Energy in a Cell All Cells Need Energy Cells need energy to do a variety of work: Making new molecules. Building membranes and organelles. Moving molecules.

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  • Energy in a Cell

  • All Cells Need EnergyCells need energy to do a variety of work:Making new molecules.Building membranes and organelles.Moving molecules in and out of the cell.Movement.

  • Where Does A Cell Get Energy? Food is broken down to a form the cell can use.Extra energy is stored in an ATP molecule, a nucleotide.

  • What Is ATP?ATP adenosine triphosphate is a molecule made up of an adenine, ribose, and 3 phosphate groups.AdenineRibose

  • How Does ATP Work?Energy is stored in the bond between the second and third phosphate group.When the bond is broken, energy is released and ADP is formed. AdenineRibose

  • ATP Energy CurrencyWithin a cell, formation of ATP from ADP and phosphate occurs over and over, storing energy each time.As the cell uses energy, ATP breaks down repeatedly to release energy and form ADP and phosphate.

  • Making EnergyCells make energy in two ways:Photosynthesis takes place in the chloroplasts.Respiration takes place in the mitochondria.

  • PhotosynthesisAutotrophs make their own food by trapping light energy and converting it to chemical energy (carbohydrates).

  • PhotosynthesisUsing light from the sun, plants combine water and carbon dioxide to make sugar .General Equation:6CO2 + 6H2O + energy C6H12O6 + 6O2Reactants Products

  • Photosynthesis2 ReactionsLight ReactionsCalvin Cycle

  • PhotosynthesisLight Reactions Light energy is converted to chemical energy to split hydrogen from water.Takes place in the grana of the chloroplasts (the coin-like stacks of sacs).Byproducts are oxygen, NADPH, and ATP.

  • PhotosynthesisCalvin Cycle ATP and NADPH from the light reactions are used along with CO2 to form a simple sugar (glucose).Takes place in the stroma of the chloroplasts (the liquid filling).Byproducts are C6H12O6 (glucose), ADP, and NADP+ (which return to the light reactions).


  • ChemosynthesisSome autotrophs can convert inorganic substances to energy.Most are adapted to live in conditions where there is no oxygen.Marshes.Lake sediments.Digestive tracts of mammals.Deep in the ocean.

  • RespirationThe process of breaking down food molecules to release energy.Occurs in the mitochondria.Two types:Aerobic requires oxygen.Anaerobic requires an absence of oxygen.

  • RespirationTwo types of anaerobic respiration:Fermentation occurs when bacteria break down plants (vegetables and fruit) and release alcohol or vinegar.Lactic Acid Fermentation occurs in muscles a buildup of lactic acid causes soreness.

  • RespirationStepsGlycolysisCitric Acid CycleElectron Transport Chain

  • RespirationGlycolysis glucose is split to form pyruvate.Takes place in the cytoplasm of the cell.ATP is a byproduct.

  • RespirationCitric Acid Cycle pyruvate is used to build citric acid (a carbon compound), which is broken down to release ATP.Takes place in the cristae (the folded membrane in the mitochondrion).CO2 is released, and NADH carries hydrogen ions to the electron transport chain.

  • RespirationElectron Transport Chain hydrogen ions are stripped of their energy, and large amounts of ATP are formed.Takes place in the inner membrane of the mitochondrion.The used ions are combined with oxygen to form H2O.

  • MITOCHONDRIONCO2H2OO2ATPNADHHeatElectronTransportSystemATPNAD+PyruvateGlucoseATP

  • SunlightPhoto-SystemIPhoto-systemIINADP+ADPNADPHATP




  • SunlightPhoto-SystemIPhoto-systemIINADP+ADPNADPHATPCycle




    This is a Black Smoker in the Pacific. A tubular hydrothermal vent that releases hot water, known as a "black smoker", in the Pacific Ocean.


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