plants and some other types of organisms are able to use light energy from the sun to produce food. ...
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CHAPTER 8: PHOTOSYNTHESIS
AUTOTROPHS
Plants and some other types of organisms are able to use light energy from the sun to produce food.
Contain chlorophyll, a pigment that captures sunlight.
HETEROTROPHS
Organisms that cannot make their own food.
Cannot use sun’s energy directly.
ENERGY
Comes in many forms including light, heat, and electricity.
Can be changed from one form to another.
Can be stored in chemical compounds.
Candles release energy as HEAT & LIGHT
ATP – CELLULAR ENERGY
Adenosine triphosphate Contains two, high-energy phosphate
bonds Also contains the nitrogen base
adenine & a ribose sugar
ENERGY
Energy is stored in the bond between the 2nd and 3rd phosphates.
ADP
Adenosine Diphosphate ATP releases energy, a free phosphate, &
ADP when cells take energy from ATP
USING ENERGY IN ATP
ATP only provides energy for a few seconds. It is constantly being used and remade by
cells. Provides energy for all cell’s activities:
Active Transport Movement Photosynthesis Protein Synthesis Cellular Respiration Many more!
STORING AND RELEASING ENERGY
Adding A Phosphate Group To ADP stores Energy in ATP
Removing A Phosphate Group From ATP Releases Energy & forms ADP
Loose
Gain
GLUCOSE Glucose is a
monosaccharide C6H12O6
One Molecule of glucose Stores 90 Times More Chemical Energy Than One Molecule of ATP
PHOTOSYNTHESIS In words:
Involves the use Of light energy to convert Water (H20) and Carbon Dioxide (CO2) into Oxygen (O2) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches.
THE PHOTOSYNTHESIS EQUATION
6CO2 + 6 H2O + energy C6H12O6 +
6O2
Carbon Dioxide + Water + Sunlight Glucose + Oxygen
THE PHOTOSYNTHESIS EQUATION
PIGMENTS
• In addition to water, carbon dioxide, and light energy, photosynthesis requires Pigments
• Chlorophyll is the primary light-absorbing pigment in autotrophs
• Chlorophyll is found inside chloroplasts
LIGHT AND PIGMENTS Energy From The Sun
Enters Earth’s Biosphere As Photons
Photon = Light Energy Unit
Light Contains A Mixture Of Wavelengths
Different Wavelengths Have Different Colors
LIGHT AND PIGMENTS Different pigments absorb different
wavelengths of light Photons of light “excite” electrons in
the plant’s pigments Excited electrons carry the absorbed
energy The main pigments found in plants is
chlorophyll. Chlorophyll is found in
chloroplasts.
CHLOROPHYLLChlorophyll absorbs light well in the blue-violet
and red regions of the visible spectrum.
INSIDE A CHLOROPLAST Contain saclike photosynthetic membranes
called thylakoids. Thylakoids are arranged in stacks called
grana (singular: granum). Contain clusters of chlorophyll and other
pigments as well as proteins known as photosystems that capture sunlight energy.
Singlethylakoid
INSIDE A CHLOROPLAST Gel-like material surrounding the grana
= stroma.
ELECTRON CARRIERS When electrons in chlorophyll absorb
sunlight, the electrons gain A LOT of energy.
Chloroplasts use electron carriers to transfer these electrons from chlorophyll to other molecules.
NADP+
One electron carrier is NADP+.
It accepts and holds 2 high-energy electrons along with a hydrogen ion (H+).
LIGHT-DEPENDENT REACTIONS Part 1 of Photosynthesis Occurs across thylakoid membranes. Uses light energy. Produce oxygen from water. Convert ADP to ATP and NADP+ to
NADPH.
LIGHT-DEPENDENT REACTIONS
LIGHT-DEPENDENT REACTIONS SUMMARY Reactants
Water (H2O) Sunlight energy
Products ATP NADPH
THE CALVIN CYCLE Also known as:
Light-Independent Reactions
Occur in stroma Uses ATP and
NADPH from the Light-Dependent Reactions to form high-energy sugars.
THE CALVIN CYCLE Six CO2 molecules
enter the cycle. Bonds in the ATP
and NADPH molecules are broken to release the stored energy.
This energy is used to turn the CO2
molecules into a 6-carbon sugar (glucose).
CALVIN CYCLE SUMMARY Reactants
CO2
ATP
NADPH Products
C6H12O6 (high-energy sugar)
ADP NADP+
PHOTOSYNTHESIS SUMMARY
Reactants Products
•H2O•Sunlight
•ATP + O2
•NADPH
Reactants Products
•CO2 (from environment)•ATP•NADPH
•C6H12O6
• ADP•NADP+
Light-Dependent Reactions
Calvin Cycle/Light-Independent Reactions
PHOTOSYNTHESIS SUMMARY
FACTORS AFFECTING RATE OF PHOTOSYNTHESIS
Temperature Amount of
Water Light
availability