Cellular Respiration and Thermoregulation PDF

Cellular Respiration and Thermoregulation  What is energy? Energy: the capacity to bring about movement against an opposing force; ability to do work Forms of Energy Potential energy: stored energy Chemical energy Ex. Hydroelectric dam, food Kinetic energy: energy...

Cellular Respiration and Thermoregulation  What is energy? Energy: the capacity to bring about movement against an opposing force; ability to do work Forms of Energy Potential energy: stored energy Chemical energy Ex. Hydroelectric dam, food Kinetic energy: energy in motion Running, biking, flying, etc.…  Thermodynamics First Law of Thermodynamics: energy cannot be created or destroyed, only transformed Excess energy released as heat Second Law of Thermodynamics: energy moves from order to disorder Entropy: the amount of disorder  Exergonic and Endergonic Reactions Exergonic reactions: reactants contain more energy than the products Energy released Ex: Cellular respiration Endergonic reactions: products contain more energy than reactants Energy required Ex: Photosynthesis  Exergonic and Endergonic Reactions Cellular respiration: process by which all living things extract energy stored in the chemical bonds of molecules and use it to fuel cellular processes. Photosynthesis: conversion of solar energy to chemical energy  Cellular Respiration and Photosynthesis Photosynthesis Light energy 6H2O + 6CO2 C6H12O6 + 6O2 Water + Carbon dioxide Glucose + Oxygen Cellular Respiration C6H12O6 + 6O2 6CO2 + 6H2O + 36ATP + Heat Glucose + Oxygen Carbon dioxide + Water + 36ATP + Heat  The Molecular Unit of Currency Adenosine triphosphate (ATP) Energy transfer molecule Adenosine diphosphate (ADP) Phosphorylation: addition of a phosphate group to a molecule Most important energy transfer molecule in living things!  Energizing ATP Adenosine triphosphate (ATP) and Adenosine diphosphate (ADP)  Oxidation Reduction Reactions Oxidation: the process of losing electrons Reduction: the process of gaining electrons Reduction in charge Oxidation and Reduction reactions are always linked Redox reaction: the transfer of electrons from one molecule to another  + Oxidation and Reduction of NAD Nicotinamide adenine dinucleotide (NAD+): transfers electrons from hydrogen atoms  + Energy’s Taxi Service: NAD Cellular Respiration Four-part process that converts a single glucose molecule to 36 ATP 1. Glycolysis 2 ATP 2. Transition Phase No ATP produced 3. Krebs cycle 2 ATP 4. Electron transport chain 32 ATP Macromolecules and Energy Why do we have to eat food? Through the cellular respiration process, stored energy in chemical bonds of sugar and other macromolecules is captured and converted into the bonds of ATP. Used in the production of tissue or excreted as waste  Glycolysis Breakdown of 1 glucose molecule into 2 pyruvate molecules Present in all living things Takes place in the cytosol (outside of mitochondria) Two stages Energy investment stage: requires 2 ATP Energy harvesting stage: produced 4 ATP and 2 NADH  Glycolysis 1. 2 ATP are used to attach two phosphate groups to the 6-carbon glucose molecule 1 2. 6-carbon glucose split into two 3-carbon molecules 2 3. Phosphate added with energy from NAD+ oxidation 3 Two NADH molecules produced 4 4. Phosphate groups lost to ADP 5 Four ATP produced 5. Pyruvate end product  Transition Phase Coenzyme A (acetyl CoA) added to pyruvate, Acetyl Coenzyme A produced Carbon dioxide byproduct One NADH molecule produced from each pyruvate molecule Takes place in the inner compartment of mitochondria  Krebs Cycle Takes place in the inner compartment of mitochondria One glucose molecule = 2 pyruvate = Two cycles 4 CO2 6 NADH 2 ATP 2 FADH2  Krebs Cycle 6) 4C malic acid oxidized by 1) Acetyl CoA combines with NAD+ to form 4C oxaloacetic acid to form oxaloacetic acid 6C citric acid 1 NADH 2) 6C Citric acid 5) 4C succinic acid oxidized to form 5C oxidized by FAD to α-ketoglutaric acid form malic acid 1 NADH 1 FADH2 1 CO2 3) 5C α-ketoglutaric acid loses 4) 4C α-ketoglutaric acid carbon, becomes 4C derivative spilt to make α-ketoglutaric acid derivative 4C succinic acid 1 NADH 1 ATP 1 CO2  Krebs Cycle 1. Acetyl CoA combines with 4-carbon & forms 6-carbon compound. 