Photosynthesis

ATP

• Calvin cycle

  • ATP is broken down to ADP + P in order to do work

ATP synthase

• allows hydrogen ions to move from high to low concentration

• Hydrogen moving through causes ATP synthase to spin and create ATP (energy)

  
  

ADP

• Forms from the breaking down of ATP in calvin cycle

• ATP broken down into ADP + P after donating energy to chem rxns in calvin cycle

NADP+

• accepts electrons after they get excited by light again in Photosystem I

• Accepts hydrogen also and becomes NADPH

  • electron carrier

    • carries electrons & hydrogens to the calvin cycle

      
      

Calvin Cycle

1. Carbon fixation

   • Carbon from the air enters the Calvin Cycle

   • ”Fixed” into a usable form by RuBP

   • Inorganic → Organic

2. Reduction

   • powered by ATP energy

   • Creation of a triose phosphate (3 C compound)

   • ½ of glucose

   • 2 turns of the Calvin Cycle to get 1 glucose

3. Regeneration

   • Recreate RuBP which is the CO2 acceptor

   • ADP and NADP+ return to thylakoid

Chemosynthesis

• process by which certain bacteria & other microorganisms create energy by using chemicals instead of sunlight

Chlorophyll

• Green pigment in plants, essential for photosynthesis, capturing sunlight for energy conversion.

Electron transport chain (ETC)

Light-dependent reactions

• In the thylakoid

• light absorbed by pigments

• Reactant: water

  • From the soil

    • Root → shoot

    • xylem carries water

    • osmosis

      • brings water to the cell & stomata

    • Light-dependent reaction occurs

• Product: ATP & NADPH

• Byproduct: Oxygen

Light-independent reactions

• Powered by light-dependent reaction

• occurs at the Stroma

• CO2 → fixed into glucose

  • Reactant: CO2

    • From the air

    • enters stomata

    • Calvin cycle occurs

  • Product: TP → glucose

  • Recycled: ADP + P & NADPH+

NADP reductase

• enzyme that helps with the formation of NADPH

  • NADPH is an energy-carrying molecule.

NADPH

• Calvin Cycle

• Specific enzyme for photosynthesis

  • NADPH → broken down into NADP + H+ + e

  • NADP → final electron acceptor in the ETC

• provides electrons & hydrogens needed to build sugar

Photosynthesis

• The process where light energy, water, and carbon dioxide create glucose for chemical energy with the release of oxygen.

Photosystems

• clusters of proteins and pigments (chlorophyll) organized into complexes in chloroplasts or bacterial membranes

• Pigments absorb light energy

• Electrons get excited and enter ETC

• Photolysis

  • Splitting of water

  • Oxygen leaves through stomata

  • Hydrogen ions build up in thylakoid

  • Electrons move to photosystem II to replace e- that entered the electron transport chain

Thylakoid 

Regeneration of ATP & NADPH

1. Electrons move through the electron transport chain

2. Hydrogen builds up in the thylakoid

3. H moves through chemiosmosis through an enzyme that makes ATP (ATP synthase)

4. NADP+ is an electron acceptor

5. NADP+ joins with the electron and hydrogen to make NADPH (NADP+ reductase)

Pigments

• Chlorophyll a & b

  • green pigments

  • most common

• Carotenoids

  • orange

• Xanthophyll

  • yellow

Absorption Spectrum

• The wavelengths of light absorbed by each pigment

• Chlorophyll

  • absorbs light most strongly in the blue, followed by the red portion

  • reflects light most strongly in the green portion

Factors that affect photosynthesis

• Sunlight

  • Amount of sunlight

    • seasons

    • latitude

  • Color of the light

• Temperature

  • Warmer temperature increases the rate of photosynthesis

  • excessive heat causes water loss

    • desert/savannah

• Carbon dioxide concentration

  • Increased Concentration - Increased Rate:

Stroma

• Fluid around the thylakoid where the Calvin cycle takes place