CHAPTER 8: PHOTOSYNTHESIS

8-1 Energy of Life

Energy=

Living organisms depend on energy.

Living things get energy from _______.

The ultimate source of energy is the _____.

The ability to do work

food

sun

A. Autotrophs and Heterotrophs

Autotrophs=

o Example: plants use sunlight to make food

Heterotrophs=

o Example: ___________- eat plants ___________- eat animals that have stored energy from plants they eat

___________- eat decomposing organisms

Organisms that make their own food

Organisms that need to consume food for energy

herbivores

carnivores

detritovores

Adenine Ribose 3 Phosphate groups

Section 8-1

ATPB. Chemical Energy and ATP•Forms of energy: light, heat, electricity, and

•_____ (Adenosine Triphosphate)=

Chemical energy (stored in bonds)

ATP

The basic energy source (chemical energy) of all cells

1. Storing Energy• ADP (Adenosine Diphospate) contains ____ phosphates

instead of 3.

• If a cell has extra energy,

2. Releasing Energy

• To release energy stored in ATP,

2

Small amounts can be stored by adding a phosphate group to ADP molecules to produce ATP.

The cell can break the high energy bond betweenthe 2nd and 3rd phosphate group

ADP ATP

Energy

EnergyAdenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP)

Partiallychargedbattery

Fullychargedbattery

Section 8-1

Figure 8-3 Comparison of ADP and ATP to a Battery

C. Using Biochemical Energy

How ATP is used in the cell- - aids in - -

Cells contain a small amount of ATP. Only enough to provide a few seconds of activity.

ATP is great at ________________ but not good at

Glucose stores ___ times more energy than ATP.

The energy stored in Glucose can be used to

Carry out active transportmoving organelles throughout the cell

Protein synthesisProducing light (ex. fireflys)

transferring energy Storing large amounts of energy

90

regenerate ATP when the cell needs it.

8-2 Photosynthesis: An Overview

Photosynthesis=

Plants convert ______________ into ______________ through a series of oxidation/reduction reactions.

Process where plants use energy of sunlight to convert water and carbon dioxide into high-energy Carbohydrates-sugars-starches-and oxygen, a waste product.

Sunlight energy Chemical energy

6 CO2 + 6H2O + SUNLIGHT → C6H12O6 (SUGAR) + 6O2

6 CO2 + 6H2O + SUNLIGHT → C6H12O6 (SUGAR) + 6O2

sunlight

O2

CO2

H2O

C6H12O6

Reduction: Gain electrons

Oxidation: Lose electrons

REDOX REACTIONSLEO: Lose Electrons Oxidationgoes GER: Gain Electrons Reduction

Light Energy

Chloroplast(Chlorophyll)

CO2 + H2OSugars + O2

Section 8-2

Photosynthesis: Reactants and Products

A. Investigating Photosynthesis Investigations into photosynthesis began with

the following question:

“When a tiny seedling grows into a tall tree with a mass of several tons, where does the tree’s increase in mass come

from?”

1. ______________ Experiment (1643)

Put soil in pot and took mass

Took a seedling and took mass

Put seed in soil...watered...waited five years... the seedling became a tree.

He concluded that He determined the

                                      

    

Van Helmont’s

the mass came from water

“hydrate” in the carbohydrate portion of photosynthesis

Von Helmont Willow Tree Experiment

http://www.teachersdomain.org/resource/tdc02.sci.life.stru.photosynth/

2.3 kg. (5 lb.) plant90.8 kg (200 lbs). soil

76.8 kg (169 lbs. 3 oz.)  Soil 57 g less

5 years

2. ___________ Experiment (1771)

Put a lit candle in a bell jar- Placed a mint plant in the jar with the candle-

Concluded

He determined

                                        

                    

Priestly’s

The flame died out.

Flame lasted longer

plants release a substance neededfor candle burning.

plants release oxygen

Alternate Priestly Experiment

• Credit: The National Science Teachers Association

3. ________________Experiment (1779)

Put aquatic plants in light...

Put aquatic plants in dark... He determined:

4. _______________ (1948)

He determines

Known as the

Jan Ingenhousz

produced oxygen

No oxygen

Light is needed to produce oxygen

Melvin Calvin

carbon’s path to make glucose

Calvin’s cycle

B. Light and Pigments Photosynthesis requires ______ (soil), ____________ (air),

and ____ (sun), and ________ (a molecule in chloroplasts).

