outermost shell begins to fill up again.
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The answer is (3) 11,460 y. For this problem, you must know that the half life of C-14 is 5740 y and that nuclear decay processes are first order reactions (which means that the half life remains constant). For 25.00g to be left of a 100.0g sample, two half life must have elapsed (100*0.5*0.5=25). Each half life is 5730 y, so the total time elapsed is 5730 * 2 = 11,460 y.
