Lesson Overview 9.1 Cellular Respiration: An Overview

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  • Lesson Overview9.1 Cellular Respiration: An Overview

  • THINK ABOUT ITYou feel weak when you are hungry because food serves as a source of energy. How does the food you eat get converted into a usable form of energy for your cells?

  • Chemical Energy and FoodFood provides living things with the chemical building blocks they need to grow and reproduce.

    Food molecules contain chemical energy that is released when its chemical bonds are broken.

  • Chemical Energy and FoodEnergy stored in food are calories.

    A Calorie is the amount of energy needed to raise the temperature of 1 gram of water by 1 degree Celsius.

    1000 calories = 1 kilocalorie, or Calorie.

    Cells use the energy from fats, proteins, and carbohydrates..

    Cells break down food molecules to make ATP

  • Comparing Photosynthesis and Cellular Respiration

    What is the relationship between photosynthesis and cellular respiration?


  • How ATP is Produced: Cellular Respiration INOutGlucoseOxygenADPFree Phosphate (P) Carbon DioxideWaterMitochondrionThe ATP can be used directly to power life processes ATP

  • Capturing Light Energy: Photosynthesis Requirements and products of photosynthesis INOutCarbon DioxideWaterLight EnergyGlucoseOxygenWaterChloroplast

  • Overview of Cellular RespirationWhat is cellular respiration?Cellular respiration is the process that releases energy from food in the presence of oxygen.

    In symbols:6 O2 + C6H12O6 6 CO2 + 6 H2O + Energy

    In words:Oxygen + Glucose Carbon dioxide + Water + Energy

  • What forms of energy?

    ATP Adenosine Triphosphate

  • How ATP provides energy ATP links Anabolism (building molecules) and catabolism (breaking down molecules)!!!!!

  • Stages of Cellular RespirationThe three main stages of cellular respiration are


    the Krebs cycle,

    the Electron Transport Chain.WE START HERE!!

  • Glycolysis

    Glycolysis produces only a small amount of energy.

    Glycolysis takes place in the cytoplasm of a cell.

    Gylcolysis is an anaerobic process (no O2 needed)

  • GlycolysisCytoplasm

  • GlycolysisDuring glycolysis, we start with1 molecule of glucose

    We end with2 ATP2 NADH2 molecules of pyruvic acid(these 2 will be used for the Krebs cycle)

  • GlycolysisATP production2 ATP are used to get it started4 ATP are produced during Glycolysis

    SO, a total of 2 ATP are produced for each molecule of glucose that enters glycolysis

  • NADH Production2 NADH molecules are produced for every molecule of glucose that enters glycolysis.During glycolysis, the electron carrier NAD+ (nicotinamide adenine dinucleotide) accepts a pair of high-energy electrons and becomes NADH.- Electrons are carried by NADH to the electron transport chain to make more ATP.

  • The Advantages of GlycolysisGlycolysis produces ATP very fast, which is an advantage when the energy demands of the cell suddenly increase.

    Glycolysis does not require oxygen, so it can quickly supply energy to cells when oxygen is unavailable.


  • Stages of Cellular RespirationWhat molecule is entering the Krebs Cycle?2 Pyruvic Acid MoleculesDuring the Krebs cycle, a little more energy is generated from pyruvic acid.

  • Stages of Cellular RespirationGlycolysis takes place in cytoplasm and requires no oxygen

    Krebs Cycle takes place in mitochondria and requires oxygen

    Electron Transport Chain takes place in mitochondria, requires oxygen and produces A LOT of energy

  • Krebs CycleThe Process of Cellular Respiration

  • The Krebs Cycle

    During the Krebs cycle, pyruvic acid is broken down into CO2

    The Krebs Cycle is also known as the citric acid cycle due to the citric acid that is formed

  • Citric Acid Productionpyruvic acid enters the mitochondria..

    NADH, CO2 and acetyl-CoA form from electrons and carbon atoms.

    Acetyl-CoA combines with a 4-carbon molecule to produce citric acid.

  • Energy ExtractionCitric acid breaks down into a 5-carbon compound and a 4-carbon compound.

    The 4-carbon compound can then start the cycle again by combining with acetyl-CoA.

  • Energy ExtractionBreaking bonds causes a release of energy.

    ATP, NADH, and FADH2 catch and store this released energy.

  • Energy ExtractionRemember! Each molecule of glucose results in 2 pyruvic acids..2 pyruvic acids = two complete turns of the Krebs cycle.2 pyruvic acids make. 6 CO22 ATP8 NADH2 FADH2

  • 2 pyruvic acids enter the Krebs Cycle, but what would only ONE pyruvic acid produce?

    3 CO21 ATP4 NADH1 FADH2

  • Electron Transport and ATP SynthesisHow does the electron transport chain use high-energy electrons from glycolysis and the Krebs cycle?

    The electron transport chain uses the high-energy electrons from glycolysis and the Krebs cycle to convert ADP into ATP.

  • Electron TransportNADH and FADH2 bring their high-energy electrons to electron carrier proteins in the electron transport chain.

  • Electron TransportAt the end of the ETC, electrons combine with H+ ions and oxygen to form water.

  • Electron TransportEnergy from the ETC moves H+ ions up the concentration gradient into the intermembrane space.

    H+ ions are building up

  • ATP ProductionH+ ions pass back quickly across the mitochondrial membrane through the ATP synthase This causes ATP synthase molecule to spin. With each rotation, the ATP synthase makes 1ATP.

    For every glucose molecule, ATP synthase will spin 34 times and 34 ATP are produced.

  • Fermentation

  • FermentationHow do organisms generate energy when oxygen is not available?

    In the absence of oxygen, fermentation releases energy from food molecules by producing ATP.

  • FermentationFermentation is a process by which energy can be released from food molecules in the absence of oxygen. Fermentation occurs in the cytoplasm of cells.

  • FermentationUnder anaerobic conditions, fermentation follows glycolysis. During fermentation, cells convert NADH produced by glycolysis, which allows glycolysis to continue producing ATP.

  • Alcoholic FermentationYeast and a few other microorganisms use alcoholic fermentation that produces ethyl alcohol and carbon dioxide. This process is used to produce alcoholic beverages and causes bread dough to rise.

  • Alcoholic FermentationChemical equation:

    Pyruvic acid + NADH Alcohol + CO2 + NAD+

  • Lactic Acid FermentationMost organisms, including humans, carry out fermentation using a chemical reaction that converts pyruvic acid to lactic acid.

    Chemical equation:

    Pyruvic acid + NADH Lactic acid + NAD+

  • Energy and ExerciseHow does the body produce ATP during different stages of exercise?

    For short, quick bursts of energy, the body uses ATP already in muscles as well as ATP made by lactic acid fermentation.

    For exercise longer than about 90 seconds, cellular respiration is the only way to continue generating a supply of ATP.