Energy from the sun is in the form of _____.

Sunlight= perceived as white light=

The wavelengths you can see are part of the _______________.

Plants capture light with light absorbing molecules called ________.

The main pigment is chlorophyll (2 kinds)1. 2.

water Carbon dioxidelight chlorophyll

light

A mixture of different wavelengths

Visible Spectrum

pigments

Chlorophyll aChlorophyll b

Absorption of Light byChlorophyll a and Chlorophyll b

V B G YO R

Chlorophyll b

Chlorophyll a

Section 8-2

Figure 8-5 Chlorophyll Light Absorption

Chlorophyll absorbs light in the __________ and ___ wavelengths

Gammarays

X-rays UV Infrared Micro-waves

Radiowaves

Visible light

Wavelength (nm)

Blue-violetred

REDORANGEYELLOWGREENBLUEINDIGO VIOLET

Chlorophyll reflects ______ wavelengths (that’s why plants appear green)

The energy absorbed by chlorophyll is transferred to _________ (in chloroplasts) which makes photosynthesis work.

green

electrons

QUESTION: So why do plants leaves change color in the fall?

Colorful leaves signal the changes of autumn. As nights grow longer and cooler, the leaves no longer produce chlorophyll, the pigment that makes leaves green and enables the process of photosynthesis. As the green pigment wanes, other pigments take over, producing the brilliant reds, oranges, and yellows of fall foliage.

• The location and structure of chloroplasts

Figure 7.2

LEAF CROSS SECTION MESOPHYLL CELLLEAF

Chloroplast

Mesophyll

CHLOROPLAST Intermembrane space

Outermembrane

Innermembrane

ThylakoidcompartmentThylakoidStroma

Granum

StromaGrana

8.3 INFORMATIONOverview of Photosynthesis Light and Dark Reactions

Light

Chloroplast

Reflectedlight

Absorbedlight

Transmittedlight

8-3 The Reactions of Photosynthesis A. Inside a Chloroplast

• Site of Photosynthesis=

The chloroplasts

Photosynthesis is a two part process:1.

-aka: 2.

-aka: -aka: -aka:

ChloroplastLight

O2Sugars

CO2

Light-Dependent Reactions

CalvinCycle

NADPHATP

ADP + PNADP+Chloroplast

Section 8-3

Figure 8-7 Photosynthesis: An Overview

Light-dependent reactions (located in thylakoid membranes)Light Reaction

Light-independent reactions (located in stroma)Dark reactionCalvin CycleCarbon fixation

H20

• An overview of photosynthesis

Figure 7.5

Light

Chloroplast

LIGHTREACTIONS

(in grana)

CALVINCYCLE

(in stroma)

Electrons

H2O

O2

CO2

NADP+

ADP+ P

Sugar

ATP

NADPH

B. Electron Carriers Sunlight energy is transferred to

The electrons

High energy electrons require ANALOGY: If you wanted to transfer hot coals from one campfire to another, it requires a special carrier like a pan or bucket.

Electron carriers pass electrons from carrier to carrier to carrier;

A Key electron carrier in photosynthesis is NADP+. NADP+ + + →→ (electron carrier) (high energy electrons) (hydrogen ions) (energy storing compound)

When energy is needed to do cellular work, the

electrons in chlorophyll.

gain a lot of energy.

a special carrier (molecule/compound).

Forming an electron transport chain.

2e- H+ NADPH

Covalent bonds of NADPH are broken to releasethe high energy electrons.

C. Light-Dependent Reactions (Requires Light)·   Located in the ___________________________

·   In the light reaction, ___________ is used to

produce _____ and _______

http://www.fw.vt.edu/dendro/forestbiology/photosynthesis.swf

thylakoid membrane

light energyATP NADPH

PSII PSI

2H2O

O2 + 4H+

Electron Transport Chain

NADP+ NADPH

Electron Transport Chain

light

light

ADP ATPe~

4e~

e~

e~e~

e~

e~

Overview of the Light Reaction

http://www2.kumc.edu/netlearning/examples/flash/photosyn2.html

Primaryelectron acceptor

Primaryelectron acceptor

Electron transport chain

Electron transport

Photons

PHOTOSYSTEM I

PHOTOSYSTEM II

Energy forsynthesis of

by chemiosmosis

http://www2.kumc.edu/netlearning/examples/flash/photosyn2.html

KEY PLAYERS IN LIGHT REACTION:

