Introduction to slide shareIntroduction to slide share

All the work is a combination of the following people. They are:All the work is a combination of the following people. They are:

Dephillips , A (2007). Dephillips , A (2007). PhotosynthesisPhotosynthesisSmullin ,B (2010). Pre IB Biology Pho.tosynthesis.

Tamara , (2010). Biology Photosynthesis.

Chapter 7 1

Chapter 7Chapter 7

PhotosynthesisPhotosynthesis

Chapter 7 3

What Is Photosynthesis?What Is Photosynthesis?

Early cells evolved the ability to perform Early cells evolved the ability to perform photosynthesis about 2 billion years agophotosynthesis about 2 billion years ago

PhotosynthesisPhotosynthesis is the ability to capture is the ability to capture sunlight energy and convert it to chemical sunlight energy and convert it to chemical energyenergy

Most forms of life on Earth depend on the Most forms of life on Earth depend on the chemical energy produced by chemical energy produced by photosynthetic organismsphotosynthetic organisms

Chapter 7 4

The Photosynthetic EquationThe Photosynthetic Equation

Chapter 7 5

Gases, Sugar, and Water CycleGases, Sugar, and Water Cycle

Production of carbon compounds like Production of carbon compounds like glucose (photosynthesis) is linked with glucose (photosynthesis) is linked with energy extraction (in cellular respiration)energy extraction (in cellular respiration)

Water, COWater, CO22, sugar, and O, sugar, and O22 cycle between the cycle between the two processestwo processes

Photosynthesis and cellular respiration are Photosynthesis and cellular respiration are interconnectedinterconnected

Chapter 7 6Interconnections:Interconnections:Photosynthesis & RespirationPhotosynthesis & Respiration

Chapter 7 7

Adaptations for PhotosynthesisAdaptations for Photosynthesis

LeavesLeaves

ChloroplastsChloroplasts

Chapter 7 8Structures ofStructures ofPhotosynthesisPhotosynthesis

Chapter 7 9

leavesleaves

Chapter 7 10

Leaf AnatomyLeaf Anatomy

Adjustable pores called Adjustable pores called stomatastomata allow for allow for entry of air with COentry of air with CO22

Inner Inner mesophyllmesophyll cell layers contain cell layers contain majority of chloroplastsmajority of chloroplasts

Vascular bundlesVascular bundles (veins) supply water (veins) supply water and minerals to the leaf while carrying and minerals to the leaf while carrying sugars away from the leafsugars away from the leaf

Chapter 7 11

Internal Leaf StructureInternal Leaf Structure

Internal leaf structure is crucial to Internal leaf structure is crucial to photosynthesis since photosynthesis photosynthesis since photosynthesis occurs primarily in the leaves of land occurs primarily in the leaves of land plans plans

Chapter 7 12

Leaf StructureLeaf Structure

MesophyllMesophyllCellsCells

MesophyllMesophyllCellsCells

Upper EpidermisUpper EpidermisUpper EpidermisUpper Epidermis

LowerLowerEpidermisEpidermis

LowerLowerEpidermisEpidermisVeinVeinVeinVein StomaStomaStomaStoma

Chapter 7 13

Chapter 7 14

Anatomy of a ChloroplastAnatomy of a Chloroplast

The The stroma stroma is the semi-fluid medium is the semi-fluid medium within the inner membranewithin the inner membrane

Disk-shaped sacs called Disk-shaped sacs called thylakoidsthylakoids found within the stroma in stacks found within the stroma in stacks called called granagrana

ChloroplastsChloroplasts

similar to mitochondriasimilar to mitochondria

outer and inner membraneouter and inner membrane

membranous sacs: THYLAKOIDSmembranous sacs: THYLAKOIDS

thylakoids = concentrated in stacks thylakoids = concentrated in stacks called GRANAcalled GRANA

thylakoids: contain chlorophyll thylakoids: contain chlorophyll (capture light)(capture light)

filled with fluid: STROMA (where filled with fluid: STROMA (where sugars are made from COsugars are made from CO2 2 ))

Chapter 7 16Lets take a close look at the diagramatic Lets take a close look at the diagramatic representation of a chloroplastsrepresentation of a chloroplasts

Inner & OuterInner & OuterMembranesMembranes

ThylakoidsThylakoids

GranumGranum

Stroma Stroma (space)(space)

Chapter 7 17

The Energy in Visible LightThe Energy in Visible Light

The sun radiates The sun radiates electromagnetic energyelectromagnetic energyVisible light is radiation falling between 400-Visible light is radiation falling between 400-750 nanometers of wavelength750 nanometers of wavelength

Packets of energy called Packets of energy called photons photons with with different energy levelsdifferent energy levels• Short-wavelength photons are very Short-wavelength photons are very

energeticenergetic• Longer-wavelength photons have lower Longer-wavelength photons have lower

energiesenergies

Chapter 7 18Light, ChloroplastLight, ChloroplastPigments, & PhotosynthesisPigments, & Photosynthesis

