Let's break down your questions regarding amino acids, proteins, and their functions:
e. The amino acids we must be certain to include in our diet are called essential amino acids. These are amino acids that our bodies cannot synthesize on their own, necessitating their intake through food.
f. A protein’s function is indeed influenced by its three-dimensional shape: i. Cells build proteins by linking amino acids together by a peptide bond. This bond forms between the carboxyl group of one amino acid and the amino group of another, releasing a molecule of water in the process (a dehydration synthesis reaction). ii. The order of the amino acids, as well as the overall shape of the protein, impacts how that protein functions. The specific sequence of amino acids (primary structure) determines the protein's folding and final shape (secondary, tertiary, and sometimes quaternary structures).
iii. The structure levels of proteins are:
- Primary structure: The linear sequence of amino acids in a polypeptide chain.
- Secondary structure: Local folded structures that form within a protein due to hydrogen bonding, such as alpha helices and beta sheets.
- Tertiary structure: The overall three-dimensional shape of a single polypeptide chain, formed by the interactions among the various side chains (R groups) of the amino acids.
- Quaternary structure: The arrangement of multiple polypeptide chains into a single functional unit. Not all proteins have quaternary structure; it's present in proteins made up of more than one polypeptide chain.
g. If, at any time, something alters the shape of the protein, it can lead to denaturation, meaning the protein will no longer be able to function properly. Denaturation can occur due to changes in temperature, pH, or the presence of certain chemicals, which can disrupt the interactions responsible for maintaining the protein's structure. This, in turn, can affect various cellular functions and processes.