Important Root WordsRoot WordRoot Word MeaningMeaning

PhotoPhoto

ChloroChloro

-phyll-phyll

StomeStome

XanthoXantho

Light

Green

Leaf

Mouth

Yellow

Comprehension CheckHow many characteristics of living

things can you remember?Which characteristic is related to

this chapter?

All Organisms Need EnergyAll organisms require energy to live. There are

two main ways to obtain this necessary energy:

Cells use energy trapped in chemical bonds. When these bonds are broken, energy is released for cellular activities.

When cells use several linked chemical pathways to create the energy needed, this is called a biochemical pathway.

AUTOTROPHSAUTOTROPHSHETEROTROPHSHETEROTROPHS

Cells use EnergyCells find energy by breaking bonds in a

very special molecule called . . .ADENOSINE TRIPHOSPHATE (ATP)

ADP (adenosine diphosphate) is another important molecule involved with cellular energy

Storage and Release of Chemical EnergyEnergy is stored (in a “high energy” bond) when a

phosphate group is added to ADP

Energy is released from ATP when a phosphate group is removed (the “high energy” bond is broken)…

Note: This same system works between NADPH and NADP+

ATP: The Energy Currency

Visible LightLight travels as waves of energyReflection, Transmission, Absorption

Pigments in plants Pigments: proteins that trap light

energy from the sun, photosynthesis depends on this absorption of light to begin

Why do pigments appear as different colors?

EXAMPLES: Chlorophyll : Appears green

A: Traps Red Light B: Traps Blue Light

Accessory Pigments: Trap green/yellow Carotene: Appears orange Xanthophyll: Appears yellow

The least important color for photosynthesis?

GREEN!!

ChromatographyCan be used to separate plant

pigments based on their molecular size

Watch a video!Rf Values: Distance Pigment Moved

(mm) Distance Solvent Moved (mm)

NOTES: Rf value will always be less than 1 The higher the Rf value, the

smaller the pigment

Location of PhotosynthesisChloroplasts

Thylakoid Membranes = photosynthetic sacs (site of light absorption)

Granum = stack of thylakoids

Stroma = liquid outside/surrounds the thylakoids

http://micro.magnet.fsu.edu/cells/plants/images/chloroplast.jpg

Comprehension CheckThis weekend your teacher went to the

store and bought a new, hi-tech, green colored plant growth light. She placed a plant underneath this light inside of the fume hood and closed it tightly.

Will the plant be able to undergo photosynthesis?

Overview of PhotosynthesisDefinition: Process in which plants convert energy from the sun into stored

chemical energy (glucose).

2 main reactions in photosynthesis:1) Light Dependent Reaction 2) Light Independent (Dark) Reaction

The General Reaction for Photosynthesis:

CO2 + H20 C6H12O6 + 02

(can you balance this equation?)C6 H12 O6

CO2 H20 CO2Temperature and Light Intensity can both affect the rate of Temperature and Light Intensity can both affect the rate of photosynthesis, but it will either decrease or level off at photosynthesis, but it will either decrease or level off at some point. some point.

5 things needed for photosynthesis

WaterSunlightCarbon DioxideChlorophyll (a light

capturing pigment)Enzymes

The Light-Dependent Reactions

Light-Dependent Reactions:Location: occurs in the thylakoid membranes

Function of First Stage: Harvested light energy is converted from

sunlight to electrical energy (ETC) Uses energy from the sun to produce ATP and

NADPH needed for next reaction

Important events you should know: Chlorophyll is energized Water is split ATP and NADPH are formed Hydrogen is trapped

The Light-Dependent Reactions☼ (photons/light energy) ↓

Pigments in photosystem II and then photosystem I absorb energy ↓

Electron Transport Chain ↓ ↓

Energy splits H20 ADP + ATP* ↓ ↓ O2 2H trapped by NADP+

(forms NADPH *)

Energy used to form ATP from ADP

Both products here are used in the dark reaction

Electron Transport Chain

Process starts in a photosystem located on a thylakoid.

AbsorptionAbsorption: Photosystem II absorbs energy from photons

PassagePassage: electrons are passed to Photosystem I.

TransferTransfer: electrons are transferred along the chain generating “electricity”.

SplittingSplitting: Electricity drives the splitting of water to form H+ and free oxygen.

FormationFormation: Electrons provide energy for NADP+ to gain a H+ and form NADPH, also ATP is formed

ATP and NADPH are then used in the Dark Reaction/Calvin Cycle

Light Reaction Video

Calvin CycleCalvin Cycle (Dark/Light-Independent Reactions):

Location: takes place in the stroma

Function: Uses energy from ATP and NADPH to produce high energy carbohydrates (sugars)

Does not require light to occur (can actually occur in light or dark)

Reactions form organic compounds using energy stored from Light-dependent reactions in bonds of NADPH and ATP

Named after American scientist, Melvin Calvin, who discovered this in the early 1950’s

The Calvin Cycle/Dark Reaction

These reactions can occur with or without Light!! This begins and ends with RuBP = a 5-carbon

sugar found in chloroplasts

CO2 + RuBP + ATP* (from Light Reaction)

↓

2(PGA) + 2H* (from Light Reaction)

2(PGAL) H20 (released as a waste

product)

RuBP (80%) Glucose (20%)

CO2 given off

Calvin Cycle Animation

Calvin Cycle1.1. DiffusionDiffusion: Carbon dioxide diffuses into the stroma

2.2. CombinationCombination: CO2 binds with 5-carbon molecule called RuBP. This forms an unstable 6-carbon molecule.

3.3. SplittingSplitting: This six carbon unstable molecule splits immediately into two molecules called PGA.

4.4. ConversionConversion: PGA is changed into PGAL when:A.A. PGA receives phosphate group from an ATP molecule from

the light reactionB.B. PGA accepts Hydrogen Ions from NADPH also from the light

reaction

In summary, the Calvin Cycle fixes carbon dioxide and regenerates RuBP, produces PGA, then PGAL which may be converted to glucose.

Photosynthesis

Comprehension Check• Which parts of the process of

photosynthesis can occur in the light?• Which parts of the process can occur in

the dark?• How is the structure of the chloroplast

related to its function?• http://www.pbs.org/wgbh/nova/

methuselah/photosynthesis.html

Regulation of Photosynthesis •Stomata/Stoma: opening on underside of most leaves, entry site of carbon dioxide, release of oxygen from photosynthesis occurs here, water vapor is released here (transpiration)

•Guard Cells: specialized cells that regulate opening and closing of stomata, open and close using a H+ pump and by manipulating the turgor pressure of the cells