An Overview of An Overview of Photosynthesis Photosynthesis

The Big PictureThe Big PictureAll organisms need energyAll organisms need energy to carry out essential to carry out essential

functions (growth, movement, maintenance, functions (growth, movement, maintenance, repair, reproduction).repair, reproduction).

The The ultimate source of energyultimate source of energy is the is the sunsun. .

Energy flows from the Energy flows from the sun to autotrophssun to autotrophs, then to , then to organisms that eat autotrophsorganisms that eat autotrophs (heterotrophs) (heterotrophs), and , and then to organisms that feed on other organisms then to organisms that feed on other organisms (heterotrophs).(heterotrophs).

Autotrophs vs. HeterotrophsAutotrophs vs. Heterotrophs Organisms are classified by Organisms are classified by how they obtain their energyhow they obtain their energy

1.1. AutotrophsAutotrophs- organisms that make their - organisms that make their own food / use solar energy to power the own food / use solar energy to power the production of food production of food

(plants, some kinds of protists and bacteria)(plants, some kinds of protists and bacteria)

2.2. HeterotrophsHeterotrophs- organisms that must get - organisms that must get energy from food instead of directly from energy from food instead of directly from sunlight / get energy by eating other sunlight / get energy by eating other organisms or organic wastes organisms or organic wastes

(all animals, all fungi, most protists, many (all animals, all fungi, most protists, many bacteria)bacteria)

The Six KingdomsThe Six Kingdoms HeterotrophicHeterotrophic AutotrophicAutotrophic

EubacteriaEubacteria X X XX

(chemosynthesis or (chemosynthesis or photosynthesis)photosynthesis)

ArcheabacteriaArcheabacteria XX XX

(chemosynthesis)(chemosynthesis)

ProtistaProtista XX

(phagocytosis)(phagocytosis)

XX

(photosynthesis)(photosynthesis)

FungiFungi XX

(secrete digestive (secrete digestive enzymes into the enzymes into the

environment)environment)

PlantaePlantae XX

(photosynthesis)(photosynthesis)

AnimaliaAnimalia XX

(phagocytosis)(phagocytosis)

Autotrophs: Chemosynthesis vs. Autotrophs: Chemosynthesis vs.

Photosynthesis Photosynthesis PhotosynthesisPhotosynthesis- the conversion of light energy - the conversion of light energy from the sun into chemical energy in the form from the sun into chemical energy in the form of organic compounds.of organic compounds. 6CO6CO22 + 6H + 6H22O + (light energy) O + (light energy) C C66HH1212OO66 + 6O + 6O22

ChemosynthesisChemosynthesis- the use of energy stored in - the use of energy stored in inorganic molecules (COinorganic molecules (CO22) to produce ) to produce

carbohydrates (organic molecules) / chemicals carbohydrates (organic molecules) / chemicals are used as the energy source rather than are used as the energy source rather than sunlightsunlight 6CO6CO22 + 6H + 6H22O + (chemical energy-3HO + (chemical energy-3H22S) S) C C66HH1212OO66 + 3H + 3H22SOSO44

Which Organisms use Photosynthesis?Which Organisms use Photosynthesis?Which Organisms use Chemosynthesis?Which Organisms use Chemosynthesis? PhotosynthesisPhotosynthesis – – takes place on land and takes place on land and

in shallow waters where sunlight can reachin shallow waters where sunlight can reach plants and seaweedplants and seaweed

Chemosynthesis Chemosynthesis – – takes place around takes place around hydrothermal vents and methane seeps in the hydrothermal vents and methane seeps in the deep sea where there is no sunlight. It is deep sea where there is no sunlight. It is performed byperformed by bacteria bacteria living on the sea floor living on the sea floor or within animals.or within animals.

Overview of PhotosynthesisOverview of Photosynthesis 6CO6CO22 + 6H + 6H22O + (light energy) O + (light energy) C C66HH1212OO66 + 6O + 6O22

(Reactants) (Reactants) (Products) (Products)

Autotrophs use Autotrophs use photosynthesisphotosynthesis to produce organic compounds from carbon to produce organic compounds from carbon

dioxide and water.dioxide and water.

The Two Stages of Photosynthesis:The Two Stages of Photosynthesis:

Light Reactions Light Reactions (Light Dependent Reactions)(Light Dependent Reactions)

Calvin Cycle Calvin Cycle (Light Independent Reactions)(Light Independent Reactions)

Stage 1: Light ReactionsStage 1: Light Reactions Series of steps in which:Series of steps in which:

Light energyLight energy is absorbed from the sun and converted is absorbed from the sun and converted into into chemical energy chemical energy (ATP and NADPH)(ATP and NADPH)

Water (HWater (H22O)O) is the first reactant used, and is the first reactant used, and OO22 is the first is the first

byproduct produced.byproduct produced. Chemical energy is temporarily stored as Chemical energy is temporarily stored as ATPATP and and

NADPHNADPH (energy carrier molecule) (energy carrier molecule)

Stage 2: Calvin CycleStage 2: Calvin Cycle Series of steps in which:Series of steps in which:

Carbon Dioxide (COCarbon Dioxide (CO22)) is the second reactant used, along is the second reactant used, along

with the chemical energy from the light reactions (stored with the chemical energy from the light reactions (stored in ATP and NADPH) in ATP and NADPH)

Organic compounds (Organic compounds (glucose – Cglucose – C66HH1212OO66) are formed.) are formed.

Structure and Structure and Function of a LeafFunction of a Leaf

Structure and FunctionStructure and Function1.1. Upper Epidermis-Upper Epidermis- structure, support, protection structure, support, protection2.2. CuticleCuticle- waxy coating, helps prevent water loss- waxy coating, helps prevent water loss3.3. Palisades Layer-Palisades Layer- wherewhere majority of photosynthesis takes place majority of photosynthesis takes place4.4. ChloroplastChloroplast- site of photosynthesis- site of photosynthesis5.5. PhloemPhloem- transports sugars in any direction- transports sugars in any direction6.6. XylemXylem- transports water upward only (roots - transports water upward only (roots shoots) shoots)7.7. Guard CellsGuard Cells- specialized cells that border a stoma and - specialized cells that border a stoma and

regulate gas exchange regulate gas exchange8.8. StomataStomata- gas exchange- gas exchange9.9. VeinVein- transport tissue (vein= xylem + phloem)- transport tissue (vein= xylem + phloem)10.10. Lower EpidermisLower Epidermis- structure, support, protection- structure, support, protection11.11. Spongy LayerSpongy Layer- photosynthesis, air exchange- photosynthesis, air exchange12.12. MesophyllMesophyll- air exchange and photosynthesis (3 +11)- air exchange and photosynthesis (3 +11)

Stomata – please sketch on your labStomata – please sketch on your labGuard Cells

Stomata