METABOLISM & ENZYMES
Metabolism METABOLISM- The sum total of an organisms chemical reactions in the body (or a cell). 2 Types of Metabolic Pathways: ○ Catabolic- Release energy by breaking down complex molecules into simpler ones. ○ Anabolic- Consume energy to build up complex molecules from simpler ones.
Making Cellular Energy (ATP) ATP- Adenosine Tri-Phosphate. ATP is the cell’s “energy bank”. ATP ADP + P (energy released to do cellular work). This breaking of a phosphate bond releases and provides energy for chemical work (polymer building), transport (active transport), and mechanical work (muscle contraction). ADP + P ATP (energy provided by cellular respiration). This bonding of a phosphate group stores energy in the molecule. Extremely rapid turnover (broken down and re-made).
Enzymes AKA Organic Catalysts – Speed up a chemical reaction without being “used up” or altered in the reaction. How? By lowering the activation energy – energy required for initiation of a reaction. Enzymes are Proteins, (they have a specific shape and specific function). SUBSTRATE –The compound the enzyme works on.
Enzyme Reactions Overall reaction: E + S ES Complex E + P (Enzyme + Substrate Enzyme/Substrate Complex Enzyme + Product) Dehydration Synthesis reactions: E + S 1 + S 2 ES Complex E + P Hydrolysis reactions: E + S ES Complex E + P 1 + P 2
Enzyme Specificity Enzymes break down/build up specific substrates. Referred to as a “lock-and-key” model Location where substrate binds to enzyme is called the ACTIVE SITE. Enzymes must have a specific shape to “fit” the substrate. Typically end in the suffix “-ase”. Ex. - Lactase breaks down Lactose.
Factors Affecting Enzyme Activity Temperature: 1. • • All enzymes work under a specific temperature range. Enzymes undergo DENATURATION (loss of shape) at extreme temperatures (and p. H). p. H: 2. • • • All enzymes work under a specific range of p. H. E. x. - Pepsin and Trypsin both break down proteins in the digestive system but at different p. H’s. E. x. - Blood p. H MUST stay at 7. 4
OPTIMUM TEMPERATURE
Factors Affecting Enzyme Activity 3. Proper Amounts of Substrate/Enzyme: - Reaction will only go as quickly as there is proper amount of enzyme or substrate. - You cannot break down a set amount of substrate without a proper amount of enzyme…and vice-versa!
Regulation of Enzymes COMPETITIVE INHIBITION – Product (or another compound) competes with substrate for active sites. NON-COMPETITIVE INHIBITION – Product joins with an allosteric site which changes the shape of the active site. Allosteric Site- Any place on the enzyme other than the active site Examples: Poisons, Pesticides, Antibiotics
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