7.3 Flashcards
Enzymes are biological catalysts
-Many proteins and some RNA molecules act as enzymes
-enzyme shape stabilizes transient association between substrates
-Enzyme not changed or consumed in reaction ( can function over and over again)
- different cell types contain different enzymes
-enzymes may be soluble or associated with membranes
Active site
-A pocket for substrate binding
-Allows precise fit of substrate
-applies stress to distort bonds to lower activation energy
-induced fit
Induced fit
Enzymes may change shape to maximize contact with substrate
Factors that influence enzyme function
-Concentration of substrate
-Concentration of enzyme
-Any chemical or physical condition that affects the enzymes structure
*temp, pH, regulatory molecules (inhibitors)
Enzyme regulatory molecules
-Allow cells to control enzyme ( for allosteric enzymes)
-Inhibitor
-some regulator molecules are enzyme active
Inhibitor
molecule that binds to and decreases the activity of an enzyme
Competitive inhibitor
Competes with substrate for active site
Noncompetivite inhibitor
Binds to enzyme at a site( allosteric site) other than active site
Causes shape change that makes enzymes unable to bind to substrate
Metabolism
Total of all chemical reaction carried out by an organism
- anabolic reactions
-catabolic reactions
Anabolic reactions (anabolism)
Expend energy to synthesize molecules
ex: amino acids/ fatty acids
Catabolic reactions (catabolism)
Harvest energy by the breakdown of molecules
Ex: carbs or lipids
Biochemical pathways
-reactions occur in a sequence
- product of one reaction is the substrate for the next reaction
-many occur within organelle or within certain membrane
Feedback inhibition
-end product of pathway binds allosteric site on first enzyme in pathway
-shuts off pathway so raw materials and energy are not wasted
