Week 2

Enzymes and Energy

learning goal: Appreciate how the laws of thermodynamics relate to the function of cells and how

enzymes modulate the rate of chemical reaction to regulate cellular processes.


cells needs to be able to acquire, transform, and use enrgy to power up cellular processes


metabolism in cells: refers to all the chemical reactions happening in a cell


chemical reactions in cells: involve either the forming or breaking of chemical bonds


arrows will provide insight on the type of chemical reaction that is happening




all chemical reactions will involve energy that is being transformed

  • this will allow us to understand the conditions that need to be met in order for the reaction to occur in the first place



energy definition": is defined as the capacity to do work

  • there are different forms of energy

  • thermal (heat)

  • chemical

  • radiant light energy

  • mechanical energy


work definitioN: work in biology can be defined as the the ability to move or change things, the ability to do something



interpretting the signs to see if energy is going to be released or required for the reaction to proceed

  • If the delta g standard sign is negative → then the reaction is losing energy/ energy released to its environment

    • this means that the reaction is exergonic

  • IF the delta g sign is postive then the reaction is going to require energy

    • this means that the reaction is endergonic



Gibbs Free Energy Equation

  • the triangle symbol is going to indicate that there is change in something (final state-initial state)

  • delta h is refereding to the change in enthalpy   

    • the change in the potential energy of bonds

    • will help us understand the strength of the bonds that we are breaking or forming

  • t is refering to temperature in units kelvin

  • delta s is referring the change in entropy

    • the change in the disorder of a system


what is enthalpy

  • referrring to the potential energy that is associated is bonds


  • when bonds are at a higher potential energy → the system is going to be less stable

    • this able this as a relationship, when you meet someone the potential you have with that person is going to be higher…

    • when a system has lower potential energy the system is more stable


provide an example where we are counting the total potential energy from each component in the products and reactants to find the delta h value


realtive energy/stability


understanding entropy

  • higher disorder = higher entropy

  • systems will naturally tend to be more disordered since it requires more energy to keep a space maintained


Free Energy and Metabolic Pathways

  • anabolic pathways are endergonic

    • anabolic pathways will transfer energy from atp to build complex molecules and will rele

  • catabolic pathways will be exergonic and release energy


When we form bonds we are released heat

When we breaks bonds we are requiring heat


entropy decreases in anaboic reactions

when the delta s value is negative the reaction will become more endergonic, there is going to be a larger energy input required


atp hydrolysis is referring to the use of atp




we are able to manipulate the delta g value by changing the conditions of the reaction such as


if we are given just the delta g value, we are unable to tell the rate at which a reaction is occurring at, it will just provide us information regarding the change in free energy in the system and will tell us whether a reaction will require or release energy


activation energy

  • this is what is going to determine the rate of a reaction

  • if something has large activation energy the reaction is going to occur slowly since the energy barrier is going to be higher to reach and harder to overcome

  • if something has lower activation energy then the energy needed for the reaction to occur is lower and the reaction is going to occur more quickly


Enzymes

  • are a type of protein

  • they will help with catalyzing chemical reactions

  • they can help with coupled reactions

  • can help in speeding or slowing down reactions

  • can work in forward and reversible reactions

  • functions by forming noncovalent interaction with the substrate (find the defintiion for this term) and allows it to go to a lower transitions state to require less energy


  • the activation site for an enzyme is important and altering this shape can change the function

  • an enzyme will have optimal temperature and pH conditions that it will function in



  • defining what pH is

    • a measure of protion (h+) concentration

    • if pH value is lower that will indicate higher h+ concentration

    • a higher pH value will indicate lower h+ concentration


regulation of enzymatic activity happens through a feedback chain of inhibition and activaition