How is energy measured?
As Joules or Calories
What are the two types of energy?
1) Potential Energy - stored energy
2) Kinetic Energy - energy of motion
Define Kinetic Energy
Includes Heat Energy which is the movement of atoms;
and Light Energy which is the movement of photons
Define Potential Energy
Includes Chemical Energy which is the energy stored in chemical bonds
What is the first law of Thermodynamics?
Energy cannot be created or destroyed, only converted from one form to another or transferred from one object to another
What type of energy is used with a dam?
Potential energy - the higher the water level (with the dam closed), the more potential energy
Kinetic energy- when the water is released
What is the 2nd law of Thermodynamics?
Energy conversions are not perfect and are accompanied by increased Entropy
*All systems tend toward disorder*
- The loss of Energy to Entropy is often observed as heat
Define Entropy
The Energy that is lost from the system, and cannot be used for further work
*It is the amount of disordeer in a system*
_____ are much more random than ______
Products are much more random than reactants
How does our biological metabolism lose energy as entropy?
By giving off heat as we exercise
Also as we metabolize ______ or ______ we convert a single molecule into several molecules of ______ and _____
Also as we metabolize glucose or sucrose we convert a single molecule into several molecules of CO2 and H2O
Summary of the 1st law of Thermodynamics
Energy before ——> Energy after
(Reaction)
Summary of the 2nd law of Thermodynamics
Energy before ——-> 3/4 usable energy + 1/4 Unusable
(reaction)
Chemical reactions _______________
Chemical bonds are __________
Chemical reactions release or store energy
Chemical Bonds are Potential Energy
Some Energy is always lost as _______
Entropy
Reactants are converted to Products
C6H12O6 + 6O2 ——–> 6H2O +6CO2
how many molecules in each?
C6H12O6 + 6O2 = 7 molecules
6H2O + 6CO2 = 12 molecules
Define Exergonic
Example?
Net release of energy
The reactants contain more energy than the products
-(delta)G
EX. fire
Define Endergonic
Example?
Net storage of energy
The products contain more energy than the reactants
+(delta)G
EX. Photosynthesis
What is the formula for Gibb’s free Energy?
What do each stand for?
(delta) G= (delta)H- T(delta)S
(delta) H = change in enthalpy or heat (potential Energy)
(delta) S = change in entropy
T= temperature
What is the differene between enthalpy and entropy?
Enthalpy = the transfer of energy
Entropy = disorder = energy lost
What does gibb’s free energy allow?
Gibb’s free energy allows you to determine whether a reaction will be spontaneous, and under what conditions
So both change in ________ and change in ________ dictate whether a reaction is favourable or not
So both change in potential energy ((delta)H) and change in entropy ((delta)G) dictate whether a reaction is favourable or not
A glass of ice melts at room temperature
Ice ———-> water
Is H higher for ice or water?
Is S higher for ice or water?
H is higher for water
S is ********
Ice ——> water
(delta) H =
(delta) S =
So as long as _______ the reaction will be favoured
(delta) H is positive- it is an endothermic reation
(delta) S is negative
So as long as T(delta)S>(delta)H the reaction will be favoured
Exergonic Reactions:
The products contain more/less energy than the reactants
Examples?
The products contain less energy than the reactants
Ex. burning wood, cellular respiration
*Free energy decreases* -G
Endergonic Reactions:
The products contain more/less energy than the reactants
Examples?
The products contain more energy than the reactants
EX. dissolving table salt in water, photosynthesis
*Free energy increases* +G
Endergonic reaction:
The change in (delta)G tells us whether the reaction will occur __________
What is the formula?
The change in (delta)G tells us whether the reaction will occur without addition of outside energy
(delta)G = Gproducts - Greactants
Endergonic reaction:
A negative (delta)G value suggests the reaction is _____
favored to proceed
An ________ reaction can be coupled to a _______ reaction to make the overall reaction energetically favourable
An Endergonic reaction can be coupled to a Exergonic reaction to make the overall reaction energetically favourable
In cells, the coupled Exergonic reaction is often the ____________
Hydrolysis of ATP
ATP stands for?