    Photosystem I and II:

    Electron carriers:

    Water:

• ATP Synthase:

Clusters of chlorophyll pigment

ADP and NADP+

Donates electrons

Enzyme (protein) that makes ATP

Figure 7.7C

Primaryelectron acceptor

Photon

Reaction center

PHOTOSYSTEM

Pigmentmoleculesof antenna

HydrogenIon Movement

Photosystem II

InnerThylakoidSpace

ThylakoidMembrane

Stroma

ATP synthase

Electron Transport Chain Photosystem I ATP Formation

Chloroplast

Light Reaction Process:

LIGHT REACTIONS8.3

• The production of ATP by chemiosmosis in photosynthesis

Figure 7.9

Thylakoidcompartment(high H+)

Thylakoidmembrane

Stroma(low H+)

Light

Antennamolecules

Light

ELECTRON TRANSPORT CHAIN

PHOTOSYSTEM II PHOTOSYSTEM I ATP SYNTHASE

A. Photosystem II (PSII) * Absorbs light to

 2H2O

 o  e- =

o  O2 =

o  H+=

B. Electron Transport Chain * The light energy

* The electrons get passed

split (break up) water molecules

→ 4H+ + 4e- + O2

Donated to chlorophyll

Released into air providing oxygen for us

Released inside the thylakoid membrane

excites electrons increasing their energy level.

down an electron transport chain tophotosystem I (PSI)

C. Photosystem I·        Light energy energizes electrons.·        NADP+ accepts the electrons and an H+ and are

used to make _________.  D. Hydrogen Ion Movement

·        When water splits,

·        The difference in charges

http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120068/bio05.swf::Proton%20Pump

E. ATP Formation·        _____ do not cross the membrane directly.

It needs the help of a membrane protein.·        H+ ions pass through the protein:

NADPH

H+ ions fill up the inner thylakoid membrane (making it positively charged). As a result, the stroma is negatively charged.

Provides the energy to make ATP.

Ions

ATP synthase is an enzyme that converts ADP to ATP

PRODUCTS OF THE LIGHT REACTION:

·   ____ : Released in the air

·  ______________: These contain abundant chemical energy but they are unstable. So, they are used to power the dark reaction to _________________ which can store the energy for longer periods of time.

O2

ATP & NADPH

help build glucose

DARK REACTIONS8.3

ChloropIast

CO2 Enters the Cycle

Energy Input

5-CarbonMoleculesRegenerated

Sugars and other compounds

6-Carbon SugarProduced

Section 8-3 D. The Calvin Cycle (dark reaction; light independent) * Occurs in the http://faculty.nl.edu/jste/calvin_cycle.htm

Figure 8-11 Calvin CycleStroma with or without light.

The Calvin Cycle(CO2)

(Unstable intermediate)

ATP

ADP +

ADP +

(Sugars and other carbohydrates)

NADPH

NADP+

(PGAL)

(PGAL)

ATP

(PGAL)

(RuPB)

DARK REACTION PROCESS: A. CO2 enters the system•              •  product=

B. Energy input• The _________________________________ are used to

C. 6-Carbon Sugar is produced• ___ of the 12 3-C are used to make glucose and other compounds.

D. 5-Carbon Molecules Regenerated• ___ remaining 3-C are converted into 6 5-C molecules

6 CO2 combines with 6 5-C compounds12 3-C compounds

ATP & NADPH (from the light reaction)convert the 12 3-C compounds into a higher energy form.

2

10

PRODUCTS OF THE CALVIN CYCLE (DARK REACTION):*                     

E. Factors Affecting Photosynthesis*          *   Plants often have a ______ coating to protect against

*        * The greater the _____________, the better photosynthesis functions (up to a point).

High Energy Sugars

Shortage of water can stop/slow down photosynthesis

waxy

Very low/high temperatures (damages enzymes) can stop/slow down photosynthesis (optimal temp.= 0°– 35° C

Light intensity

Photosynthesis

includes

of

take place intakes place in uses

to produce to produce

use

Light-dependentreactions

Calvin cycle

Thylakoidmembranes Stroma NADPHATPEnergy from

sunlight

ATP NADPH O2 Chloroplasts High-energysugars

Section 8-3

Concept Map