Continual input of solar energy into Earth’s atmosphere Almost 1/3 is reflected back into space Of the energy that reaches Earth’s surface, about 1% is intercepted by photoautotrophs (organisms that capture light energy to make food) This means that only 10% of the energy is passed to each trophic level
Light Sunlight is perceived as “white” light Actually is a mixture of wavelengths Light absorbing pigments (CHLOROPHYLL) gather the sun’s energy
Absorption of Light by Chlorophyll a and Chlorophyll b Chlorophyll absorbs light very well in the blue and red regions of the visible spectrum. It does not absorb green which is why the plant is green. –Light AbsorptionLight Absorption –http://mc2.cchem.berkeley.edu/Java/
Light-catching part of molecule often has alternating single and double bonds These bonds contain electrons that are capable of being moved to higher energy levels by absorbing light
Main pigments in most photoautotrophs Wavelength absorption (%) Wavelength (nanometers) chlorophyll b chlorophyll a
Chlorophylls a and b- reflect green Carotenoids-reflect red, yellow, orange Carotenes - pure hydrocarbons Xanthophylls - contain oxygen Anthocyanins-reflects red to purple (flowers) Phycobilins-reflects red to purple (flowers)
Bacteria Pigments in plasma membranes Plants Pigments embedded in thylakoid membrane system Pigments and proteins organized into photosystems Photosystems located next to electron transport systems
Photosynthesis Equation: light 6CO 2 +6H 2 O C 6 H 12 O 6 +6O 2
Energy also comes in chemical compounds. Adenosine Triphosphate – ATP Consists of a nitrogen-containing compound (adenine), a 5-C sugar (ribose), & THREE phosphate groups Adenosine Diphosphate – ADP Consists of a nitrogen-containing compound (adenine), a 5-C sugar (ribose), & TWO phosphate groups
Stores Energy for all types of cells. Organelles can move throughout cell. Active Transport Sodium-Potassium pump
ATP only stores small quantities of energy. Only allows a few seconds of activity. Glucose stores 90 times as much energy. Possible Solution??? Store glucose and use it to make ATP.
Another energy carrying molecule NADP + + H + + 2e - NADPH Energy carrier energystored energy NADPH NADP + + H + + 2e - Stored energy Energy carrier released energy
LIGHT Water O2O2 Sugars CO 2 Chloroplast Light- Dependent Reactions Calvin Cycle NADPH ATP ADP + P NADP +
Require light Produce oxygen gas Convert ADP and NADP+ into energy carriers ATP and NADPH
It is strongly recommended that you look at your book diagrams before the test and read your notes at the same time!
When a pigment molecule absorbs a photon, one of the pigment’s electrons jumps to an energy level farther from the nucleus, making it have an ‘excited’ state Both photosystems capture solar power
Chlorophyll a is called P680 Chlorophyll a is called P700 You don’t need to know this, but it has to do with the wavelengths of the colors they absorb. 680 nm is the red wavelength and 700 nm is the far red wavelength Extra Info…
Photosystem II Water molecules are split, allows ADP to become ATP again
Light energy is converted to chemical energy of ATP and NADPH Electrons removed from water pass from photosystem II to photosystem I to NADP+, providing energy for the synthesis of ATP
Plants use energy that ATP and NADPH contain to build high-energy compounds that can be stored for a long time Produces high-energy sugars Light-independent reaction Sugar factory within the chloroplast
1. Carbon fixation—enzyme called rubisco combines with Carbon Dioxide, and splits 2. Reduction—two chemical reactions consume energy from ATP and oxidize NADPH. Produces energy rich three carbon sugars 3. G3P released—Net product of photosynthesis— used to make glucose 4. Regeneration of RuBP—ATP rearranges G3P to form more RuBP for step 1 to repeat FOR ONE G3P MOLECULE, THE CALVIN CYCLE CONSUMES NINE ATP AND SIX NADPH, PROVIDED BY THE LIGHT REACTIONS. IT TURNS SIX TIMES TO MAKE ONE GLUCOSE MOLECULE.
Water Shortage of water would slow/stop photosynthesis Temperature Enzymes are necessary Ideal temps (0-35 degrees C) Light intensity
Oxygen Carbon Dioxide and Moderation of Global Warming Other?