Metabolism: Energy and Enzymes. Chapter 6. Energy = the ability to do work. Kinetic Energy (energy of motion) Potential Energy (stored energy). First Law of Thermodynamics - the law of conservation of energy
Kinetic Energy (energy of motion)
Potential Energy (stored energy)
First Law of Thermodynamics - the law of conservation of energy
Second Law of Thermodynamics - energy cannot be changed without a loss of usable energy (heat)
Functions:1. CHEMICAL WORK - Supplies energy needed to make macromolecules that make up the cell (and organism)2. TRANSPORT WORK - Supplies energy needed to pump substances across the cell membrane3. MECHANICAL WORK - supplies energy needed to make muscles contract and other cellular parts to move (flagella)
Enzyme - protein molecule that functions as an organic catalyst to speed reactions
Substrate - reactants in the enzymatic reaction, this is what an enzyme attaches to
Energy of Activation - the energy required to cause the reaction
1. Substrate concentration2. Temperature & pH *3. Enzyme concentration
Enzymes can be denatured - they change shape so much that they are no longer effective. High temp or pH can cause denaturation.
Siamese cats have an enzyme that works at lower temperatures only, causing the nose and ears to become a darker color than the rest of the body.
Enzymatic Inhibition - when a substance binds to an enzyme and decreases its activity. (Usually reversible)
Noncompetitive Inhibition (allosteric site)
**Both are forms of feedback inhibition
QUESTION: What type of inhibition is pictured below?
2H2O2 ----> 2H2O + O2
Hydrogen Peroxide is broken down by the enzyme: catalase within cells.
KMNO4 (potassium permanganate) can be used to determine how much H2O2 is left within the flask after the reaction has stopped. (Titration)
You slowly add KMnO4, which is purple, to the flask. The peroxide in the flask causes the KMnO4 to lose color when the solution is mixed thoroughly. When all the peroxide has reacted with KMnO4, any additional KMnO4 will remain light brown or pinkish even after you swirl the mixture. This is the endpoint. Record the amount of KMnO4 you have used.
The more KMnO4 you use, the more peroxide is left in the flask.
Generally speaking, catalase reactions occur faster at warmer temperatures.
If temperature is too hot (boiling) then the enzyme becomes denatured
McGraw Hill Lab
Bio 114 Enzymes
Lab Bench Enzyme Catalysis