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Cellular Respiration and Photosynthesis

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Cellular Respiration and Photosynthesis. *The respiratory system carries oxygen to the circulatory system. *The circulatory system in turn, carries oxygen to every cell in the human body. At the cell level. - PowerPoint PPT Presentation

Text of Cellular Respiration and Photosynthesis


  • *The respiratory system carries oxygen to the circulatory system.

    *The circulatory system in turn, carries oxygen to every cell in the human body.

  • AT THE CELL LEVELOxygen is able to diffuse into the cell while carbon dioxide diffuses out of the cell.Once inside the cell, oxygen moves into the mitochondria. -> the site of cellular respiration

  • with oxygenwithout oxygenGlycolysis

  • Heterotrophs and autotrophs go through the process of cellular respiration to release the energy stored in food.

    Before autotrophs go through the process of cellular respiration they have to go through the process of photosynthesis to make their own food.

    The energy that is released during cellular respiration is packaged in the form of ATP (adenosine triphosphate).

    An overview

  • CELLULAR RESPIRATION*During cellular respiration, glucose combines with oxygen to produce carbon dioxide and water (and ATP).

    CHO + 6O 6CO + 6HO + Energy (Glucose + Oxygen Carbon Dioxide +Water+ ATP)

    *For heterotrophs (like us!) the glucose comes from the food we eat.

  • The bond linking the last phosphate group is a high energy bond. When the third phosphate is removed and bonded to another compound, it transfers the energy to the other compound. ATP stands for adenosine tri-phosphate.



    *Glycolysis takes place in the cytoplasm. During glycolysis, 1 glucose molecule is broken down into 2 molecules of pyruvic acid.

    *4 ATP molecules are formed; however, glycolysis requires 2 ATP to break apart each molecule of glucose; therefore, the net energy produced during glycolysis is 2 ATP.

    * If oxygen is present, glycolysis leads to two other pathways; the Krebs cyle and the electron transport chain. -> this is an aerobic pathway.


    Anaerobic without oxygen

    Aerobic respiration requires oxygen and anaerobic respiration is carried out without the presence of oxygen.

  • KREBS CYLE & ELECTRON TRANSPORT CHAINThe final two stages of cellular respiration take place in the mitochondria.The Krebs cycle occurs in the matrix of the mitochondria.The electron transport chain occurs in the inner membrane of the mitochondria.

  • During the Krebs cycle and the electron transport chain, pyruvate is further broken down and 34 more ATP are produced.


    If oxygen is NOT present, fermentation occurs after glycolysis.-> this is an anaerobic pathway

    * No ATP is produced during fermentation; thus, all of the energy generated during anaerobic respiration is made during glycolysis.

  • FERMENTATION CONT. Alcoholic Fermentation -> produces ethyl alcohol and carbon dioxide Example -> yeast

    Lactic Acid Fermentation -> produces lactic acid and carbon dioxide Examples -> muscle cells, certain bacteria

  • with oxygenwithout oxygenGlycolysis

  • REVIEW OF CELLULAR RESPIRATIONTRUE/FALSE1) Cellular respiration that is carried out without oxygen is aerobic. __________2) Glucose serves as a reactant during cellular respiration. __________3) Heterotrophs obtain glucose as a product of photosynthesis. ___________ 4) During cellular respiration, energy is produced in the form of ATP.___________5) The electron transport chain occurs during aerobic respiration. ___________

  • REVIEW OF CELLULAR RESPIRATIONTRUE/FALSE6) Glycolysis takes place in the mitochondria. _______7) The process that breaks a glucose molecule in half is fermentation. ________8) During aerobic respiration, the majority of ATP is made in the mitochondria. ________9) Anerobic respiration is more efficient than aerobic respiration at making ATP. _______10) Yeast cells undergo fermentation. ____


  • PHOTOSYNTHESISWhere does all of the energy needed to sustain life come from? ____________________

  • The arrows below indicate the flow of ENERGY.The sun gives off energy in the form of light and heat. Plants are able to absorb sunlight.

    During photosynthesis, autotrophs (like plants) use the sunlight to produce their own food (glucose).

    Heterotrophs (like us!) cannot make their own food -> they must consume plants and other animals to obtain glucose.

  • AUTOTROPHS VS. HETEROTROPHS Autotrophs are organisms that make their own food from inorganic substances.

    Heterotrophs are organisms that cannot synthesize their own food and must obtain in ready-made.

  • The following equation summarizes the process of photosynthesis.Carbon Dioxide + Water Glucose+ OxygenSunlight

  • SOME DETAILSThe process of photosynthesis begins when light is absorbed by pigments in the plant cell.

    The most important photosynthetic pigment in plants is chlorophyll: this is what gives plants a green color

  • Chlorophyll is found in the chloroplasts -> an organelle found only in plant cellsMesophyll Cell

  • More specifically, chlorophyll is found within the thylakoids of chloroplasts.

  • SUMMARY OF PHOTOSYNTHESIS 1. Chlorophyll inside the chloroplasts absorbs photons of light. (a photon is a particle of light with a fixed amount of energy).2. The energy is used, along with carbon dioxide, to blow water apart.3. Glucose is produced.4. Oxygen is released.


  • *Photosynthesis and cellular respiration are complementary processes. Photosynthesis uses the energy of sunlight to produce sugars.The same sugars in turn serve as food (for both authotrophs and heterotrophs).Cellular respiration uses O and forms CO from the same carbon atoms that had been taken in as CO and converted into sugars during photosynthesis.


    1) Heterotrophs can produce their own food. __________2) The chemical equation for photosynthesis is the opposite of the chemical equation for cellular respiration. __________3) Photosynthesis uses the energy from sunlight to produce water and carbon dioxide. _________ 4) Photosynthesis occurs in the mitochondria. __________5) It makes sense to talk to your plants. __________