Energy & metabolism Flashcards
How is energy from sunlight stored?
-Stored as potential energy in covalent bonds between atoms in the sugar molecules
How is the strength of the covalent bond measured?
-By the amount of energy that’s required to break it
What happens to the energy stored in chemical bonds during a chemical reaction?
-The energy is used to make new bonds
What is it called when an atom LOSES an electron?
-Oxidation bc oxygen is the most common electron receptor in biological systems
What is called when an atom GAINS an electron?
-Reduction= the reduced form of a molecule has HIGHER energy that oxidation form
What are Redox Reactions?
- When oxidation & reduction take place together
- Play a key role in the flow of energy in biological systems
What is Energy defined as?
-The ability to do work
What does the First Law of Thermodynamics state?
- Energy cannot be created nor destroyed, it can ONLY change from one form to another
- The total amount of energy in the world remains constant
What is Heat?
- Energy that dissipates into the environment
- A Measure of the random motion of molecules
How does Energy flow in the biological world?
-In one one direction w/ new energy from the sun constantly entering the system to replace the energy that’s been dissipated into heat
What is a heat gradient?
-The temperature difference between 2 areas
How can heat be harnessed to do work?
- ONLY when there is a heat gradient present
- But CAN’T work in cells bc they’re too small so cells must rely on chemical reactions for energy
How does the energy available to do work decreases?
-It decreases due to the increasing loss of being turned into heat
What is the 2nd Law of Thermodynamics?
- States that disorder (entropy) is constantly increasing= you CAN’T keep all the useful energy which is why perpetual motion is impossible
- ONLY low to high entropy NEVER high to low entropy
What is Entropy?
- The disorder in the universe
- Low quality, unusable energy
What is Truely High Entropy?
-The entropy state would NOT be distinct
think of different paint colors mixing together to create a different color
What is Low Entropy?
-The entropy state would be MORE distinct= can see a more clear separation
(can see the green and the blue before making purple)
what are the equations expressing the 1st & 2nd law are limited to?
-ONLY applies to ISOLATED systems bc biological systems are open systems
What’s the difference between the 1st & 2nd law regulations?
- The 1st law regulates the AMOUNT of energy
- The 2nd law regulates the DISTRIBUTION of energy & mass
What type of energy makes it easier to pull atoms apart?
-Heat energy bc it increases atomic motion
What influence does Heat vs Chemical bonding have on a molecule?
- Chemical Bonding REDUCES disorder
- Heat INCREASES disorder
What is Free Energy?
- High quality & useful energy BUT always being converted into low quality, unusable energy (entropy)
- Predicts the outcomes of reactions of any systems (open or closed)
What is the Equation for free energy (delta G)
Delta G= Delta H- TdeltaS
Using the Free energy equation, What does it mean when Delta G is Positive?
- The products have MORE free energy than reactants=Endergonic
- NOT spontaneous bc they require an INPUT of energy
Using the Free Energy equation, what does it mean when Delta G is negative?
-Spontaneous reaction= Exergonic
Because chemical reactions are reversible, an Exergonix reaction will be…..
-Endergonic in reverse
What role doe the Equilibrium Constant play when thinking about free energy changes?
- An Exergonic reaction has an equilibrium FAVORING the PRODUCTS
- An Endergonic reaction has an equilibrium FAVORING the REACTANTS
What must happen BEFORE new chemical bonds can form?
-Existing bonds MUST be broken which requires an energy input
What is Activation energy?
-The extra energy needed to stabilize existing chemical bonds & initiate a chemical reaction
What does the rate of an Exergonic reaction depend on?
-Activation energy required for reaction to begin
Reactions with larger activation energies….
-Tend to proceed SLOWER bc fewer molecules succeed getting over the initial energy hurdle
What are 3 ways to increase the rate of reactions?
- Increasing the energy of reacting molecules
- Lowering activation energy
- Use a catalyst to lower the activation energy
What’s the difference between Catalysis & a Catalyst?
- Catalysis is the process of influencing chemical bonds in a way that lowers the activation energy needed to initiate a reaction
- A Catalyst is the substance that gets this process done
How does a Catalyst work?
- They exert their action by affecting an intermediate stage in the reaction= Transition stage
- Then they stabilize this= lowers activation energy
- They DO NOT violate the laws of thermodynamics
What is the direction of a chemical reaction determined by?
-SOLEY by the difference in free energy between reactancts & products
What is the chief currency of energy?
-ATP (Adenosine Triphosphate)
What is ATP used for?
- Building blocks for RNA molecules
- Drive endergonic processes bc it can provide most of the energy a cell needs
What 3 components make up ATP?
- 5 carbon sugar (ribose)= framework for the other 2 subunits to attach to
- 2 nitrogen carbon rings = weakly attracted to hydrogen ions= weak base
- 3 phosphates
How does ATP store energy & how does it get transferred to another molecule?
- Key lies in the phosphate groups bc they’re super negatively charged= have low activation energy & easily broken by hydrolysis
- The hydrolysis of the outermost high energy bond of ATP results in negative delta G which is energy that’s able to produce work= AD plus inorganic Pi
- The liberated phosphate group then temporarily attaches to an immidiate molecule
What makes ATP a poor long term energy storage molecule?
-the inability of its phosphate bonds
How do cells use ATP cyclically?
- Since cells only have seconds worth of ATP
- Cells use Exergonic reactions to provide energy to synthesize ATP from ADP+ Pi
- Then they use hydolysis of ATP to provide energy to drive Endogernic processes
How does the shape of an Enzyme help lower the activation energy of reactions?
- Since it’s a 3D shape, it can stabilize a temporary association between substrates
- By bringing 2 substrates together in the correct orientation or stressing chemical specific bonds, it lowers the activation energy required for new bonds to form
- Enzymes can be reused & only a small amount is needed it won’t be changed/consumed
What do the Enzymes of a cell determine by facilitating specific chemical reactions?
-Can determine the course of metabolism (collection of all chemical reactions in a cell)
What are Enzymes?
- 3D globular proteins w/ one or more pockets= active sites
- Since they’re not ridgid they can induce a better fit when the subtrate comes into the active sites
What is Enzyme-Substrate Complex?
-Substrates binding to the enzyme at their active sites (pockets)
What are the 5 steps for Catalysis to occur within the Enzyme-Substrate Complex?
- Substrate molecule must first fit into the active site
- Then amino acid side groups of the enzyme end up very close to certain bonds of substrate
- The amino acid side group interact chemically w/ substrate by stressing or distorting specific bond to lower activation energy needed to break it
- After bonds are broken/ new bonds form, substrates are converted into products
- Then these products dissociate from the enzyme
