BIOL 1107 - EXAM 2

• Gas exchange is the process by which animals exchange gases with their surroundings, delivering oxygen to body cells and removing carbon dioxide from cells to deliver to the surroundings
• For aquatic animals, the respiratory medium is water; for terrestrial animals, it's air; and for amphibians, it's both
• Breathing is the exchange of gases with the respiratory medium
• Respiratory surface is the interface between the body and the respiratory medium:

  • Small animals like sponges and flatworms use their entire body surface as a respiratory surface
  • Larger animals use gills and lungs
• Gills are evaginations of the body that extend outward into the respiratory medium
• Lungs are invaginations of the body, deep in the body interior
• Insects use a tracheal system, a system of branching tubes to channel air from the environment to the internal organs
• Pulmocutaneous System is used by amphibians like salamanders, allowing them to breathe through gills and skin
• Water holds less oxygen than air, and the concentration of oxygen is affected by temperature and the amount of solutes
• Air holds a high concentration of oxygen, has low density and low viscosity, allowing gas molecules to diffuse faster
• Gills in sharks, rays, and skates have gill slits, and they keep their mouths open so water enters, exits through gill slits, using a countercurrent exchange system
• Tracheal system in insects consists of trachea leading from the body surface and branching to almost every cell inside the animal
• Lungs in reptiles and mammals are filled by negative pressure breathing, involving the expansion of lungs, lowering pressure, and pulling air inwards
• Mechanisms of gas exchange and transport involve the Bohr effect, where CO2 is released from oxidative reactions and combines with water to form carbonic acid
• Cellular respiration is a collection of metabolic reactions that break down food to produce energy as ATP, primarily occurring in the mitochondria
• Aerobic respiration involves oxygen as a reactant in ATP production, while anaerobic respiration uses a molecule other than oxygen for ATP production
• Photosynthesis stores energy from sunlight as electron-rich molecules for fuel, while respiration moves electrons from fuel to other molecules to drive ATP synthesis
• Redox reactions involve the removal and addition of electrons to substances, with oxidation releasing energy and reduction gaining energy
• Stages of cellular respiration include glycolysis, pyruvate oxidation, citric acid cycle, and oxidative phosphorylation
• During glycolysis, enzymes break glucose into pyruvate with phosphate group hammer, and some ATP is synthesized by substrate-level phosphorylation
• Pyruvate oxidation and the citric acid cycle involve the complete oxidation of carbon acetyl groups to carbon dioxide, with some ATP synthesized during these processes
• Oxidative phosphorylation involves high-energy electrons delivered to oxygen by a sequence of electron carriers, generating an H+ gradient by chemiosmosis to produce ATP
• Aerobic respiration


  Respiration in eukaryotes and many prokaryotes where oxygen is a reactant in ATP production
• Anaerobic respiration


  Respiration in some prokaryotes where a molecule other than oxygen is used in the production of ATP
• We primarily use ATP as a source of energy
• Respiration


  Process where organisms break down food to produce energy as ATP
• Cellular respiration


  Collection of metabolic reactions that break down food to produce energy as ATP, formed in the mitochondria
• Mammals need to maintain constant internal temperature and need to eat a lot
• Photosynthesis stores energy from sunlight as electron-rich molecules for fuel
• Reduction


  Electrons are added to a substance, resulting in the substance being reduced
• Respiration moves electrons from fuel to other molecules, and electron energy drives ATP synthesis
• Stages of Cellular Respiration: Glycolysis, Pyruvate Oxidation, Citric Acid Cycle, and Oxidative Phosphorylation
• Redox Reactions

  Reactions that remove electrons from a donor molecule and simultaneously add them to an acceptor molecule (oxidation and reduction reactions paired)
• Oxidation


  Electrons are removed from a substance, resulting in the substance being oxidized
• Energy is released from the oxidation of methane, felt as heat energy and seen as light energy
• Oxygen is reduced in cellular respiration in the production of water
• Enzymes stabilize the transition state of chemical reactions and reduce randomness and time taken
• Dehydrogenases transfer 2 electrons and 1 proton to NAD+ (oxidized), resulting in complete reduction to NADH (reduced)
• ATP powers a chemical reaction by breaking apart glucose and harnessing the energy from the broken chemical bonds (the electrons)
• Carrier


  Most commonly NAD+