3. Proteins
Proteins make up 12-18% of the body and consist primarily of Carbon, Hydrogen, Oxygen and Nitrogen . They are large molecules that carry out complex functions and are amphipathic . They are made up of smaller molecules called amino acids.
Functions :
Form structural framework (ex: collagen & keratin)
Function as hormones, regulate physiological processes, control growth/development, mediate responses of the nervous system (ex: insulin) Allow muscle contraction (ex: myosin and actin) Immunological: aid in responses to foreign substances (ex: antibodies) Transport: carry vital substances throughout the body (ex: hemoglobin) Catalysts: act as enzymes and function in regulation of biochemical reactions (ex: amylase, lipase and lactase)
Protein Structure : Amino acid – Peptide – Polypeptide – Protein
Amino Acids (AA)
20 types (10 essential, 10 non-essential) building blocks of proteins made up of central carbon – C, amino group (NH2), a carboxyl group (COOH) and a side chain ‘R’ (is different for each AA.) bind together with a covalent bond called a Peptide Bond . It always forms between the carboxyl group of one AA and the amino group of another. Peptide bond water is removed therefore a dehydration synthesis reaction. 2 AA = dipeptide, 3 AA = tripeptide, 10-100 AA = Polypeptide 100+ AA = protein Ex: Hemoglobin has 4 polypeptide chains
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