photosynthesis

• what is photosynthesis

  process by which plants convert light energy into chem energy
• what is the basic reaction for photosynthesis

  6CO2 + 6H2O → C6H12O6 + 6O2

  sunlight + chlorophyll on arrow
• what is ATP

  "energy currency" for the cell - provides energy to cellular reactions 
• what is NADPH

  electron + proton carrier - collect + shuttles them at high energy from reaction to reaction around the cell
• what are the inputs, outputs, location and purpose for the light dependent reaction

  PURPOSE: convert light energy from the sun to chem energy (in form of high energy coenzymes) - ATP, NADPH

  LOCATION: thylakoid membrane in chloroplast

  H2O → O2

  18 ADP + Pi → 18 ATP

  12 NADP+ → 12 NADPH
• what are the inputs, outputs, location and purpose for the light independent reaction

  PURPOSE: fix carbon to become an organic compound (glucose) which can be used as chemical energy source

  LOCATION: stroma

  6 CO2 → C6H12O6 ; 6 H2O

  18 ATP→ 18 ADP + Pi

  12 NADPH → 12 NADP+
• what is the difference b/w light independent stage and the calvin cycle

  calvin cycle doesn't have glucose as final product, but light independent stage DOES
• what is rubisco

  an enzyme involved w first step of the calvin cycle (carbon fixation) + intiates the calvin cycle 

  bind to CO2 = photosythesis (good) 

  bind to O2 = photorespiration (bad) - wasteful energy, no glucose produced
• factors that affect affinity of rubisco

  • substrate concentration --> more substrate, more likely to bind - closed stomata less CO2 enters = more O2 build up 
  • temperature - higher temp = increases O2 binding to rubisco
• what is the calvin cycle?

  cycle of reactions that convert CO2 to glucose 

  
  

  1. carbon fixation

  3CO2 + 3RuBP --> 6 3-PGA w help of rubisco

  
  

  2. reduction

  6 3-PGA --> 6 G3P

  1G3P released to form GLUCOSE w another G3P molecule

  
  

  3. RuBP regeneration

  5G3P --> 3RuBP 

  cycle continues
• what is C3 photosynthesis

  no adaptations

  • normal light dependent stage
  • normal light independent stage + calvin cycle
• what is C4 photosynthesis

  • adapted for hot + humid conditions
  • normal light dependent stage 
  • carbon fixation + rest of calvin cycle occurs in 2 different cells
  • light dependent + carbon fixation = mesophyll cells
  • reduction + regeneration = bundle-sheath cells 
• what is the process of C4 photosynthesis

  1. light dependent stage
  2. mesophyll cell - high O2 concentration

  CO2 enters + fixed by PEP carboxylase → oxaloacetate (4-carbon)→ malate → transport to bundle-sheath cell

  
  

  3. bundle-sheath cell - relative low O2 concentration

  
  

  malate →  CO2 + pyruvate 

  CO2 binds to rubisco = initiate calvin cycle

  pyruvate →  transport to mesophyll cell using ATP (regenerate PEP) 
• what is CAM photosynthesis

  • adapted to hot + dry conditions --> cacti, pineapple
  • normal light dependent stage
  • light independent stage separated by time
  • light dependent + carbon fixation = day
  • reduction + regeneration = night
• what is the process of CAM photosynthesis

  1. light dependent stage
  2. night - open stomata

  CO2 enters +fixed by PEP carboxylase → oxaloacetate(4-carbon)→ malate → transport to vacuole

  
  

  3. day - close stomata

  
  

  malate transport out vacuole→  CO2 + pyruvate 

  CO2 binds to rubisco = initiate calvin cycle

  pyruvate →  transport to mesophyll cell using ATP (regenerate PEP)