Bellwork: What do you know about photosynthesis? Photo-synthesis means "putting together with light." 6CO2 + 6H2O (+ light energy) -----> C6H12O6 + 6O2 Respiration C6H12O6 + 6O > 6CO2 + 6H2O + Energy (ATP)

Photosynthesis-starts the ecological food webs!

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.

Plant leaves have many types of cells!

Chloroplasts make the sugars!

Plants Leaves are green because they contain the pigment: chlorophyll Why do leaves have a broad surface area? "Thanks for the Glucose!"

PHOTOSYNTHESIS Why do we see green? Green color from white light reflected NOT absorbed Chloroplast: organelle responsible for photosynthesis Chlorophyll: located within Chloroplast Green pigment

Plant Cells

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

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Extra Tidbits  Important part of Oxygen- Carbon Dioxide Cycle. –pumps out oxygen –Removes CO 2 from atmosphere  ↑ levels of CO 2 linked with ↑ global temp (think "Global Warming").

Chloroplasts ½ of the chemistry occurs in a liquid inside the chloroplasts called STROMA ½ of photosynthesis occurs in stacks of membranes inside the chloroplast called GRANA.

Chlorophyll  Green pigment, which absorbs sunlight.  2 types of chlorophyll –chlorophyll a –chlorophyll b  Chlorophyll a is the main, b is an accessory

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

Photosynthesis

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.

Check it! Photosynthesis Rap

EQUATION FOR PHOTOSYNTHESIS 6CO 2 + 6H 2 O + ENERGY C 6 H 12 O 6 + 6O 2 CARBON DIOXIDE WATER GLUCOSE OXYGEN

PHOTOSYNTHESIS What affects photosynthesis? Light intensity: as light increases, rate of photosynthesis _____________________

PHOTOSYNTHESIS What affects photosynthesis? Carbon Dioxide: As CO 2 increases, rate of photosynthesis _________________

PHOTOSYNTHESIS What affects photosynthesis? Temperature: Temperature Low = Rate of photosynthesis low Temperature Increases = Rate of photosynthesis increases If temperature too hot, rate drops

ChlorophyllChlorophyll: A Light Absorbing Pigment Chlorophyll The Solar Panel Chemical!

Photosynthesis Glucose provides the energy and carbon needed to make other plant materials like wax and proteins.

Oxygen and Sugar!

In plants and simple animals, waste products are removed by diffusion. Plants, for example, excrete O 2, a product of photosynthesis.

PHOTOSYNTHESIS How did we get O 2 as a byproduct?! Photolysis: replaces lost electrons by splitting water

Check it! 1.The process that uses the sun’s energy to make simple sugars is _____________. A.Cellular respiration B.Glycolysis C.Photosynthesis D.Photolysis

Check it! 2.The function accomplished by the light- dependent reactions is ______________. A.Energy storage B.Sugar production C.Carbon fixation D.Conversion of sugar