In this IBDP Biology Blog post, we will learn:
- What metabolic pathways are
- What is the Activation energy
- What is competitive and non-competitive inhibitors?
METABOLIC PATHWAYS & ACTIVATION ENERGY
U1: Metabolic pathways consist of chains and cycles of enzyme-catalyzed reactions
Metabolic Pathways: Cycles or Chains of enzyme-catalyzed reactions
U2: Enzymes lower the activation energy of the chemical reactions they catalyze
Activation Energy: The initial input of energy that is required to trigger a chemical reaction
How do enzymes lower the Activation Energy of a Reaction?
- Substrate binds to Active Site and
Active Site is altered to reach the trasition state
- Due to the binding bonds in the substrate become stressed/less stable
- The binding lowers the overall energy level of the transition state
- Therefore the
Activation Energy of the Reaction is reduced
COMPETITIVE VS NON-COMPETITIVE INHIBITION
Inhibitor: A molecule that binds to an enzyme and slows down or stops the enzyme's function
Good: Ensures reaction does not proceed too fast
Bad: Undesirable
COMPETITIVE & NON-COMPETITIVE INHIBITORS
Competitive Inhibitors
- Has a similar structure to the Substrate
- Temporarily binds to the Active site
- The higher the concentration of the inhibitor is the slower the rate of reaction
- Succinate binds to Succinate Dehydrogenase to produce Fumurate
- The Inhibitor and Substrate both compete for the Active Site
- If the Substrate binds to the Active Site the Inhibitor cannot and vice versa
- As substrate concentration rises a Substrate is more likely to bind to a vacant Active Site than an Inhibitor
- At very high Substrate concentrations and low Inhibitor concentrations the Substrate almost always wins the competition and binds to the Active Site so the Enzymatic Rate is almost as high as when there is no Inhibitor
Competitive Inhibitor: Malonate
Non-Competitve Inhibitors
- Does not necessarily have the same structure as the Substrate
- It binds to the enzyme at the Allosteric Site - changing the shape of the Active Site therefore decreasing the rate of the reaction and preventing the Substrate from binding
- The Substrate and Inhibitor are not competing for the Active Site because the Inhibitor binds to the Allosteric Site on the enzyme
- The Substrate cannot prevent the binding of the Inhibitor even at high Substrate Concentrations
- The same number of enzymes molecules are inhibited at the same number of substrate concentrations
- Even at high substrate concentrations the Enzymatic Rate is lower than then there is no Inhibitors
Non-Competitive Inhibitor: Morphine
That's it for this topic!
Drafted by Venetia (Biology)
References:
- https://www.google.com/url?sa=i&url=https%3A%2F%2Fcourses.lumenlearning.com%2Fsanjacinto-biology1%2Fchapter%2Fenzymes%2F&psig=AOvVaw2OZi2yB9ZWOTZUAhF7jhxN&ust=1625735993763000&source=images&cd=vfe&ved=0CAoQjRxqFwoTCLDvjtbQ0PECFQAAAAAdAAAAABAF
- https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.khanacademy.org%2Fscience%2Fap-biology%2Fcellular-energetics%2Fenvironmental-impacts-on-enzyme-function%2Fa%2Fenzyme-regulation&psig=AOvVaw2ssfA5mCOFomBFweW5GPoe&ust=1625736619325000&source=images&cd=vfe&ved=0CAoQjRxqFwoTCJCKuYHT0PECFQAAAAAdAAAAABAD