Bio 12o Unit 3 Flashcards
Chapter 8, 9, and 10
2 Types of Energy Exist: Kinetic and Potential Energy
Kinetic: energy in motion
Potential: energy that is stored in position
1st Law of Thermodynamics
Energy can not be created or destroyed it can only be transfer or transformed
Potential Energy in Bonds= Chemical Energy
-Depends on positioned electrons
-Weaker bonds with equally shared electrons= high potential energy
-Stronger bones with unequally shared electrons= low potential energy
Reactants
-Weaker bonds with equally shared electrons
-HIGH potential energy
Products
-Stronger, shorter, more polar bonds
-LESS potential energy
What the engine needs»products of combustion
C8H18+12.508>8 CO2+9 H20
Isooctane+ oxygen> Carbone Dioxide+ Water
EntHalpy (H): total energy molecules
-Potential energy of the molecule effect of the molecule on the surrounding pressure and volume
-Net: total energy on bio systems
-Changes in enthalpy are primarily base on the difference in potential energy
-H< (neg.=products have lower pot. energy)
-H> (pos.= products have higher pot. energy)
Exothermic Reaction
-Release heat energy
-H<0
-Products have less pot. energy that reactant
- Ex. gas
Endothermic Reactions
-Heat energy is taken up
-H>0
-Products have higher pot. energy that reactant
-Ex. cooking and egg, melting ice
Entropy (S): amount of disorder
-Products of a chem reaction becomes less ordered than the reactant molecules
-Entropy increase
-S>0
2nd Law of Thermodynamic
-Entropy always increases
-Energy is transformed, there is always an increase of entropy
Entropy Order
Highly ordered» Increase entropy»disordered
Gibbs Free Energy(G): determines whether a reaction is spontaneous or requires add energy
Free energy change equation: G=H-TS
H= change in enthalpy
S change in entropy
T= temp. in degree Kelvin
Gibbs Free Energy (G)
G<0: Spontaneous reaction, reactions are exergonic
G>0: Nonspontaneous reactions that require energy, reactions are endergonic
G=0: reaction at equilibrium
Collision Theory
More collisions= Increase rate of reaction
Temp. & Concentration Affect Reaction Rates
-One or more chem. bonds have to break and others have to from
-Substances must collide in a specific orientation that brings the electrons involved near each other
-Higher concen. and higher temp. increase the number of collisions
-Higher concen. and higher temp. increase reaction rate
Energetic Coupling
-Between exergonic and endergonic reactions
-Allows chem. energy released from 1 reaction
-Drive another reaction
Ex. of Energetic Coupling: Redox RxNs
-Reduction, Oxidation reactions
-Redox reactions
-Chem. reactions have involve electron(e-) transfer= energy transfer
-Always occur together
-Represent energetic coupling of 2 half reactions
-During a redox reaction, e-: can be transferred or shifted
Redox RxNs Transfer Energy vis Electrons
Oxidation: loss of electrons, releases energy, exergonic
Reduction: gain of electrons, requires energy, endergonic
OIL RIG
-Oxidation Is Loss( of e-)
-Reduction Is Gain(of e-)
G=H-TS
Exergonic
G<0
Spontaneous
Reactants: Weaker bonds, higher potential energy»Products: stronger bonds, lower potential energy
Redox reactions are central in biology- they transfer energy in the form of electrons
The energy released from certain key redox reactions is used to drive the endergonic formation of ATP
ATP Transfers Energy via Phosphate Groups
Adenosine Triphosphate(ATP) is the energy currency for cells
-Provided the fuel for most cellular actives
ATP forms both between 3 neg. change phosphate groups.
-Neg. charges repel each other
-High-energy bonds store a large amount of potential energy
ATP Hydrolysis Releases Free Energy
Hydrolysis of the bond between the 2 outermost phosphate groups results.
Forms ADP and P(inorganic phosphate)
-Highly exergonic reactions+ 7.3 kilocalories of energy per mole of ATP
How does ATP Drive Endergonic Reactions
Energy release during ATP hydrolysis is transferred to a substrate by phosphorylation
-Phosphorylation is adding a phosphate group
-Usually causes a change in the proteins shape
Exergonic phosphorylation reactions are coupled to endergonic reactions
Hoe Enzymes Work
Most bio chem reactions occur fast enough only in the presence of an enzyme
-Enzymes are protein catalyst
-Bring reactants together in precise orientations
-Make reactions more likely
-Are specific for a single type of reactions
Enzymes Help Reactions Clear 2 Hurdles
Before a reaction can take place reactants must
1.Collide in a precise orientation
2.Have enough kinetic energy to overcome repulsion between electrons that come into contact as a bond forms
Collide in a precise orientation? Enzymes Bring Substates Together
Substrates bind to the enzymes active site
-Enzymes help them collide in a precise orientation
-Bonds break and form to generate products
Active site is very specific to the substrate
Many enzymes undergo a conformational change when the substrates are bound to the active site
-This change is celled in induced fit
Substrates bind via hydrogen bonding or other interactions with amino acid residues in the active site
-An unstable intermediate condition called Transition State is formed
-Activation energy(Ea) is required to strain substrates bonds so they can reach the transition state
Have enough kinetic energy… Enzymes Lower the Activation Energy
Interactions between the enzymes and the substate
-Stabilize the transition state
-Lower the activation energy required for the reaction to proceed
Enzymes are not consumed during the reaction
What limits the Rate of Catalytic Reactions(R)?
The speed of enzyme-catalyzed reaction
1. Increase linearly at a low substrate concentrations
2. Slows as substrate concertation increases
3. Reaches maximum speed at high substrate concentrations
Do Enzymes Work Alone?
Many enzymes are not regulated by molecules that are not part of the enzymes itself.
- Cofactors are inorganic ions, such as ZN2, Mg2 and Fe2 that are reversibly interact with enzymes
- Coenzymes are organic molecules such as NADH or FADH that interact with enzymes
- Prosthetic groups are non amino acid atoms or molecules that are permanently attached to proteins
An enzymes structure is critical to its function(dependent on folding)
Enzyme function is dependent on certain conditions
-Temp affects the folding and movement of the enzyme and its substrate
-pH affects the enzymes shape and reactivity
-Each enzymes has optimal temp and pH
Most Enzymes are Regulated: Non Covalent modifications
By regulatory molecules that are not part of the enzyme
-Can control when and where an enzyme functions by changing: Enzyme structure: Ability to bind its substrate
-Can activate or inactive the enzyme
-Does not permanently affect the enzyme structure: reversable
-Can be competitive inhibition or allosteric regulation
Competition inhibition
Occurs when a molecule competes with the substrate for the active site
Allosteric regulation(ACTIVATION)
Occurs when a molecule binds at a location other than the active site and cause a change in a enzyme shape…ACTIVATION
Allosteric Regulation(DEACTIVATION/INHIBITION)
Occurs when a molecule binds at a location other than the active side it causes a change in enzyme shape… DEACTIVATION/INHIBTION