Plants, algae, some bacteriaCapture ~1% of energy from sunlight that reaches Earth

Convert this to chemical energyHappens in three stages1) Energy is captured from sunlight2) Light energy converted to chemical energy3) Chemical energy stored in ATP/NADPH powers

formation of organic compounds

Using light, plants transform CO2 and water into carbohydrates and release oxygenWHERE????

_____________ + ____________ __________________ + ____________

Carbondioxide WATER Sugars Oxygen

6 CO2_____________ + ____________ _______________ + ____________6 H2O C6H12O6 6 O2→

6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2

Required for photosynthesisFound in chloroplastsChlorophyll**

**Primary light-absorbing pigment in autotrophsCarotenoids

Yellow, Orange, Red

Different wavelengths of light have different colorsDifferent pigments absorb different wavelengthsColor of light SEEN is the color NOT absorbed

LightReflected

Light

Absorbedlight

Transmittedlight

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 thecarotinoid colors that are usually hidden by chlorophyll.

red

Chlorophyll a

Chlorophyll b

Absorption of Light byChlorophyll 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.

red violet

Blue

red

Chlorophyll a

Chlorophyll b

Absorption of Light byChlorophyll 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

http://www.youtube.com/watch?v=C1_uez5WX1o

Light hits thylakoidsExcites electronsWater molecules fall apart

Oxygen is released into airHydrogen 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 NADPHNADPH – provides electrons needed in step 3

a. Overall input:

light energy, H2O b. Overall output:

ATP, NADPH, O2

http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120072/bio13.swf::Photosynthetic Electron Transport and ATP Synthesis

Light Independent ReactionsA.K.A. Calvin Cycle or Dark Reactions

In StromaCO2 splitsC + O + H (transported by NADPH) form glucose (C6H12O6)Energy from ATP is used to form new bonds

a. Overall input:

CO2, 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.

QuestionResearch?HypothesisProcedures Results/Data AnalysisConclusions