Presentation on theme: "MACROMOLECULES PROTEIN PROTEINS Probably the most diverse group of macromolecules is the proteins."— Presentation transcript:
PROTEINS Probably the most diverse group of macromolecules is the proteins.
PROTEINS Proteins are complex polymers composed of C, H, O and N. Polymer : large molecule formed when many smaller molecules bond together
FUNCTIONS OF PROTEINS Serve as structural components of animals, build and repair body tissue. Maintain cell growth Serve as control molecules (enzymes) Serve as transport and messenger molecules Provide as energy if sufficient carbohydrates and fats are not supplied by the diet. Ex. Keratin, elastin, collagen
PROTEINS The building blocks of proteins are smaller molecules called amino acids held together by peptide bonds Most end in ine Despite the wide variety of life on Earth, all living organisms use only 20 different amino acids to produce the proteins they require
PROTEINS Green plants can make all 20 essential amino acids on their own; animals cannot. Thus, animals, including humans, must get some of these essential amino acids from the foods they eat.
All animal proteins are complete proteins: i.e. milk, eggs, cheese, fish and meat have all 9 amino acids. Proteins from some plant sources, such as brewer's yeast, certain nuts, soybeans (tofu is made from soybeans), cottonseed, and the germ of grains are also complete proteins. Partially complete proteins do not contain all 9 of the essential amino acids but a limited amount of one or more of them. Partially complete amino acids provide normal maintenance but will not support growth.
PROTEINS Enzymes are important proteins found in living things. An enzyme changes the rate of a chemical reaction. Enzymes are involved in nearly all metabolic reactions Usually end in ase
PROTEINS Substrate- Component in an enzyme reaction Enzyme reactions take place in the active site Substrate + Enzyme Product + Enzyme The enzyme is unchanged in the reaction.
PROTEINS Each enzyme is specific to only one reaction. This reaction is often compared to a lock and key.