Photosynthesis and Cellular Respiration

ENERGY and LIFE  All living things need energy in order to carry out life processes.  Plants are called autotrophs because they are able to use light energy from the sun to produce their own food.  Other organisms, like animals, cannot do this. They must get their energy from another source, so they are called heterotrophs.

 The main chemical compound that cells use to store and release energy is ATP.  ATP – Adenosine Triphosphate  Adenine  3 phosphate groups  Ribose (a 5-carbon sugar)  ADP – Adenosine Diphosphate  Adenine  2 phosphate groups  Ribose

 The phosphate groups are the key to storing and releasing energy.  Storing Energy  When a cell has available energy, it can store small amounts by adding a phosphate group to an ADP molecule creating ATP  ATP is like a charged battery ready to power the cell

 Releasing Energy  When a cell needs energy, the chemical bond between the 2 nd and 3 rd phosphate group is broken. This releases stored energy.  This energy can be used for active transport, protein synthesis and muscle contraction.

PHOTSYNTHESIS  What is it?  Photo – Light+ Synthesis – Putting Together  Using light to put something together (food)  Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into high energy sugars and oxygen  Chemical Equation  6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2  In addition to H 2 O and CO 2, photosynthesis requires light which must be absorbed by the pigment chlorophyll

 Where does this take place?  Photosynthesis takes place within the chloroplasts  Structures of the chloroplast  Thylakoids – photosynthetic membranes  Granum - stacks of thylakoids  Stroma – the space outside the thylakoids

 How does this process work?  Light-Dependent Reaction  Takes place in the thylakoids  Function:  Produce oxygen  Converts ADP and NADPH + into ATP and NADPH *NADP + = an energy carrier molecule  The Calvin Cycle  Takes place in the stroma  Function:  Uses ATP and NADPH to produce high-energy sugars

 Factors that affect photosynthesis…  Water availability  Temperature  Light intensity

CELLULAR RESPIRATION  What is it  Glukus – Sweet+ Lysis – Decomposing  Breaking down sugar/glucose  The process that releases energy by breaking down glucose and other food molecules in the presence of oxygen.  Chemical Equation  6O 2 + C 6 H 12 O 6 6CO 2 + 6H 2 O + Energy  There are two forms of cellular respiration  Aerobic Respiration – occurs in the presence of oxygen  Anaerobic Respiration – occurs in the absence of oxygen

 Where does this take place?  Cellular respiration takes place in the cytoplasm and mitochondria  Structures of the mitochondria  Outer membrane  Inner membrane  Cristae – folds in the membrane that increase surface area to allow more chemical reactions to take place  Intermembrane space – between the outer and inner membrane  Matrix – fluid within the inner membrane

 How does this process work?  Glycolysis  Takes place in the cytoplasm  One molecule of glucose is broken in half to provide chemical energy to the cells  Does not require oxygen

 If oxygen is NOT present….Fermentation occurs  Alcoholic Fermentation  Results in the production of CO 2, ethyl alcohol and small amounts of energy  Occurs in the formation of bread (yeast)  Lactic Acid Fermentation  Results in the production of lactic acid and small amounts of energy  It regenerates NAD+ to enter back into glycolysis  Lactic acid is produced in your muscles during exercise; if there is a build up of lactic acid you will experience a painful, burning sensation in your muscles  Also used in the production of foods such as cheese, yogurt and sour cream

 If oxygen IS present…  Krebs Cycle  Occurs in the matrix of the mitochondria  Produces high energy electrons and small amounts of ATP  Goes through this cycle two times

 Electron Transport Chain  Occurs in the inner membrane of the mitochondria  Uses the high energy electrons from the Krebs cycle to convert ADP into ATP

 Efficiency of Cellular Respiration  Produces a total of 36 ATP molecules  This represents 38% of the total energy of glucose  The remaining 62% is lost as heat produced from carrying out life processes

Photosynthesis vs. Cellular Respiration PhotosynthesisCellular Respiration Organism PlantsPlants and Animals Function Energy captureEnergy release Location ChloroplastsMitochondria Reactants CO 2 and H 2 O (energy)C 6 H 12 O 6 and O 2 Products C 6 H 12 O 6 and O 2 CO 2 and H 2 O (energy) Equation 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 6O 2 + C 6 H 12 O 6 6CO 2 + 6H 2 O