Chapter 8 Photosynthesis

8.1 Energy and Life10/27/2005

What is Energy?

Ability to do work

Autotrophs vs. Heterotrophs

Makes their ownfood

Use the energyof the sun

Ex. Plants

Obtains energyfrom the foodsthey consume

ATPAdenosine TriPhosphateMade up of:Adenine5 Carbon sugar (ribose)Three phosphate groupsKEY TO STORE &

RELEASE ENERGY

Storing Energy

ADP (Adenosine DiPhosphate)Similar to ATP2 phosphate groupsKey to the way in which living

things store energyAdd on available energy with a

phosphate to ADP to create ATPAnalogy --> Battery

Releasing EnergyHow is the energy stored in ATP

released?Breaking the chemical bond

between the second and thirdphosphate group

Basic energy source of all cells

What is energy used for?

Carry out active transport protein synthesisResponses to chemical

signals

ATP can only pack small

amounts of energy

P P

Adenine

Ribose

Phosphate

ADP

P P

Adenine

Ribose

Phosphate

ATP

P

8.2 Photosynthesis: An Overview

Photosynthesis

key cellular processidentified with energyproduction

Who goes throughphotosynthesis?PLANTS

Key PlayersvanHelmontMost of the gain in mass

comes from waterPriestley plant releases oxygen

IngenhouszPlant releases oxygen only

with the presence of light

Photosynthesis Equation

6CO2 6H2O+Carbon dioxide Water

REACTANTS

LIGHT

Photosynthesis Equation

C6H12O6 6O2+Sugar Oxygen

PRODUCTS

LIGHT

Photosynthesis Equation

6CO2 6H2O+ C6H12O6 6O2+LIGHT

DESCRIBE WHAT IS HAPPENING IN THE REACTION.

In photosynthesis, plants use the energyof sunlight to change water and carbondioxide into high-energy sugars andoxygen.

Lights and Pigments

Plants needLight

Form of energyPigment

light absorbing moleculeChlorophyl

Principal pigment in plants

8.3 The Reactions of Photosynthesis

Chloroplast where

photosynthesistakes place

thylakoidmembranes =saclikephotosyntheticmaterials found inchloroplast

Chloroplast Granum = stack

of thylakoid photosystems =

organization ofchlorophyll andother pigments light collectingunits of thechloroplast

Photosystems

2 part processLight dependent

In the thylakoid membranesLight independent (Calvin cycle)

In the stromaRegion outside the

thylakoid membranes

Electron Carriers Sunlight excites electrons in

chlorophyll electrons gain tons of energy high energy electrons need special

carriers from chlorophyll to othermolecules

Electron Transport Chain

carrier molecule = compound thatcan accept a PAIR of high-energyelectrons and transfer them toalong with MOST of their energy

NADP+One of the carrier moleculesNicotinamide adenine dinucleotide

phosphateAccepts and holds 2 high-energy

electrons along with H+ (hydrogenions)

This creates NADPHNADP+ + H+ --> NADPH = converts

energy sunglight into chemical form

NADPH carries high-energy electrons

produced by light absorptionin chlorophyll to chemicalreactions

used for synthesis ofmolecules

NADP+

2 high energy e-

H+

NADPH

8.3B

11 / 13 / 06

Light DependentReactions

requires lights uses energy fromlight to produceATP and NADPH

Light DependentReactions

Products OXYGEN GAS (02) 2 energy carriers ADP -- > ATP NADP+ --> NADPH

Light Dependent Reaction

o Light breaks up H2O tohave electrons, H+, and O

o O2 is released into the airo H+ released into thylakoid

membrane

1. Photosystem II

Light Dependent Reaction

e- absorb light

Creates high-energy electrons

2e- passed through e-transport chain

1. Photosystem II

Light Dependent Reaction

2 high energy electronsprovide Energy to moveH+ from stroma INTOthylakoid membrane

2. Electron Transport Chain

Light Dependent Reaction

o Light re-energizes electronso NADP+ picks up high energy

electrons and H+o H+ + NADP+ --> NADPH

(electron carriers)

3. Photosystem I

Light Dependent Reaction

o More H+ are pumped acrossthe membrane

o Inside = positive ionso Outside = more negativeo Importance = provides

energy to make ATP

4. Hydrogen Ion Movement

Light Dependent Reaction

a)ATP Synthase = proteinon cell membrane• Allows H+ to pass

through membraneb)ATP Synthase binds ADP

+ P+, creating ATP

5. ATP Formation

Light DependentReactions

Products OXYGEN GAS (02) 2 energy carriers ADP -- > ATP NADP+ --> NADPH

8.3 C11 / 14 / 06

Quickwrite

1. What

Calvin Cycle uses ATP and NADPH

from Light DependentReaction

Product - High energyCarbohydrates (sugar,starch)

Calvin Cycle

1. 6 CO2 enter the cycle fromatmosphere

2. Combine with six 5-CarbonMolecules

3. Result = twelve 3-CarbonMolecules

A. CO2 Enters the Cycle

Calvin Cycle

1. ATP and electrons fromNADPH used

2. 12 3-carbon moleculesconverted to higher energyforms

B. Energy Input

Calvin Cycle

1. Two 3-Carbon moleculesare removed• produce sugars, lipids,

amino acids, and othercompounds formetabolism

C. 6-Carbon Sugar Produced

Calvin Cycle

1. ATP is used2. Ten 3-Carbon molecules

convert back to six 5-Carbonmolecules

3. 5-Carbon molecules combinewith 6 CO2 molecules to beginthe next cycle

D. 5-Carbon Molecules Regenerated

Calvin Cycle

It takes 6CO2 to produce aSINGLE 6-Carbon sugarmolecule

Removes CO2 from air Sugar needed for growth and

development

Create a Flow Chart6 ____ go into cycle

Combines with six ________molecules

Results = _____________molecules

ATP and Electrons used fromNADPH

____________ moleculesconverted into higher

energy forms

Two __________Molecules removed

Produces________________________________________________

_______

______ 3-Carbon moleculesconverted back to 6

__________ molecule

Cycle repeats!

Factors Affecting Photosynthesis

shortage of water = slowor stop photosynthesis

temperature = damage orslow down how enzymeswork

Factors Affecting Photosynthesis

intensity of light = morelight, increasephotosynthesisUntil maximum levels

are hit