1. Unit 2: Metabolic Processes Photosynthetic Organisms
SBI4U – Ms. Richardson

2. Photosynthesis Purpose: Location: General Equation
To synthesize carbohydrates (ie. glucose) using the Sun’s energy
Location:
Chloroplast
General Equation
6CO2 + 6H2O  C6H12O6 + 6O2
Visible Light
Chlorophyll

3. Photosynthetic Organisms
Includes plants, algae, some protists and cyanobacteria
All contain chlorophyll
green-coloured pigment
Absorbs light energy
Several types:
Chlorophyll a (blue-green), contains methyl group
Chlorophyll b (yellow-green), contains aldehyde group

4. Photosynthetic Organisms
Chlorophyll is composed of a porphyrin ring attached to hydrocarbon chain
Porphyrin contains magnesium atom
Delocalized electrons within porphyrin absorb light energy
Hydrocarbon tail (phytol tail) anchors the molecule within the cell membrane

5. Prokaryotic Autotrophs Cyanobacteria
(blue-green algae)
Unicellular
First photosynthetic organisms
Largest group of photosynthesizing prokaryotes
Blooms often develop in water that has high nitrate and phosphate levels

6. Eukaryotic Autotrophs: Algae, Protists & Plants
Chlorophyll contained within chloroplasts
Chloroplasts are only located in leaves, stems, and unripened fruit

7. Leaves Function: Structure: photosynthesis
maximizes surface area exposed to light
limits distance for gases to travel to reach chloroplast

8. Leaves

9. Transpiration
Loss of water vapour in plants, primarily through stomata
Assists photosynthesis:
Transpiration pull
Evaporative cooling

10. Stomata Controls gas exchange
Guard cells swell when K+ ions and water move into guard cells
Stomata close (night)
When K+ ions and water move out of guard cells, they become flaccid
Stomata open (day)
CO2 absorbed

11. Chloroplasts Site of photosynthesis
Occurs mainly in stroma and thylakoid membrane
Contain their own DNA and ribosomes
May contain starch an lipids