Photosynthesis  Defined  Defined as the process of transferring light energy into chemical energy.  Chloroplasts  Chloroplasts – part of the plant cell were photosynthesis occurs. Pg. 112 (green dots)  Thylakoid  Thylakoid – a membrane disc that hold chlorophyll in the chloroplast.  Granum  Granum – a stack of thylakoids.  Stroma  Stroma – fluid that surrounds the thylakoids in the chloroplast.

The 3 reactions of photosynthesis  1. Light absorption by chlorophyll  2. Light Reaction  3. Calvin Cycle (dark reaction)  So, what happens when light strikes a chlorophyll molecule? –1. Light is given off –2. Heat is given off –3. It is used to create energy

TTTThe light causes the chlorophyll molecules to vibrate and release electrons, which is electrical energy. Then in the second phase the electrical energy is converted to chemical energy. TTTThe transport of these electrons occurs in the photosystems of the light reaction.

 Photosystem  Photosystem II is where electrons are used as electrical energy. I is where electrons are used as chemical energy.  The  The energy produced from both photosystems is stored as ATP & NADPH Stored Energy.  Pg.  Pg. 114 & 115 Steps

Calvin Cycle  The  The stored energy in the light reaction (ATP & NADPH) is used in the Calvin cycle. Also called Dark Reaction or Light- independent Reaction.  CO 2  CO 2 is used to start the cycle. Hydrogen is then added with the help of ATP & NADPH to complete the cycle, in which sugars are produced and oxygen is released.  It  It stores sugars & starches in the leaves. –Plants –Plants stay alive for weeks without light because of the stored sugars & starches.

 Water + Carbon Dioxide  Glucose + Oxygen as a by-product –Glucose (C 6 H 12 O 6 ) is produced in the Calvin cycle (Dark Reaction). –Pg. 117  Steps  Plants are autotrophs & not mobile  Animals are heterotrophs & mobile  All of the reactions take place in the chloroplast of a plant cell (contains chlorophyll) –Calvin Cycle  stroma –Light reactions  thylakoid membrane

C 4 vs. C 3 Plants CCCC4 plants are adapted to environments with high temperatures and dry conditions. Produce more sugars. –P–P–P–Produce a 4-carbon compound of PGA They have enzymes that enable this. –E–E–E–Ex. Corn, crabgrass, buffalo grass, sugar cane –W–W–W–Warm Season Plants CCCC3 plants are adapted to cooler climates. –P–P–P–Produce a 3-carbon compound of PGA –E–E–E–Ex. Wheat, blue-grass, fescue –C–C–C–Cool Season Plants

CCCCAM plants undergo a process where their stomata are open at night & closed during the day. Why would they do this? Examples? –T–T–T–This occurs in very hot & dry climates. C Cactuses & Pineapples WWWWhere does the energy come from in plants? WWWWhat are the colors of visible light? –R–R–R–ROYGBIV WWWWhat color is most absorbed by plants?

 Plants use all the colors of the spectrum except green. It reflects green the most.  Two types of chlorophyll  A & B.  Chlorophyll A does photosynthesis, while chlorophyll B helps. Chlorophyll A prefers the red wavelength of visible light, which means most plants should grow better with that wavelength. Pg. 113  During the fall plants start to lose their chlorophyll and other accessory pigments are now displayed. –Carotenoids, xanthophylls, anthocyanins  Video - photosynthesis Video