Chapter 3 - Metabolism and Energy Flashcards
Remnote
What is Metabolism
the sum of all chemical reactions in a cell or organism
Anabolic Reactions
- Condensation
- BUILDING of new chemicals
- Stored energy in bonds: making bonds creates stored energy used for other functions (potential energy)
Catabolic Reactions
- Hydrolysis
- BREAKING substances down
- Releases energy
Activation Energy
- Amount of energy needed to DESTABILIZE bonds of a molecule
- breaking bonds in initial reaction uses energy
- TRANSITION STATE
- Reducing Activation Energy: enzymes reduce the amount of activation energy to start a reaction
- MODS
Energy
- contained within chemical bonds
- for a reaction to occur/progress: chemical bonds must be broken
- ability to do work
- energy is used to move an object against an opposing force
Kinetic Energy
→Energy that an object possesses due to its motion
Potential Energy
Stored energy based on an object’s position or state
1st Law of Thermodynamics
Energy cannot be created or destroyed, only transformed.
Chemical Bonds
conversion of energy from one form to another depends on the breaking and formation of chemical bonds
Bond Energy
- Stability of a covalent bond
- energy is absorbed when reactant bonds break
- energy is released when product bonds form
Endergonic Reactions
- reaction ABSORB more energy than is released
- less reactants than products
Exergonic
- reaction RELEASES more energy than is used
- Hydrolysis is exergonic
- more reactants than products
Energy Coupling
use of energy released from one reaction to drive another reaction
Enthalpy
change in energy (heat)
2nd Law of Thermodynamics
Only some of the original energy ends up in the new form; the rest is lost as HEAT
Disorder
- Entropy, which measures the level of disorder in a system
- Organelles getting old and stopping functioning creates disorder/Entropy in the cell
- Restoring order requires energy
Spontaneous
continues on its own; DOES NOT require a continuous supply of energy
Non-Spontaneous
cannot occur without a continual supply of energy
Free Energy (G)
USEFUL energy available to do work in a system (not lost as heat)
Phosphates
- negatively charged and repel from one
- AMP, ADP, ATP
- last phosphate has high energy bond
- easy to break off because of repelling like charges
- energy stored is released
ATP Structure
- Ribose sugar
- Adenine base
- 3 phosphates
Conversion of ATP to ADP
- Hydrolysis
- ADP and inorganic phosphate formed (charged)
- Makes bonds with water (H+): releases lots of energy
- Exothermic
- Increase of Entropy
- Produces free energy
- Reversable reaction - 30 KJ released every time 3rd phosphate is released/attatched
- Aerobic Respiration: glucose gets oxidized; redox reaction
How ATP Works
- repulsion in the O- groups
- Breaking of O-P bond requires little energy ‒ HYDROLYSIS
- Phosphate bonds with water
- releases energy, creates stable structure
- Entropy increases
- exergonic reaction
ADP to ATP
- Phosphorylation: The addition of a phosphate group to a molecule
- energy comes from oxidation of sugars (aerobic respiration)
- 40% of energy released from exergonic reaction is used to do work
Redox Reaction
- when electrons are lost, another must gain
- they provide cellular energy, because the flow of electrons between molecules produces usable energy
Reduction
- charge goes down, gains - charge
- hydrogen is removed, OXYGEN is ADDED
- energy release
Oxidation
- change goes up, loses - charge
- hydrogen is added, OXYGEN is REMOVED
- energy absorption
Coenymes
- Coenzymes are non-protein organic molecules that assist enzymes in catalyzing reactions
- NADP, NADPH
BONUS QUESTION
eg. NAD+
- the reduced form of NAD+ is NADH
- the transfer of energy between NAD+ and food is efficient
- The potential energy carried in NADH facilitates the synthesis of ATP
Oxidizing agent
- The substance that gains electrons
- It oxidizes the other substance
- Eg. Oxygen
Reducing Agent
- The substance that loses electrons
- It reduces the other substance
- Eg. Methane (carbon)
Rapid Combustion
- Eg. burning of glucose
- Oxygen gas does the oxidizing
- Reaction produces CO2 and H2,O and releases energy
- CO2 and H2O are fully oxidized and contain no more available chemical energy
Controlled Oxidation
- Eg. Cellular respiration (controlled oxidation of glucose) in cells
- Oxidation of glucose occurs through a series of enzyme-catalyzed reactions
- Each step releases a small amount of energy following absorption of a small amount of activation energy. The energy released is given to energy-carrying molecules for the next step.
- Cells capture more free energy and produce less thermal energy waste
Energy Carriers
- The oxidation of food molecules often uses enzymes called dehydrogenases
- A dehydrogenase is an enzyme that oxidizes a substrate and transfers hydrogen ion to an acceptor
