CHAPTER 2 NOTES
Function: build structural materials and carry out cell metabolism.
· Act as hormones, enzymes or carrying molecules.
· Help transport substances into/out of a cell.
· Help fight disease.
· Make up keratin (nails), collagen (connective tissue) and muscle.
· made out of C, H, O and N (sometimes S)
Proteins are long polymers of monomers called amino acids.
· proteins are sometimes called polypeptides.
· defined as the building blocks of proteins.
· joined together by a covalent bond called a peptide bond.
· there are 20 different amino acids make up all of the proteins.
· 13 of the amino acids are essential.
Structure of an amino acid:
1. amine group (-NH2)
2. carboxyl group (-COOH)
3. R-group (differs for the 20 different amino acids)
R-groups can be acidic or basic, polar or nonpolar. Some contain carbon rings.
Proteins have four levels of organization:
1. the sequence of amino acids.
2. amino acids within a chain can be twisted or folded.
3. the chain itself can be folded resulting in a 3-dimensional shape.
4. specific folded protein chains (shapes) fit together like puzzle pieces.
Proteins can be denatured (they lose their 3-D shape) by high heat or strong acids and bases.
A chemical reaction is a process that changes one set of chemicals (the reactants) into another set of chemicals (the products.)
· Whenever chemical bonds are broken, energy is released. Sometimes occurs spontaneously and other times needs a boost of energy.
· Whenever new chemical bonds are made, energy is absorbed and stored. Usually requires a boost from a source of energy.
· The activation energy (Ea) is the energy need to get a reaction started.
Enzymes also provide a site where reactants can be brought together to react.
Substrate: the reactants of enzyme-catalyzed reactions.
Active site: an area of the enzyme that fits like a lock and key with the substrate (very specific). The active site and the substrate have complementary shapes.
Draw a picture:
Label enzyme, substrate, active site, enzyme-substrate complex and products.