1. Energy & Enzymes
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2. Objectives
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3. Vocabulary Metabolism Catabolism Anabolism
The totality of an organism’s chemical processes, consisting of catabolic and anabolic pathways
Catabolism
Release of energy by breaking down complex molecules into simpler molecules.
Anabolism
Involves putting things together or synthesizing complex substances from simpler substances
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4. Enzymes Enzymes are responsible for lowering the activation energy
Enzymes are responsible for speeding up chemical reactions in the body
Chemical Reactions
Reactants
When using enzymes, the reactants are called substrates
Products
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6. Amino Acids & Enantiomers
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9. Monomers vs. Polymers Monomers are the precursors to polymers
A polymer CANNOT be made without monomers
Question?
What is the process used to join multiple monomers together so that a polymer is produced?
Polymerization
In order to make proteins (enzymes) multiple amino acids must be joined together
Hence, that means that the amino acid is the monomer.
Amino Acid-->peptide-->polypeptide-->protein
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13. Enzymes Structure of Enzymes Protein molecules
Some enzymes are known to contain non-protein components
These are known as coenzymes
Vitamins frequently function as coenzymes
Enzymes are very specific
Substrate
Maltose—Maltase
Amylose—Amylase
Lipid—Lipase
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15. Exergonic Reaction
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16. Activation Energy
The difference in energy between the energy for the reactants and the transition state.
ALL chemical reactions must overcome the transition state.
The transition state represents a hump in the road.
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17. Exergonic Reaction
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18. Exergonic Reaction A reaction that occurs spontaneously
The product of an exergonic reaction has a lower energy level than that of the reactants
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19. Activation Energy Activation Energy Transition State
The energy difference between reactants and the transition state
Determines how rapidly the reaction occurs at a given temperature
The lower the activation energy, the faster the reaction will occur
The higher the activation energy, the slower the reaction will occur
Transition State
Represents the highest-energy structure involved in the process of a chemical reaction
A chemical reaction must have enough energy to overcome the “transition state.”
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20. Enzymes
Active sites
Specific site on the enzyme where the substrate attaches
Pocket; Lock
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21. How do Enzymes Work? Catalytic Cycle
Four Steps
Enzyme and substrate are available
Substrate binds to enzyme (enzyme-substrate complex)
Substrate is converted to products
Products are released
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23. Influences on Enzymes Temperature
Extreme cold can slow enzyme action nearly to a halt
As temperature rises, enzymes begin to operate more and more rapidly
Extreme heat can halt enzyme action by changing the enzyme’s shape—denaturation
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24. Influences II Concentrations of Enzyme to Substrate
If the concentration of an enzyme is constant, increasing the substrate concentration from zero will result in a steady rise in the reaction rate until there are equal amounts of substrate and enzyme
Rate of product production increase, but eventually it will level off.
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25. Influences III Cell Acidity (pH)
Most enzymes appear to work best at a pH of 7
Remember the approximate pH of blood?
Rates will decrease with more acidity or alkalinity
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28. Enzymes--Inhibitors Enzyme Inhibitors Non Competitive Inhibitors
Resemble the substrate molecule for that specific enzyme
Competes for the active site
Reduces the productivity of enzymes by blocking
Non Competitive Inhibitors
Do not directly bond to the active site of the enzyme
Binds at another location and alters the confirmation of the enzyme so that the active site is no longer fully functional
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31. Control of Metabolism Depends on allosteric regulation
Changes an enzymes shape and function by binding to an allosteric site
Specific receptor site on some part of the enzyme molecule remote from the active site
Allosteric inhibitor, binds at the allosteric site, and stabilizes the inactive form of the enzyme
Makes the enzyme non-functional
Activator, also binds at the allosteric site, and stabilizes the active form on the enzyme
Makes the enzyme functional
ATP and ADP are examples
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32. Allosteric Regulation
Active Form
Activator binds at the allosteric site
Enzyme becomes active
Substrate is able to bind at active site and the chemical reactions (conversion to products) can take place
Inactive form
Inhibitor binds at the allosteric site
Enzyme changes shape
Enzyme becomes inactive
Substrate is unable to bind at the active site
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34. Control of Metabolism II
Feedback Inhibition
The switching off a metabolic pathway by it’s end product
The end product switches off the metabolic pathway
Example of Baking a cake
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36. Start point
Theronine
End Point
Isoleucine
If the body has enough isoleucine, isoleucine will bind at the allosteric site of the last enzyme
Isoleucine, when binding at the allosteric site will behave as an allosteric inhibitor
This turns the enzyme off
The pathway turned off
If the body uses all of the isoleucine, then isoleucine leaves the last enzyme and an allosteric activator binds and turns the enzyme on
When the enzyme is turned on, the pathway is turned on
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37. Cooperativity Amplifies the response of enzymes to substrates
The binding of one substrate molecule to the active site of one subunit causes all the subunits to assume their active form
December 9, 2018