Module 6, lesson 1 photosynthesis

Photosynthesis

(Life from )

6H2O + 6CO2 ----> C6H12O6+ 6O2

Light

A little backgroundOrganisms

autotrophs heterotrophs

Make own food Obtain food from others

• Grass Caterpillar Bird• Autotroph Heterotroph Heterotroph

• All energy originates with Autotrophs

The fuel of living things

• ATP- Adenosine triphosphate– Consists of

• Adenine• 5-carbon sugar called ribose• Three phosphate groups

– Key to ATP’s ability to release energy

Adenine

Ribose

P P P

ADP• ADP is a cousin of ATP

– Main differences• ADP has 2 phosphates ATP has

3• ADP has less energy then ATP

This is whereThe bond breaksTo turn ATP intoADP

ADP

The photosynthesis equation

• The process by which light energy is converted into chemical energy and stored in organic compounds

• Referred to as biochemical pathway

6H2O + 6CO2 energy C6H12O6 + 6O2

Reactants Products

Energy needs of Life

• All life needs a constant input of energy– Heterotrophs (animals, fungi, most bacteria)

• get their energy from “eating others”• consumers of other organisms• consume organic molecules

– Autotrophs (plants, some bacteria)• get their energy from “self”• use sunlight energy to synthesize organic

molecules

• We will be looking at how autotrophs and how they synthesize these organic molecules through photosynthesis

CO2

Where does photosynthesis occur? In the chloroplasts!

absorbsunlight & CO2

makeenergy & sugar

Light: absorption spectrum

• Light reaction can perform work with wavelengths of light that are absorbed– chlorophyll a — the dominant pigment — absorbs best in

red & blue wavelengths & least in green– other pigments with different structures have different

absorption spectra

Chloroplasts

• Green because absorb light wavelengths in red & blue and reflect green back out

THAT IS WHY PLANTS LOOK GREEN TO US! WE SEE WHAT IS RELFECTED.

Photosynthesis: Overall Equation

This is the equation you are used to seeing, but this is not the whole story…

+ water + energy glucose + oxygencarbondioxide

6CO2 6H2O C6H12O6 6O2light

energy+ ++

Photosynthesis• Actually two separate reactions

– Energy building• use sunlight• make energy (ATP)

– Sugar building• use ATP• use CO2

• make sugars (C6H12O6)

Energybuilding reactions

Sugarbuilding reactions

sun

ATPADP

CO2sugar

Energy Building Reactions

O2

H2O

Energy BuildingReactions

sunlight

ATP

H2O ATP O2light

energy ++

makes ATP energy releases oxygen

as a waste product

Sugar Building Reactions

sugarsC6H12O6

CO2

SugarBuilding

Reactions

ATP

CO2 C6H12O6 ADPATP ++

ADP

builds sugars uses ATP cycles ADP

back to make more ATP

Putting it all together

sugarsC6H12O6

CO2

ATP

ADP

H2O

O2

sunlight

CO2 H2O C6H12O6 O2light

energy + ++

SugarBuilding

Reactions

Energy Building

Reactions

Plants make both: ATP sugars

So what does a plant need?

• Takes in– CO2– H2O– light

• Releases– O2

• Produced and moved around– sugars

roots

shoot

leaves

How can a leaf do this? Let’s briefly examine the leaf structure

H2O CO2

CO2

O2 H2O

phloem (sugar)

xylem (water)

Stoma (pore/hole)

O2

Stomata • Function of stomata

– CO2 in

– O2 out

– H2O out

guard cell

Stomata (pore or hole)

Xylemcarry water up from roots

Phloem: food-conducting cells

carry sugars around the plant wherever they are needed new leavesfruitseeds

Putting it all together • Making a living…

– sunlight• leaves = solar collectors• photosynthesis

– gases: CO2 in & O2 out • stomata = gases in & out

– H2O• roots take in water from soil• pulled up by leaf evaporation

– nutrients• roots take in from soil

How are cellular respiration and photosynthesis connected?

glucose + oxygen carbon + water + energydioxide

C6H12O6 6O2 6CO2 6H2O ATP+ + +

Respiration

+ water + energy glucose + oxygencarbondioxide

6CO2 6H2O C6H12O6 6O2light

energy + ++

Photosynthesis

H2O

Energy cycle

Photosynthesis

Cellular Respiration

sun

The Great Circleof Life!

glucose O2CO2

plants

animals, plants

ATP

Resources

• www.bio.kimunity.com• Miller, Ken and Joe Levine. Prentice hall

Biology. Pearson Education Inc. New Jersey, 2005.