Proteins Making Chemical Reactions Possible Enzymes Proteins Making Chemical Reactions Possible

11/30/15 Do Now: Copy down Vocab Enzyme=special proteins that speed up chemical reactions Substrate = molecules that enzymes bind to Active site = area where chemical reactions occur Anabolism = the building up of molecules Catabolism = the breaking down of molecules Denatured = the change of shape of an enzyme due to temperature or pH Inhibitors = molecules that slow down or stop enzymes

Amoeba Sisters Video Fill out worksheet that goes along with video Biomolecules review https://youtu.be/IJ7xOSCEmZw Enzymes https://youtu.be/XUn64HY5bug

Energy and chemical reactions Most chemical reactions require energy to begin - the energy required to start a chemical reaction is called activation energy.

What are enzymes? Enzymes are proteins which reduce activation energy allowing chemical reactions to occur in living things

Enzymes reduce activation energy

Enzymes Act as Biological Catalysts Catalysts are inorganic molecules that speed up chemical reactions - Enzymes are organic molecules that speed up reactions in living things -enzymes are not changed by the reaction they speed up

Active Site Enzymes have an area called an active site. - the active site is where the chemical reaction occurs

The Shape of the Enzyme Determines Function The active site of the enzyme fits with only one type of molecule known as the substrate. Substrate is the molecule that the enzyme acts on.

Enzyme Reactions Catalase + 2H2O2 ES Catalase + 2H2O + O2 Written as : Enzyme + Substrate Enzyme + Product Example Catalase + 2H2O2 ES Catalase + 2H2O + O2 enzyme substrate enzyme product enzyme-substrate complex

Lock & Key Model Substrate fits into the active site like a key into a lock The enzyme reduces the amount of energy needed to break apart the substrate The products of the reaction leave and make the enzyme available for more substrates

Enzymes can build molecules Substrate molecules can only bond one way. Substrate molecules fit into the active site in the best position to bond Once in the active site, the molecules of substrate join together form a new product

Enzyme Inhibitors Inhibitors control the rate of enzyme activity - if there is too much of an enzyme’s product, inhibitors can slow or even stop an enzyme’s activity Two types of Inhibition - Competitive - Non competitive

Competitive Inhibition The inhibitor is a molecule that can occupy part of the active site While the inhibitor is in the active site, substrate can’t bind with the enzyme – inhibitors compete with the substrate for the active site inhibitor competes inhibitor blocks the with substrate active site

Noncompetitive Inhibition The inhibitor binds with the enzyme at a site away from the active site. Inhibitor causes enzyme to change shape – prevents substrate from entering the active site Inhibitor binds with enzyme Enzyme changes shape keeps substrate from active site

Denatured Enzymes Enzymes are proteins and if they are exposed to extremes of temp or pH lose their shape - if a protein loses its shape, it loses its function - a protein that loses its shape is said to be denatured - if an enzyme is denatured, substrate can’t enter the active site extreme temperature or pH

Common Enzymes Amylase - breaks down starch Catalase – breaks down H2O2 DNA polymerase – joins DNA nucleotides to build DNA Lipase – break apart fats Lactase – breaks apart lactose – milk sugar Protease- breaks apart protein molecules -What does –ase in a molecules’ name imply?