Presentation on theme: "Bellwork: What do you know about photosynthesis? Photo-synthesis means "putting together with light." 6CO2 + 6H2O (+ light energy) -----> C6H12O6 + 6O2."— Presentation transcript:
Bellwork: What do you know about photosynthesis? Photo-synthesis means "putting together with light." 6CO2 + 6H2O (+ light energy) -----> C6H12O6 + 6O2 Respiration C6H12O6 + 6O2 -----> 6CO2 + 6H2O + Energy (ATP)
What is photosynthesis? A chemical reaction in which light energy is converted to chemical energy in the form of glucose. It is how the energy in sunlight becomes usable to living things.
Why is it so important? Two big reasons: 1. One product is glucose (sugar), which provides the basis for most food chains. 2. The second product is oxygen which is needed by aerobic organisms (require oxygen) for survival.
Photosynthesis Carbon dioxide + water glucose + oxygen sunlight absorbed by chlorophyll 6CO 2 + 6H 2 O + energy C 6 H 12 O 6 + 6O 2 As can be seen from the equation for photosynthesis, the wood, bark, and root came from water and carbon dioxide.
Where does photosynthesis occur? Most photosynthesis occurs in the oceans, the oceans occupy (70%) of the earth's surface!
In terms of organisms, photosynthesis occurs in autotrophs that contain the green pigment chlorophyll. Review: What is an autotroph?
Multicellular level: photosynthesis occurs in the leaves of plants. Cellular level: the reactions for photosynthesis occur in the chloroplasts of eukaryotes and in the cytoplasm of prokaryotes.
The photograph below is an elodea leaf X 400. Individual cells are clearly visible. The tiny green structures within the cells are chloroplasts this is where photosynthesis happens.
What raw materials are needed? Chlorophyll Sunlight Water Carbon dioxide
Biochemical Pathway Photosynthesis is a series of two reactions The products from the 1 st rxn are used in the 2 nd
PHOTOSYNTHESIS 2 Phases Light-dependent reaction Light-independent reaction Light-dependent: converts light energy into chemical energy; produces ATP molecules to be used to fuel light-independent reaction Light-independent: uses ATP produced to make simple sugars.
Summary of Photosynthesis carbon dioxide + water + light energy -- -> glucose + oxygen + water As a chemical formula: CO 2 + H 2 O + light energy ---> C 6 H 12 O 6 + O 2 + H 2 O
Chemical Reaction Occurs in two phases. Capture Energy #1 is called the "light reactions". It requires light! Convert Energy to Food #2 is called "carbon fixation" or the "dark reactions". Aka Calvin Cycle It does not require light.Calvin Cycle Start with CO2 End with Glucose
EQUATION FOR PHOTOSYNTHESIS 6CO 2 + 6H 2 O + ENERGY C 6 H 12 O 6 + 6O 2 CARBON DIOXIDE WATER GLUCOSE OXYGEN
Back to the Chloroplast The light reactions occur in the grana, which contain the chlorophyll for absorbing light. The dark reactions occur in the stroma.
Detailed Light Reactions The light reactions use light & water, & produce the oxygen "waste product". The light energy is used to split the water molecule (photolysis), which produces e-’s. H+ & O- ions. The oxygen is released from the plant into the air.
ATP & NADPH 2 are energy molecules. They will be used up during the dark reactions, as will the H+ ions.
Electron Transport CONVERTS to useable Energy 1. Light excites the electrons 2. E-’s leave chlorophyll a and go to the primary electron acceptor (PEA) (in thylakoid membrane)
Sun Chlorophyll passes energy down through the electron transport chain. for the use in light-independent reactions bondsP to ADP forming ATP oxygen released splits H 2 O H+H+ NADP + NADPH Light energy transfers to chlorophyll. Energized electrons provide energy that At each step along the transport chain, the electrons lose energy.
3. PEA then donates the e’s to other molecules which pass them on over and over. (electron transport chain) 4. E’s join with a proton and NADP+ which forms NADPH
Replacing the Electrons E-’s are taken from the chlorophyll to pass down the ETC. They must be replaced to be passed down again. E-’s accumulated during photolysis are given to the chlorophyll.