1. Photosynthesis includes light reactions and dark reactions
1. light reactions: The light reactions require light. Energy of light is converted to chemical energy and conserved as
“high energy” compound ATP
reducing power of NADPH
2.dark reactions : The light-independent reactions occur either in the light or in the dark.
NADPH and ATP produced by the light reactions are used in the reductive synthesis of carbohydrate from CO2 and water

4. Sun light
Synthesis of Glucose
The “goal” of photosynthesis is to synthesize the carbohydrate “glucose”.
Carbon dioxide is reduced to glucose (see equation below).
The electrons needed for this reduction come from water.
The energy needed for this reduction comes from light (ATP, NADPH).
The equation is:
Energy + 6CO2 + 6H2O  C6H12O6 + 6O2

5. photosystem
Two kinds of photosystems are involved in photosynthesis in plants.
Photosystem I (PSI) is defined as containing reaction center chlorophylls with maximal light absorption at 700 nm.
Photosystem II (PSII) absorbs light about 680 nm.
both of the two photosystems are pigment/protein complexes that are located in thylakoids

6. The roles of photosystem I (PS I) and photosystem II (PS II)
PS I provides reducing power NADPH
PS II uses light energy to drive two chemical reactions - the split of water producing O2 and releasing electrons into an electron transport chain (Photosynthetic Electron Transport).

7. Types of photosynthesisC3
The majority of plants C4
CO2 temporarily stored as 4-C organic acids resulting in more efficient C exchange rate
Advantage in high light, high temperature, low CO2
Many grasses and crops (e.g., corn, sorghum, millet, sugar cane)
CAM
Stomata open during night
Advantage in arid climates
Many succulents (e.g., cacti, euphorbs, bromeliades, agaves)

8. Cellular Respiration
Breakdown of glucose begins in the cytoplasm: the liquid matrix inside the cell
At this point life diverges into two forms and two pathways
Anaerobic cellular respiration (aka fermentation)
Aerobic cellular respiration

9. Cellular Respiration Reactions
Glycolysis
Series of reactions which break the 6-carbon glucose molecule down into two 3-carbon molecules called pyruvate
Process is an ancient one-all organisms from simple bacteria to humans perform it the same way
Yields 2 ATP molecules for every one glucose molecule broken down
Yields 2 NADH per glucose molecule

11. Anaerobic Cellular Respiration
Some organisms thrive in environments with little or no oxygen
Marshes, bogs, gut of animals, sewage treatment ponds
No oxygen used= ‘an’aerobic
Results in no more ATP, final steps in these pathways serve ONLY to regenerate NAD+ so it can return to pick up more electrons and hydrogens in glycolysis.
End products such as ethanol and CO2 (single cell fungi (yeast) in beer/bread) or lactic acid (muscle cells)

13. Aerobic Cellular Respiration
Oxygen required=aerobic
2 more sets of reactions which occur in a specialized structure within the cell called the mitochondria
1. Kreb’s Cycle
2. Electron Transport Chain

14. Kreb’s Cycle Completes the breakdown of glucose
Takes the pyruvate (3-carbons) and breaks it down, the carbon and oxygen atoms end up in CO2 and H2O
Hydrogens and electrons are stripped and loaded onto NAD+ and FAD to produce NADH and FADH2
Production of only 2 more ATP but loads up the coenzymes with H+ and electrons which move to the 3rd stage

16. CO2 effects on photosynthesis
C4 > C3 at low CO2
But, C3 > C4 at high CO2
*At high CO2, C3 more efficient than C4 at all temps. (photosynthesis only, not other processes)

17. Photosynthetic N-use efficiency
C4 plants need (have) less leaf N than C3
Photosynthesis higher per unit N in C4
Humans are increasing global N, which benefits C3 more than C4
Increasing CO2 decreases leaf N content, more in C3 than C4

18. Photosynthetic water-use efficiency
C4 plants use less water than C3
(cause stomates open less)
Water availability may increase or decrease in the future.