Lecture Focus Questions; Energy Flashcards
What is Energy?
-It is the capacity to do work/ exert a force on an object
What is Potential Energy?
-Energy stored for later use
What are the 2 different qualities of Energy?
- Free energy= available to due work
- Entropy=Energy lost in disordered states
What different forms of energy are present in Biological systems?
-Electromagnetic energy AKA radiant
-Chemical energy
(we occasionally see thermal & electrical)
What is Entropy?
- It is derived from the 2nd law of thermodynamics
- It is described as the “measure of disorder” of the number of possible atomic arrangments that give rise to the same overall state
- SO the more possible arrangments the more entropy
- Entropy is always increasing in isolated systems
What does the 2nd Law of Thermodynamics state?
- It states that energy transactions cannot be 100% efficient
- SO the energy that is wasted is unusable & disordered due to an increase in Entropy
What concepts are applicable for all systems?
-The concepts of free energy which can be used in isolated systems or open systems like living systems
What equation is used to calculate ▲G & what do the variables mean?
▲G=▲H -T▲S
with H being Enthalpy (total energy)
T for temperature
S for Entropy
What does it mean when a reaction is Spontaneous?
-It is thermodynamically favored to go in the forward direction from reactants to products which have a negative ▲G= Exergonic
What is the difference between Exergonic reactions & Endogornic reactions?
- Exergonic reactions are spontaneous, negative & release negative▲G
- Endergonic reactions are not spontaneous, positive ▲G & consume energy only if energy is provided
What is a key characteristic of chemical reactions?
-They are reversible
How can we predict the direction of a chemical reaction?
- We can do it based on thermodynamics
- SO if a reaction has a negative ▲G (▲G <0) then the reaction will go forward w/ the products predominating
- If a reaction has positive ▲G (▲G>0) then the reaction doesn’t happen & reactants predominate at equilibrium
How is life on earth similar to a refrigerator?
- They are both open systems that can create order w/ input of energy= reducing entropy
- Both still obey the 2nd law of thermodynamics
What is ATP?
- It is an RNA nucleotide that is used as the energy currency of cells
- It doesn’t decay & it is a high energy molecule
What does the Hydrolysis of ATP generate?
- It generates ADP and Pi
- It is also very exergonic which releases 7.3kcal /mol of free energy
How is ATP used in coupled reactions?
-When ATP is hydrolyzed, the energy released is coupled to drive endergonic reactions
Since the hydrolysis of ATP is an exergonic reaction, how can we have ATP at all?
- The hydrolysis of ATP is spontaneous but it will not occur rapidly bc there is a substantial energy barrier that must be overcome
- and that the ATP molecules & its bonds are stable
How do cells stay alive?
-They do it by continually synthesizing new molecules but they need energy to carry out the endergonic synthesis
What is the Activation Energy Barrier?
-It is the energy required to convert one molecule to another that ALL STABLE MOLECULES NEED
What is Kinetics?
-It is the rate of a reaction
What is the difference between Thermodynamics & Kinetics?
- Thermodynamics is when a reaction is spontaneous or not which can be fast or slow
- Kinetics is how fast a reaction is
What is the difference between reactions with large activation energy barriers & low activation energy barrier?
- The reactions with the high activation energy barrier will occur slower
- While the reaction with the low activation energy barrier will occur faster
What is Enzymes?
- They are biological catalysts to speed up reactions by lowering the activation energy barrier without affecting the energy of the reacting molecules
- They DO NOT CHANGE the spontaneity, thermodynamics, or relative predominance of reactants & products
What kinds of molecules are Enzymes?
-Most are proteins w/ a folded 3D structure while some enzymes are RNA molcules
What 3 mechs do Enzymes use to do their job?
- Orient molecules to react better
- They can stabilize the transition rate (highest energy point)
- They can also promote an alternative reaction w/ less activation energy
