Unit 4

• Photosynthesis and Cellular Respiration 


  Both processes transform and store energy

  Are opposite to each other but work together to maintain the oxygen-carbon cycle
• Photosynthesis 


  Uses solar energy (light) to convert CO2 and H2O into carbohydrates (glucose)
• Cellular respiration 


  Uses carbohydrates to make the energy taken used by all cells > ATP
• Photosynthesis occurs partially in the leaves > handout (specifically in the chloroplasts)
• Chlorophyll 


  Is a pigment > a chemical that absorbs different wavelength (colours) of light
• A green plant with chlorophyll absorbs red to blue light but not green > our eyes pick up the reflected green
• Plants contain more than just chlorophyll

  Carotenoids

  Xanthophyll

  Lycopene
• Carotenoids 


  Carrots
• Xanthophyll 


  Bell peppers, bananas
• Lycopene's 


  Tomatoes, eggplants, blueberries
• In summer, chlorophyll is the main pigment seen because lots of sun = lots of photosynthesis
• In fall, cold temps destroys chlorophyll, and the other pigments come through = leaves change colour
• Where does cellular respiration occur?


  In the mitochondria
• Cellular respiration is used to convert glucose from food into ATP > only form of energy that can be used by cells
• The energy in ATP is stored in the bonds between phosphates
• When a bond is broken, energy is released
• If necessary (once all the available ATP has been converted to ADP), the cell can take another phosphate out of ADP to make AMP (mono) > NOT as energy efficient, so last resort
• Cells use ATP for their everyday functions, and cells respiratory replenishes our stores of it
• PS 2 and PS 1 are bundles of chlorophyll that absorbs different wavelength of light
• NADPH is a molecule that creates H+
• Oxidation 


  the loss of electrons
• Reduction 


  The gain of electrons
• Whenever a substance is reduced, it gains electrons and since electrons are energy, the substance has more energy
• When attaching atoms to create glucose, electrons are added therefor increased energy
• Where does light dependent reactions occur 


  In the thylakoids
• Electron Transport Change (ETC)


  A series of reactions where electrons release their energy
• The flow of H+ through the pore generates energy used to attach phosphate to ADP > ATP
• Photosynthesis of H2O


  Broken down by photons in O2, H+, and electrons
• Photosynthesis 2

  The bundle of chlorophyll is struck by photons and 1 electron becomes energized.

  This leaves photosystem 2 one electron short.

  The empty spot if filled by electron made in photolysis
• Photosystem 1

  Same as photosystem 2 but the empty spot is filled by electron that left photosystem 2.

  Goes through ETC generating energy
• Making NADPH


  Found in the chloroplasts

  Need H+ from photolysis

  Need electron, so the thylakoid uses the electron that left photosynthesis 1
• Making ATP


  As H+ accumulate inside the thylakoid, a cone-gradient is established

  As the H+ diffuse through the ATP synthase they generate energy = Chemiosmosis

  That energy is used to attach phosphate to ADP to make ATP = phosphorylation
• Light independent Reaction (Calvin Cycle) 


  Occurs in the stroma

  Needed to convert CO2 (inorganic) into glucose (organic)

  We need to bond a number of atoms together therefore we need ATP (from light dependent)

  Some of the atoms are hydrogens therefore we need NADPH (from light dependent)
• Already in the stroma of the chloroplast is a 5c compound called RuBP.

  CO2 from the air joins the compound to make an unstable 6c compound
• Through a series of reactions that use ATP for energy and NADPH for reduction (both of which were made earlier in the light dependent reaction), the plant makes glucose (but also fructose, starch, and cellulose)
• Some of the glucose is broken back down to RuBP to keep the light independent reaction (Calvin cycle) going
• When ATP is used up, it becomes ADP + P
• When NADPH is used up, it becomes NADP+
• ADP and NADPH+ go back to the light dependent reaction so they can be made into ATP + NADPH
• Electron Transport Chain (ETC) 


  A series of reaction where e- release their energy