BIOA1H3 F - Module 3: Lecture 04
Chemical Reactions and Enzymes
Topics Review
Q: The reactions in the pathways of glycolysis and the citric acid cycle break down glucose into smaller molecules. Therefore, these pathways are?
A: Catabolic pathways → the breakdown of molecules into smaller units
Lecture Question
Q: Why are some mushrooms toxic to human beings? The example used is; Amanita phalloides
A: Amanita phalloides contains Amatoxins which are selective inhibitors of RNA Polymerase II, which is a vital enzyme in the synthesis of mRNA, microRNA, and snRNA
Core Concepts
Chemical Reactions involve the breaking and forming of bonds
Energetic Coupling: spontaneous reactions drive a non-spontaneous reaction
Enzymes: protein catalysts that can increase the rate of biochemical reactions
Allosteric Enzyme: an enzyme that is activated or inhibited when binding to another molecule changes its shape
Chemicals Reactions
involve the breaking and forming of chemical bonds
atoms keep their identity and integrity but the bonds are what are altered
hydrogen-oxygen bonds are the ones that normally break
carbon dioxide + water → carbonic acid
Free Radicals (Reactive Oxygen Species)
atoms or molecules that contain unpaired electrons making them highly reactive and unstable
will pick up electrons from the cells within the body
causes damage to cells and tissues
Antioxidants → provide electrons and serve as a reducing agent and limit the oxidative damage to cells and molecules; Selenium is a popular one
Prof’s Lab Investigation
have been investigating Selenoprotein translation
Gibbs Free Energy
Endergonic Reaction (+): if the products have more free energy than the reactant → these reactions are non-spontaneous and anabolic
Exergonic Reaction (-): if the reactants have more free energy than the products → this reaction is spontaneous and catabolic
Energy Available
Total energy or enthalpy (H) = energy available to do work + energy lost to entropy (disorder)
ΔG = ΔH - TΔS
ΔG = total Gibbs Free Energy
ΔH = total Enthalpy Change
T = Temperature in Kalvin
ΔS = total Entropy Change
ΔG in Anabolic and Catabolic Reactions
G and H are inversely proportionate to T and S
Energetic Coupling
a process in which spontaneous reactions drive a non-spontaneous reaction
Example; the coupled reaction proceeds since ΔG is negative and Pi is shared between the two reactions
Intermediate ΔG
whether ATP will be produced or consumed is dependent on the intermediate ΔG
allows ATP to drive reactions as well as be replenished
Rate of A Reaction
as a new compound is forming, a Transition State briefly occurs
it has a high energy compared to all other states and is unstable
the reaction requires an input of energy to reach this state = Activation Energy
depending on where the reaction is high or low, it may need a greater or smaller amount of energy input to reach the transition state
Enzyme-Catalyzed Reactions
Substrate ←→ Product
S + Enzyme ← → ES ← → EP ← → E + P
help speed up the chemical reactions in the body
they are proteins (normally end in ‘-ase’)
enzymes possess an active site that a substrate binds to and converts it to the product
the interactions between the substate and the active site are weak noncovalent interactions or transient covalent bonds that stabilize the transition state and decrease the activation energy required for the reaction
Active Site Formation
extremely small compared to the enzyme itself
the amino acids that compose the active site are often far apart in the linear sequence of the unfolded enzyme
protein folding brings specific amino acids close to each other to form the active site
Enzyme Specificity
partial due to the structure of the active site
is the basis of Bio-element Transducers
Activators & Inhibitors
Activators: can increase enzyme activity
Inhibitors: can decrease or inhibit enzyme activity
can be reversible or irreversible depending on how tightly they are bound to the enzyme by their bonds (ionic or covalent)
can also bind to a site that’s not the active site - these sort of inhibitors will change the shape of the enzymes active site so then the enzyme itself cannot recognize the substrate anymore
can also be classified on how they inhibit or bind with enzymes
they can compete with the substrates
Regulation of Chemical Reactions
allosteric enzymes are important in the regulation of chemical reactions
Chemical Reactions and Enzymes
Topics Review
Q: The reactions in the pathways of glycolysis and the citric acid cycle break down glucose into smaller molecules. Therefore, these pathways are?