ATP is used by the cell to ________
ATP = Adenosine Triphosphate
ATP is used by the cell to make unfavourable reactions occur
ATP:
Entropy ______
(delta)G is _______
Entropy increases
(delta)G is negative
ATP is converted to ADP using what?
H2O = hyrdolysis
ATP–> ADP+Pi
Exergonic reation breaking down ATP provides energy for _______________
Exergonic reation breaking down ATP provides energy for endergonic reactions in the cell
ADP + Pi —> ATP
______ reactions supply energy for endergonic reaction producing ATP
Exergonic-catabolic reactions
Biosynthesis of glutamine is an ______ reaction
What is the formula without ATP?
Endergonic reaction
Glutamine acid + Ammonia —> Glutamine
Glu + NH3 —>NH2 Glu
Wtih ATP:
ATP can be hydrolyzed to make ___________, a reactant with more/less energy.
This makes the synthesis of glutamin an ______ reaction
What is the formula?
Phospho-glutamic acid
more energy
Exergonic
1) Glu + ATP —-> Glu-P + ADP
2) Glu-P + NH3 —-> Glu NH2
Coupling glutamine synthesis with ATP hydrolysis yields an _______ reaction
Exergonic
Within cells, many biochemical reactions occur through multi-step reactions called ______
pathways
What is a catabolic pathway?
The breakdown of biological products that has a -(delta)G
*Energy releasing*
What is an anabolic pathway?
Is thought of as building cellular components
Has a +(delta)G
All Chemical Reactions require __________ to get started
What is this called?
All Chemical Reactions require an initial input of energy to get started
This is called Activation Energy
____ allows us to store sugar (sucrose) at room temperature for months or years
Activation Energy
_______ allow reactions to happen that may not happen otherwise
Enzymes
What happens to cells when we eat sugar?
Cells form ATP
Activation Energy:
_______ reactions can use the energy they release to continue
Example?
Exergonic reactions
EX. Once you light your BBQ the heat of the flames keeps the propane burning
_____ reactions will require a continuous energy input
Endergonic
*Keep putting energy in*
What are enzymes? and what are they used for?
Enzymes are protein catalysts
They increase the rate of the reaction
They arent completely used up in the reaction
What are enzymes normally named after?
They are named after the reaction they catalyze
Ends in -ase
Which Enzyme breaks down Starch?
Alpha-Amylase
*It is produced in our saliva*
Define the Substrate
It is the reactant
EX. Starch
Define the Active Site
Where the substrate bines to the Enzyme
*It has to be in that exact spot*
- Lock and key Analogy
What does the enzyme Beta-Lactamase do?
Breaks down the B-Lactam ring of Penicillin
How does Penicillin stops bacteria from growing?
By interacting with the enzyme needed for Peptidoglycan biosynthesis (Transpeptidase)
*Penicillin binds to transamylase*
Both Penicillin and the normal substrate can fit the _____
Active site
The cell wall consists of what?
Of thick peptidoglycan layers
Antibiotic Resistance:
Penicillin resistance is generally due to what?
Due to an enzyme (Beta-lactamase) that degrades the drug
Enzymes are ______ that are/are not consumed by the reaction
Enzymes are catalysts, they are NOT consumed by the reaction
The substrate, lactose, binds to the enzyme _______ forming an _________ complex
The substrate, lactose, binds to the enzyme B-galactosidase, forming an enzyme-substrate complex
*Transition state is reached - tightest binding but least stable*
What does B-galatosidase catalyze?
It catalyzes the breakage of the bond between the two sugars of lactose, and the products are released
T or F: Enzymes are unable to catalyze another reaction
False;
Enzymes can catalyze another reaction
Are reactions catalyzed by enzymes still chemical reactions?
Yes therefore the activation energy must still be overcome
Do enzymes alter the (delta)G of the reaction?
Yes
How do Enzymes decrease the Activation Energy?
