MACROMOLECULES

PROTEI N

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.