Enzymes and Reactions Flashcards
Metabolism
All chemical reactions in an organism
Necessary for obtaining the energy for all other aspects of life
Catabolic
Reactions that break down complex molecules
Anabolic
Reactions that build up complex molecules
Describe the
Energy of Metabolic Reactions
Catabolic - breaks down molecules and releases energy; exergonic
Anabolic - builds up molecules and requires the input of energy; endergonic
Define
Energy
Capacity to cause change
Ability to do work
Ability to move matter
Two categories of energy
Kinetic and Potential
Define
Kinetic Energy
Energy of moving objects
Define
Potential Energy
Energy of position, which can transform to kinetic energy
Chemical Energy
Potential energy related to the chemical bonds of compounds
First Law of Thermodynamics
Energy cannot be created or destroyed
Second Law of Thermodynamics
Entropy increases every time energy is transferred or transformed
Define
Entropy
Disorder / randomness
Constantly increases
Exergonic
Reactions where the reactants have more potential energy than the products
Energy is released
Endergonic
Reactions where the products have more potential energy than the reactants
Energy must be absorbed
What can you determine about this reaction?
What can you determine about this reaction?
Stability, energy, and entropy
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Simplest molecules have the least potential energy, most entropy, and are the most stable
Building molecules requires the input of energy, a decrease in entropy, and increases order
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ATP
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Adenosine tri-phosphate
Hydrolysis of ATP to ADP releases energy that can be coupled with endergonic reactions
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Describe this molecule
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Adenosine tri-phosphate
Nitrogenous base = Adenine
Ribose
Adenine and ribose makes adenosine
Three phosphate groups; the last phosphate is easily removed to release energy
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ADP
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Adenosine di-phosphate
Phosphate group can be added via dehydration reaction to make ATP to “store” energy
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Define
Enzyme
Biological catalyst
Properties of
Enzymes
Reduce activation energy
Increase the rate of chemical reactions
Specific to one reaction
Made of proteins or RNA
Activation energy
The energy required to break bonds in the reactants of a reaction
Energy needed to start a chemical reaction
Describe this graph
Black line = Reaction without an enzyme present; activation energy is energy above the dotted line
Red line = Reaction with an enzyme present
Difference between reactants and products is NOT changed!
How enzymes work
- Can allow for proper orientation of particles
- Stresses covalent bonds
- Creates a better environment for the reaction to occur
Define
Substrate
Reactant that binds to an enzyme to react
Define
Active site
Part of enzyme that binds substrate
Describe the
Induced Fit Model
The binding of the substrate to the active site causes a change in the enzyme, enabling it to work
How are enzymatic reactions affected by
Temperature
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Low temp: Low reactions due to fewer collisions
Optimal temp: Highest rate of reactions
High temp: Low enzyme activity because enzyme denatures
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How are enzymatic reactions affected by
pH
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Too acidic or too alkaline: Low enzyme activity because enzyme denatures
Optimal pH: Highest rate of reaction
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How are enzymatic reactions affected by
Enzyme concentration
Increasing enzyme increases overall rates of reactions in cells (assuming excess substrate)
How are enzymatic reactions affected by
Substrate concentration
Increasing substrate concentration increases overall rates of reactions until enzymes are saturated at which point the reaction rate will level off
How are enzymatic reactions affected by
Cofactors
Increase rate of reactions
How are enzymatic reactions affected by
Competitive inhibitors
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Decrease/stop reactions
Increasing substrate concentration can increase reaction rate
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How are enzymatic reactions affected by
Allosteric regulators
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Decrease/stop reactions
Substrate concentration does not affect reaction rate
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