Plants, algae, some bacteria Capture ~1% of energy from sunlight that reaches Earth Convert this to chemical energy Happens in three stages 1)Energy is captured from sunlight 2)Light energy converted to chemical energy 3)Chemical energy stored in ATP/NADPH powers formation of organic compounds

Using light, plants transform CO 2 and water into carbohydrates and release oxygen WHERE???? _____________ + ____________ __________________ + ____________ Carbon dioxide WATERSugarsOxygen 6 CO 2 _____________ + ____________ _______________ + ____________ 6 H 2 OC 6 H 12 O 6 6 O 2 →

6 CO H 2 O + light energy → C 6 H 12 O O 2

Required for photosynthesis Found in chloroplasts Chlorophyll** **Primary light-absorbing pigment in autotrophs Carotenoids Yellow, Orange, Red

Different wavelengths of light have different colors Different pigments absorb different wavelengths Color of light SEEN is the color NOT absorbed

Light Reflected Light Absorbed light Transmitted light Chloroplast

GREEN leaves have BOTH chlorophyll AND carotenoids __________________ but the huge amount of chlorophyll ______ the other colors and leaves usually look green ALL THE TIME hides

In FALL, chlorophyll production slows as the trees shut down and photosynthesis stops for winter. Then we can see the carotinoid colors that are usually hidden by chlorophyll.

red Chlorophyll a Chlorophyll b Absorption of Light by Chlorophyll a and Chlorophyll b © Pearson Education, Inc. Publishing asPearson Prentice-Hall. All rights reserved. There are two types of chlorophyll: Chlorophyll a & Chlorophyll b Chlorophyll a absorbs the _____ & ________ wavelengths best. It absorbs very little ______ light. redviolet Blue

red Chlorophyll a Chlorophyll b Absorption of Light by Chlorophyll a and Chlorophyll b © Pearson Education, Inc. Publishing asPearson Prentice-Hall. All rights reserved. NEITHER KIND OF CHLOROPHYLL IS VERY GOOD AT ABSORBING _________ LIGHT! GREEN

Light hits thylakoids Excites electrons Water molecules fall apart Oxygen is released into air Hydrogen leaves behind ion

Excited electrons travel down the electron transport chain (ETC) H + ions travel out of thylakoid Create ATP (ADP + Pi) OUTSIDE THYLAKOID: Electrons + H join NADP to make NADPH NADPH – provides electrons needed in step 3

a. Overall input: light energy, H 2 O b. Overall output: ATP, NADPH, O 2 hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/ /120072/bio13.s wf::Photosynthetic Electron Transport and ATP Synthesis

Light Independent Reactions A.K.A. Calvin Cycle or Dark Reactions In Stroma CO 2 splits C + O + H (transported by NADPH) form glucose (C 6 H 12 O 6 ) Energy from ATP is used to form new bonds

a. Overall input: CO 2, ATP, NADPH b. Overall output: glucose (after 2 full cycles)

Lack of sufficient water can cause photosynthesis to SLOW or STOP How does a cactus prevent this?

Enzymes work best at specific temperatures 0-35 °C Temp too low/high will cause photosynthesis to SLOW or STOP Conifers???

More light increases rate of photosynthesis Up to certain point, until plant reaches max rate

Compose a children’s story, song, or poem about the travels of an electron through the light reactions. Be sure to represent ALL the elements of the light reactions in your story. Illustrate a scene from your story which will best represent the activity during the light reactions. Attach your story to your illustration.

Question Research? Hypothesis Procedures Results/Data Analysis Conclusions