1 2. 6-carbon compound oxidizes to NAD+, producing NADH and releasing 2 CO₂. 5 3. The 4-carbon compound rearranges, generating ATP. 2 4. Oxidizes by FAD to form FADH2. 5. It regenerates the original 4-carbon 4 compound, completing the cycle. 3  Electron Transport Chain Electron Transport Chain: Energy from electrons pumps H+ ions from the inner to outer compartment against their gradient. Inner membrane of mitochondria Oxygen is the final electron acceptor Chemiosmosis: Ion movement across a semipermeable membrane, down their electrochemical gradient. ATP synthase: enzyme uses energy from H+ ions, which adds a phosphate to ADP making ATP  Check Your Understanding CO2 CO2 CO2 4-Carbon H+ H+ H+ compound 6-Carbon H+ H + + H+ H+ H + H+ H compound H+ H+ H+ H+ H+ H+ H+ H+ CoA + H + + __ATP H+ H+ H+ H + H 8 + H + H + + H + H+ H + H + H H+ H H+ H + H+ H H+ H+ H+ H + H + CoA 4-Carbon __NADH __FADH2 compound __ATP 8 __NADH CO2 e- e- CO2 e- CoA __NADH H+ __NADH __FADH2 H+ H+ H + H+ + H+ ADP + P H 4-Carbon __ATP CoA compound 6-Carbon 8 compound ___ + 2H+ = H2O __ATP 8 CO2 4-Carbon __NADH compound __FADH2  Check Your Understanding Glycolysis Transition Phase CO2 CO2 Electron transport chain Chemiosmosis CO2 4-Carbon H+ H+ H+ compound 6-Carbon H+ H + + H+ H+ H + H+ H compound H+ H+ H+ H+ H+ H+ H+ H+ CoA Krebs Cycle + H + + __ATP 1 8 H+ H+ H+ H + H + H + H + + H + H Pyruvate + H H+ H + H+ H Acetyl Co-enzyme A H+ H + H+ H H+ H+ H+ H + H + CoA 4-Carbon 3 __NADH 1 __FADH compound 2 28 __ATP 2 __NADH CO2 e- e- Glucose CO2 CoA e- 2 __NADH H+ __NADH 10 2 __FADH 2 H+ H+ H + H+ + H+ ADP + P H 4-Carbon __ATP 32 CoA compound 6-Carbon 8 compound ½___ O2 + 2H+ = H O 2 Pyruvate Acetyl Co-enzyme A Krebs Cycle __ATP 1 8 ATP Synthase CO2 4-Carbon 3 __NADH compound 1 __FADH 2  Cellular Respiration Review Step Location Input Output Electron Carriers ATP Energy captured in Glycolysis Cytosol Glucose Pyruvate 2 ATP 2 NADH Energy captured in Transition Inner compartment of Pyruvate, Acetyl-Coenzyme-A, - 2 NADH Phase mitochondria Coenzyme-A, CO2 Energy captured in Inner compartment of Acetyl 2 ATP Krebs Cycle CO2 6 NADH, 2 FADH2 mitochondrion Coenzyme-A Energy released Electron Inner membrane of from 10 NADH, 32 ATP Transport Oxygen (O2) H2O mitochondrion 2 FADH2 Chain  Aerobic and Anaerobic Pathways Anaerobic: without the use of oxygen Glycolysis Fermentation Aerobic: with the use of oxygen Cellular respiration  Anaerobic Pathway Fermentation: metabolic pathway that regenerates NAD+ from NADH and allows for glycolysis to continue making ATP in the absence of oxygen Alcohol fermentation Yeast in anaerobic environment Lactic acid fermentation Occurs in animals when ATP use exceeds oxygen uptake  Alcohol Fermentation Ethanol is produced when acetaldehyde accepts electrons from NADH.  