Energy & Enzymes

Energy The ability to cause matter to change or do work. 2 forms 1. Potential- energy stored in object 2. Kinetic- energy of motion or work

Chemical reactions Absorb and release energy by breaking or forming chemical bonds.

Parts of a reaction Reactants- substances being combined or broken apart during chemical reaction Products- the new substances being formed during a chemical reactions Ex- 6CO 2 + 6H 2 O + light  C 6 H 12 O 6 +6O 2 – Reactantsproducts

Types of reactions Exergonic reactions- release energy aka catabolic(ex-cellular respiration) Endergonic reactions- absorb energy aka anabolic (ex- photosynthesis)

Starting chemical reactions (requires lots of energy) Activation energy- the energy needed to start a chemical reaction Catalyst- a substance that speeds up a reaction by lowering the activation energy without being used itself ex- enzymes graphs

Using a catalyst decreases the amount of energy and time needed for the reaction to occur.

Enzymes A protein used by cells to start a chemical reaction, but is not destroyed by the reaction. Without enzymes our bodies could not provide enough energy to fuel the reactions in our body such as digestion.

Common uses/importance of enzymes 1. Digestion 2. Start other chemical reactions in your body such as DNA replication, making ATP, breaking down waste in cells 2. Detergents, stain removers 3. Pasteurizing milk 4. Contact lens cleaner 5. Break down sewage 6. Helps make glue and other binding agents

How do enzymes work? Like a Lock & Key 1. The enzyme binds to a reactant in a chemical reaction called the substrate. 2. The part of the enzyme where the substrate binds is called the active site.

3. The enzyme lowers the activation energy of the reaction and the reaction occurs.

Only certain active sites fit certain substrates. (like a lock and key)

Induced- fit model The lock and key model of enzyme function is an older model and does not work for all enzymes Induced fit is a more accurate model of enzyme action based on more current research and adds to the lock and key model This model is more consistent with a wider range of enzyme behavior

Induced fit continued A change in the shape of an enzyme’s active site, induced (caused) by the substrate the shapes of the enzyme, active site, and substrate adjust to maximize the fit, which improves efficiency.

Enzymes will start reactions in a variety of ways A. active site orients substrates in correct position for a reaction B. enzyme brings substrates closer together C. active site binds to substrate & puts stress on bonds that must be broken, making it easier to separate molecules

SiteEnzyme nameRole MouthSalivary amylase Breaks down starches StomachPepsinBreaks down proteins Small intestineTrypsinBreaks down proteins Small intestineLipaseBreaks down fat Small intestineMaltase, lactase, sucrase Breaks down sugars

Factors that affect enzyme activity: 1. pH 2. Temperature If either are too high or too low it will destroy or denature the enzyme 3. feedback inhibition- stopping a chemical reaction because there is enough product

Enzyme shape- definite three dimensional shape that allows binding to a substrate.