C-Notes: Enzymes Stnd: BI.1b 9/9/13 Objective: SWBAT recognize that enzymes are proteins that catalyze biochemical reactions in cells.
What are Enzymes? “Helper” protein molecules Are PROTEINS that acts as biological catalyst to speed up chemical reaction in living cells. (“catalyst/catalyze/catalase” the action of enzymes to speed up a chemical reaction in living cells)
Flow of energy through life Life is built on chemical reactions
How do Enzymes function (work) in a cell ? 1.Building molecules 2. Breaking down molecules They do almost ALL the work within a cell. **It decreased activation energy and increase reaction rate. ** enzyme + + We can ’ t live without enzymes!
How does the structure of an enzyme affect its function? 1.Enzymes are SPECIFIC! Each enzyme has a SPECIFIC “SHAPE” that only allows for a certain “reactant” to bind to it. (needs to be the RIGHT SHAPE for the job) 2. Enzymes are REUSABLE! B/C they are not used up or changed by the reaction when breaking down a substrate and can perform the same action over and over very quickly. The specific reactant that enzymes binds to is called SUBSTRATE (food & waste). Substrates binds to specific places on an enzyme called “active sites” Ex: Protease (Enzymes) only breaks down (binds to) proteins (substrate) to form amino acids “product” Ex: “protease” + “protein” Amino Acids (Enzyme) (substrate) (product) You can recognize enzymes b/c it ends in –ase Enzymes are named for the reaction the help! Ex: Lactase breakdown lactose in milk Protease breakdown proteins Lipase breakdown lipids (Enzymes) (Macromolecules)
Other terms you need to know Substrate – the substance that the enzyme works on – e.g. Lipase the substrate is lipids Product – the substance that is made by the reaction – e.g. Breakdown of Lipids by Lipase the product is __________________ – Fatty acids & glycerol
What are the Two Types of “Active Sites” (shape) model? 1.Lock & Key model (shape specific) – Substrate & enzyme fit together PERFECTLY. 2.Induced-Fit Model – Enzyme itself changes shape by Stretching and bending to fit the “substrate”.
Model of Lock and Key products substrate enzyme enzyme – unchanged active site enzyme substrate complex
What are the factors that affects enzymes activity (rate of reaction)? 1.Correct protein structure 2.Temperature 3.pH (acids and bases) level 4.Concentration of enzyme and substrate
DNA chain of amino acids folded protein right shape! wrong shape! Wrong order wrong shape cant do its job 1. How does the order of amino acid (Protein structure) affect enzyme reaction (activity)?
Ideal temperature (WORKS BEST) 35°- 40°C (body temp = 37°C) greater numbers of collisions between enzyme & substrate Raised temperature (Hot) denature protein unfold loses its shape Lowered temperature molecules move slower fewer numbers of collisions between enzyme & substrate 2. How does the Temperatur e affect enzyme reaction?
37° Temperature temperature reaction rate What’s happening here?! human enzymes
Affects on rates of enzyme reaction (activity) **changes in “pH level” changes protein “shape”** most human enzymes pH 6-8 (depends on where in body) Ex: pepsin (stomach) = pH 3 trypsin (small intestines) = pH 8 **Extremes in acid and base (pH level) will unravel or denature the enzyme** ** Each enzyme has an ideal temperature and pH** 3. How does the pH level (acids & bases) affect enzyme reaction?
The pH Scale The pH scale measures whether a solution is acid, basic or neutral. The scale runs from 0 to 14. A pH of 7 indicates that the solution is neutral. – This means that the solution is neither an acid nor a base.
4. How does concentrati on of enzymes and substrate affects enzymes reactions? – Increase “substrate” will slowdown the reaction rate – Increase “enzyme” will not speed up the rate of reaction **How fast a chemical reaction take places, depends on how much of the substrate & enzymes is available**
What are the structures of proteins? Proteins are made of chains of AMINO ACIDS. There are only 20 amino acids and can be combined in nearly countless ways. The sequence of amino acids determines the shape of the protein. The shape of the protein is the biggest factor that determines its function. There are 4 levels of structure – Primary structure Linear shape (straight line) – Secondary structure (2 types) Folding of protein structure – -helix (spiral shape) and -sheets (folded shape) – Tertiary structure actual 3D shape – Quaternary structure When 2 or more smaller polypeptides w/ different shapes join together. Any alteration in the structure or sequencing changes the shape and function of the protein
LE 5-20e Chains Chains Hemoglobin Iron Heme Collagen Polypeptide chain Polypeptide chain
What happens when enzymes (proteins) Denature? Because proteins shape are affected by temperature and pH changes. It loses its normal shape when it is not in ideal optimal environmental conditions. When a protein loses its normal shape, this is called denaturing. A denatured protein is biologically INACTIVE. – Denaturing is usually permanent and not reversible.