Lactic Acid Fermentation Lactic acid is produced when pyruvate accepts electrons from NADH Occurs when oxygen delivery to cells is lagging Causes burning in muscles Anaerobic and Aerobic Contributions Energy from anaerobic respiration is used for short bursts of activity  Check Your Understanding 1. True or False: When NAD+ accepts an electron from a hydrogen it has been reduced 2. True or False: Oxygen is required to make ATP 3. True or False: Cellular respiration is considered an endergonic reaction because it releases energy  Check Your Understanding 3. Which of the following steps produce the most electron carriers? a. Glycolysis b. Transition phase c. Krebs cycle d. Electron transport chain  Check Your Understanding 4. How much ATP is produced as one glucose molecule moves through the Krebs cycle? a. 1 ATP b. 2 ATP c. 4 ATP d. 32 ATP  Check Your Understanding 5. Which of the following best describes the function of the electron transport chain? a. Transfer electrons on to NAD+ to make NADH b. Breakdown glucose into pyruvate c. Use energy from electrons to power the active transport of hydrogen ions d. Use the energy from electrons to attach phosphate groups to ADP  Check Your Understanding 6. Which of the following best describes oxygen's role in the cellular respiration? a. Byproduct of the Krebs cycle and transition phase b. Used to break down the glucose molecule c. Accepts the electron at the end of the electron transport chain d. Donates a phosphate group to ATP  Homeostasis Homeostasis: a physiological state where internal conditions are stable and constant Regulators: use internal mechanisms to control external fluctuations Conformers: allow internal conditions to change in response to external fluctuations  Thermoregulation Thermoregulation: Process by which animals maintain their body temperature within a normal range Endothermic: body temperature maintained by metabolic heat Birds, mammals, and some insects Ectothermic: body temperature controlled by external sources Most reptile, fish, and invertebrates Poikilotherm: animals whose body temperature fluctuates with the environment. Homeotherm: animals with a relatively constant body temperature Variation in Thermoregulatory Strategies Poikilotherms  Heat Exchange with Environment Conduction - direct transfer of heat Convection - transfer of heat by the movement of air or water across a surface Radiation - emission of electromagnetic waves Evaporation - loss of heat from changing a liquid into a gas  Adaptations for Thermoregulation Insulation Hair Feathers Fat (blubber)  Adaptations for Thermoregulation Behavior Responses Basking Huddling Burrowing Hot tubbin’  Adaptations for Thermoregulation Evaporative heat loss Sweating Panting Defecating  Energy Conservation Torpor: physiological state of decreased activity and metabolism Hibernation: long term torpor and a decreased body temperature in response to winter cold and food scarcity Estivation: decreased metabolic rate and activity during hot summer months  Adaptations for Thermoregulation Vasodilation: the widening of superficial blood vessels Increases heat transfer Vasoconstriction: decreasing the diameter of superficial blood vessels  Adaptations for Thermoregulation Counter-current heat exchange 1. Warm blood in arteries from animal's core comes in close contact with veins returning from extremities 2. Blood in arteries remains slightly warmer than blood in veins resulting in heat transfer 3. Returning blood almost as warm as arterial blood Negative Feedback Loops  Animal Diets All animals are heterotrophic: Herbivores Carnivores Omnivores Insectivores Three nutritional needs: Chemical energy for cellular processes Organic building blocks for macromolecules Acquisition of essential nutrients Trade-offs of Thermoregulatory Strategy = = Trade-offs of Thermoregulatory Strategy Trade-offs of Thermoregulatory Strategy What are some of the pros and cons of each thermoregulatory strategy? Endotherms Ectotherms Pros Cons  Trade-offs of Thermoregulatory Strategy Do smaller mammals have higher or lower mass-specific metabolic rates than larger mammals? Why? Smaller endotherms have a greater surface area to volume ratio Lose heat to the environment Must consume more energy to maintain a constant body temperature