Less energy has to be put in the reaction
It can do the same thing but at a faster rate
Enzymes decrease the Activation Energy required by _________ of the ______
What does this do to the reaction rate?
Enzymes decrease the Activation Energy required by inducing fit of the substrate
It speeds up the reaction rate and energy levels are not changed!!
Reactants are brought together in the correct orientation, or charges on the ____ can be masked by the _______
Reactants
Enzyme
Induced fit can also ___________.
Which ______ the activation energy and can ________ the break down of a reactant
Induced fit can also strain the bonds of a reactant
*Add stress but makes bond less stable*
Which lowers the activation energy and can speed up the break down of a reactant
What are the 4 factors affecting Enzyme function?
1) pH
2) Salt Concentration
3) Temperature
4) Availability of Substrate
pH:
What are most active at pH2?
Stomach digestive enzymes such as pepsin
pH:
What does low pH do?
They inhibit enzymes by altering their 3D strucure
Salt Concentration:
What will interfere with the chemical bonds in the enzyme, altering the 3D structure?
High levels of Salt
Salt Concentration:
What can high levels of salt also cause?
It can also cause the substrate not to bind due to the ionic charge
Temperature:
At high/low temperature protein will denature altering the 3D shape, affecting the __________
At high temperature protein will denature altering the 3D shape, affecting the lock and key mechanism
Just like pH, an enzyme will have an ______ temperature for activity
optimum temperature
Availability of Substrate:
What happens if there is no available substrate?
Then the enzyme cannot catalyze the reaction
Enzymes can be altered by the ______ and ______
Enzymes can be altered by the reactants and the products
____ can bind to the enzyme active site and block the reactant’s access
Inhibitors
*Can’t be broken down*
When are substrates unable to bind?
Competitive inhibitor molecule resembles _____ and competes for ______
Unable to bind when the inhibitor is bound to the active site
Competitive inhibitor molecule resembles substrate and competes for active site
Other types of inhibitors can bind to a remote site on the enzyme an cause what? Which blocks?
And cause a change in the protein shape that block the reactant’s access to the active site
_________ is common in complex biological pathways
It allows the amount of the ultimate product to be _______ by the cell
Enzyme inhibition is common in complex biological pathways
It allows the amount of the ultimate product to be highly regulated by the cell
What is feedback inhibition?
As the product becomes more abundant, it blocks the pathway which is required for its synthesis
Many drugs are commonly used for?
used to block the activity of specific enzymes
EX. Tylenol blocks pain
Cholesterol pills lower cholesterol
Drugs that block enzyme function:
Selective Serotonis
Reuptake inhibitors stop, and the enzyme needed for serotonin reabsoption- leaving more serotonin in the synapse between nerve cells
This result is ______
altered brain chemistry
What are enzyme cofactors?
Vitamins or metal ions
Enzyme Cofactors are often critical for ?
The induced fit of the substrate, or for electron transfer/storage
Vitamin b6 is required for the synthesis of?
Amino Acids
What is the difference between competitive and non competitive inhibition?
Competitive- 2 fighting for the same spot but only one can bind
Noncompetitive - binds to the enzyme making it not work
Propane is thermodynamically unstable, why is it kinetically stable?
a) It is highly electronegative
b) Its breakdown is exergonic (-G)
c) Its breakdown is endergonic (+G)
d) It has a high activation energy (EA)
e) It contains and abundance of oxygen and little hydrogen
d) It has a high activation energy (EA)
Compared with competitive inhibition, which of the following statements is correct only for noncompetitive inhibition of an enzyme?
a) It changes the conformation of the enzyme
b) The inhibitory molecule is similar in shape to the normal substrate
c) Inhibition decreases the rate at which the product is made
d) It results in the enzyme becoming permanently inactive
a) It changes the conformation of the enzyme
What are the laws of thermodynamics?
1) Conversation of energy
2) Entropy - disorder
Why are enzymes critical for biological reactions?
1) Lowers the temperature
2) Lower the activation energy (how much is needed to start)