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Chapter 6: Capturing and Using Energy (Enzymes increase rate of reaction…
Chapter 6: Capturing and Using Energy
Phototrophs
Autotrophs
Carbon from inorganic sources like CO2 (Cyanobacteria, Vascular plants)
Heterotrophs
Carbon from organic compounds (Heliobacteria, other bacteria)
Chemotrophs
Autotrophs
Carbon from inorganic sources like CO2 (Sulfur-oxidizing bacteria, hydrogen bacteria
Heterotrophs
Carbon from organic compounds (Most bacteria, all animals)
Metabolism: Chemical reactions within cells that convert molecules into other molecules and transfer energy
Catabolism: Breaking down molecules, producing ATP
Anabolism: Building molecules, requires energy input
Energy: The capacity to do work
Potential Energy: Stored Energy, released through motion
Kinetic Energy: Energy of motion
Chemical Energy: Held in bonds
"The more stable configuration will always be the one with lower potential energy"
ATP: (From left to right) Three phosphates, Ribose (5-carbon sugar), Adenine
ATP hydrolysis is an exergonic reaction that releases free energy
First Law of Thermodynamics: The universe contains a constant amount of energy
Second Law of Thermodynamics: The transformation of energy is associated with an increase in disorder of the universe
Entropy: Degree of disorder
Gibbs Free Energy (Delta G): Amount of energy available to do work
Exergonic Reaction: Spontaneous, negative Gibbs
Endergonic Reaction: Non-spontaneous, positive Gibbs
Total Energy (H or Enthalpy)=Gibbs + Temperature x Entropy
ΔG = ΔH – TΔS
Energetic coupling
When a spontaneous reaction drives a non-spontaneous reaction
Enzymes increase rate of reaction by reducing activation energy (ΔG unchanged)
Transition State: Intermediate between reactant and product
Substrate: Molecule acted upon by enzyme
S + E ⇋ ES ⇋ EP ⇋ E + P
Active Site is part of enzyme that binds substrate
Enzymes are influenced by
Inhibitors
Irreversible (covalently bonds to enzyme) and Reversible types
Negative Feedback: final product inhibits the first step of the reaction
Activators
Cofactor: Substance that associates with enzyme, plays role in its function
Allosteric Enzyme: Activity is affected by binding molecule at site other than active site
X-ray crystallography allows us to see the location of atoms in an enzyme
Milk supplemental Lecture
Homogenization reduces size of fat micelles, increases density
Milk is produced in alveoli- then drains into grand cistern
Two major classes of proteins in milk-
Casein- micelles (curds)
Lacalbumin- soluble (whey)