A: Catabolic pathways → the breakdown of molecules into smaller units
Lecture Question
Q: Why are some mushrooms toxic to human beings? The example used is; Amanita phalloides
A: Amanita phalloides contains Amatoxins which are selective inhibitors of RNA Polymerase II, which is a vital enzyme in the synthesis of mRNA, microRNA, and snRNA
Core Concepts
Chemical Reactions involve the breaking and forming of bonds
Energetic Coupling: spontaneous reactions drive a non-spontaneous reaction
Enzymes: protein catalysts that can increase the rate of biochemical reactions
Allosteric Enzyme: an enzyme that is activated or inhibited when binding to another molecule changes its shape
Chemicals Reactions
involve the breaking and forming of chemical bonds
atoms keep their identity and integrity but the bonds are what are altered
hydrogen-oxygen bonds are the ones that normally break
carbon dioxide + water → carbonic acid
Free Radicals (Reactive Oxygen Species)
atoms or molecules that contain unpaired electrons making them highly reactive and unstable
will pick up electrons from the cells within the body
causes damage to cells and tissues
Antioxidants → provide electrons and serve as a reducing agent and limit the oxidative damage to cells and molecules; Selenium is a popular one
Prof’s Lab Investigation
have been investigating Selenoprotein translation
Gibbs Free Energy
Endergonic Reaction (+): if the products have more free energy than the reactant → these reactions are non-spontaneous and anabolic
Exergonic Reaction (-): if the reactants have more free energy than the products → this reaction is spontaneous and catabolic
Energy Available
Total energy or enthalpy (H) = energy available to do work + energy lost to entropy (disorder)
ΔG = ΔH - TΔS
ΔG = total Gibbs Free Energy
ΔH = total Enthalpy Change
T = Temperature in Kalvin
ΔS = total Entropy Change
ΔG in Anabolic and Catabolic Reactions
G and H are inversely proportionate to T and S
Energetic Coupling
a process in which spontaneous reactions drive a non-spontaneous reaction
Example; the coupled reaction proceeds since ΔG is negative and Pi is shared between the two reactions
Intermediate ΔG
whether ATP will be produced or consumed is dependent on the intermediate ΔG
allows ATP to drive reactions as well as be replenished
Rate of A Reaction
as a new compound is forming, a Transition State briefly occurs
it has a high energy compared to all other states and is unstable
the reaction requires an input of energy to reach this state = Activation Energy
depending on where the reaction is high or low, it may need a greater or smaller amount of energy input to reach the transition state
Enzyme-Catalyzed Reactions
Substrate ←→ Product
S + Enzyme ← → ES ← → EP ← → E + P
help speed up the chemical reactions in the body
they are proteins (normally end in ‘-ase’)
enzymes possess an active site that a substrate binds to and converts it to the product
the interactions between the substate and the active site are weak noncovalent interactions or transient covalent bonds that stabilize the transition state and decrease the activation energy required for the reaction
Active Site Formation
extremely small compared to the enzyme itself
the amino acids that compose the active site are often far apart in the linear sequence of the unfolded enzyme
protein folding brings specific amino acids close to each other to form the active site
Enzyme Specificity
partial due to the structure of the active site
is the basis of Bio-element Transducers
Activators & Inhibitors
Activators: can increase enzyme activity
Inhibitors: can decrease or inhibit enzyme activity
can be reversible or irreversible depending on how tightly they are bound to the enzyme by their bonds (ionic or covalent)
can also bind to a site that’s not the active site - these sort of inhibitors will change the shape of the enzymes active site so then the enzyme itself cannot recognize the substrate anymore
can also be classified on how they inhibit or bind with enzymes
they can compete with the substrates
Regulation of Chemical Reactions
allosteric enzymes are important in the regulation of chemical reactions
