Photosynthesis Chapter 3.1

Capturing the Energy of Life All organisms require energy Autotrophs obtain energy directly from the sun and store it as glucose during a process called photosynthesis 6CO2 + 6H2O    6O2 + C6H12O6 sunlight

Energy for Life Processes Autotrophs (producers) convert sunlight, CO2, and H2O into glucose (their food) Plants, algae, blue-green bacteria Heterotrophs obtain necessary carbon by eating autotrophs Animals, fungi, protists

Biochemical Pathways Photosynthesis is a biochemical pathways Series of reactions where the product of one reaction is the reactant of the next

Light Absorption in Chloroplasts Chloroplasts absorb light energy from the sun during the light dependent reactions Chloroplasts = inner membrane is folded into disc-shaped sacs called thylakoids Thylakoids = contain chlorophyll and are in stacks called granum Granum = surrounded by a gel-like material called stroma

Chloroplast

Pigments When all colors are absorbed, the object appears black When all colors are reflected, the object appears white If only one color is reflected (green), the object appears that color (ex: Chlorophyll)

Photosystems Photosynthesis involves many steps Two Photosystems: Light dependent Light independent (Calvin Cycle)

Light Dependent Water is split, giving off oxygen H2O   O2  Water is split, giving off oxygen Light is absorbed by chlorophyll “Excites" electrons and makes ATP (energy) Takes place in the thylakoids

Light Independent (Calvin Cycle) CO2  C6H12O6 Carbon dioxide is split, providing carbon to make glucose The ultimate product is glucose. Depends on products from the light reactions Takes place in the stroma

Transportation of Nutrients Xylem Moves water from the roots up the stem to the leaves Phloem Moves glucose from the leaves down the stem to the roots