Photosynthesis

Photosynthesis: the process in which chloroplasts capture light energy from the sun and convert this light energy into chemical energy (stored in sugar/organic molecules)

Autotroph: “self-feed”› Ability to sustain themselves without eating

other organisms› Make organic molecules from inorganic raw

materials obtained from the environment (CO2, H2O, minerals)

› Plants, protists, and prokaryotes› Biosphere producers

Heterotroph: “other-feed”› live on compounds produced by other

organisms (unable to produce their own food)

› Biosphere consumer

Parts of the Leaf Chloroplasts are the sites of photosynthesis

› All of the green parts of the plant which contain chlorophyll-green pigment (stem, unripe fruit, LEAVES)

› Light energy is absorbed by the chlorophyll which drives the synthesis of food molecules in chloroplasts

Chloroplasts are found mainly in the mesophyll (tissues in the interior of the leaf30 to 40 chloroplasts in one mesophyll cell)

Stomata (stoma): site of gas exchange- CO2 in the leaf and O2 /water

vapour out the leaf

Roots: water is delivered to the leaves veins (xylem)and sugar is exported to the roots via the veins (phloem)

Structures of a Chloroplast Stroma: fluid within the chloroplast

› Analogous to the ______of a mitochondrion Thylakoid: flattened membranes that

contains chlorophyll Grana: stacked thylakoids

› Analogous to the _______of a mitochondrion for more surface area

Inside a chloroplast

Chemical Equation

6CO2 + 6H2O + light C6H12O6 + 6O2

Or reduced equation:CO2 + H2O + light CH2O + O2

Two Stages of Photosynthesis

1. Light reactions (photo)2. Calvin cycle (synthesis)

Light Reactions: -occurs in the thylakoid of chloroplasts-light absorbed by chlorophyll drives a

transfer of electrons and hydrogen from water to an electron acceptor NADP+

-NADP+ temporarily stores energized electrons

-water is split in the process and therefore the light reaction of photosynthesis gives of oxygen as a by product

-NADP+ gets reduced (gains 2 electrons and an hydrogen ion) by solar power and forms NADPH this generates ATP by powering a phosphate to ADP

-This synthesis of ATP ( P + ADP ) is called photophosphorylation.

** Light energy is converted to chemical energy in the form of two compounds:

1. NADPH (energized electrons)

2. ATP (energy currency of cells)

Calvin Cycle-also known as dark reactions or light

independent reactions-YET occurs in the light because it is

powered by ATP and NADPH which require light

-process involves synthesis of sugar (carbohydrate)

-occurs in the stroma(fluid)

-Carbon fixation: incorporating CO2 from the air into an organic compound

-the fixed carbon is then reduced (gains electrons) to form a carbohydrate

-fixed carbon is able to be reduced due to the NADPH reducing power and ATP produced by the light reaction