Gamma RaysGamma Rays X-RaysX-Rays UVUV InfraredInfrared Micro-Micro-waveswaves

RadioRadioWavesWaves

Visible LightVisible Light

400400 450450 500500 550550 600600 650650 700700 750750Wavelength (nanometers, nm)Wavelength (nanometers, nm)

ee--

Simple Calvin Simple Calvin Cycle Cycle

animations: animations:

Chapter 7 28

Light Captured by PigmentsLight Captured by Pigments

Action of light-capturing pigmentsAction of light-capturing pigments• AbsorptionAbsorption of certain wavelengths of certain wavelengths

(light is “trapped”)(light is “trapped”)• ReflectionReflection of certain wavelengths of certain wavelengths

(light bounces back)(light bounces back)• TransmissionTransmission of certain wavelengths of certain wavelengths

(light passes through)(light passes through)

Chapter 7 29

Light Captured by PigmentsLight Captured by Pigments

Absorbed light drives biological Absorbed light drives biological processes when it is converted to processes when it is converted to chemical energychemical energy

Common pigments found in Common pigments found in chloroplasts include:chloroplasts include:• ChlorophyllChlorophyll aa andand bb• Accessory pigments such as Accessory pigments such as

carotenoidscarotenoids

Chapter 7 30

Light Captured by PigmentsLight Captured by Pigments

Chlorophyll a and bChlorophyll a and b absorb violet, blue, absorb violet, blue, and red light but reflect green light and red light but reflect green light (hence they appear green)(hence they appear green)

CarotenoidsCarotenoids absorb blue and green light absorb blue and green light but reflect yellow, orange, or red (hence but reflect yellow, orange, or red (hence they appear yellow-orange)they appear yellow-orange)

Pigment absorbs visible lightPigment absorbs visible light

Chapter 7 31

GlucoseGlucose

OO22

Overview of PhotosynthesisOverview of Photosynthesis

Light-DependentLight-DependentReactionsReactions

(in thylakoids)(in thylakoids)

Light-IndependentLight-IndependentReactionsReactions

(in stroma)(in stroma)

DepletedDepletedCarriersCarriers

(ADP, NADP(ADP, NADP++))

DepletedDepletedCarriersCarriers

(ADP, NADP(ADP, NADP++))

EnergizedEnergizedCarriersCarriers

(ATP, NADPH)(ATP, NADPH)

HH22OO

COCO22

Chapter 7 32The PhotosystemsThe Photosystems

Chapter 7 34Thylakoid Structure & Thylakoid Structure & Light-Dependent ReactionsLight-Dependent Reactions

Chapter 7 35

Oxygen as a By-productOxygen as a By-product

Chapter 7 36Chemiosmosis 1Chemiosmosis 1

Chapter 7 37

Chemiosmosis 2Chemiosmosis 2

Chapter 7 38

CC33 Cycle Has Three Parts Cycle Has Three Parts

1. Carbon fixation (carbon capture)1. Carbon fixation (carbon capture)• 6 Ribulose bisphosphate (RuBP) 6 Ribulose bisphosphate (RuBP)

molecules combine with 6COmolecules combine with 6CO22

• Fixation step and subsequent Fixation step and subsequent reactions yield twelve 3-carbon reactions yield twelve 3-carbon phosphoglyceric acid (PGA) phosphoglyceric acid (PGA) molecules…molecules…

Chapter 7 39

CC33 Cycle Has Three Parts Cycle Has Three Parts

2. Synthesis of Glyceraldehyde 3-2. Synthesis of Glyceraldehyde 3-Phosphate (G3P)Phosphate (G3P)

• Energy is donated by ATP and NADPHEnergy is donated by ATP and NADPH• Phosphoglyceric acid (PGA) molecules Phosphoglyceric acid (PGA) molecules

are converted into glyceraldehyde 3-are converted into glyceraldehyde 3-Phophate (G3P) molecules …Phophate (G3P) molecules …

Chapter 7 40

CC33 Cycle Has Three Parts Cycle Has Three Parts

3. Regeneration of Ribulose bis-3. Regeneration of Ribulose bis-phosphate (RuBP)phosphate (RuBP)

• 10 of 12 G3P molecules converted into 10 of 12 G3P molecules converted into 6 RuBP molecules6 RuBP molecules

• 2 of 12 G3P molecules used to 2 of 12 G3P molecules used to synthesize 1 glucosesynthesize 1 glucose

• ATP energy used for these reactionsATP energy used for these reactions

Chapter 7 41The CThe C33 Cycle of Cycle of Carbon Carbon FixationFixation…or……or…Dark ReactionsDark Reactions…or……or…Light-Light-Independent Independent ReactionsReactions…or……or…Calvin CycleCalvin Cycle…or……or…Calvin-Benson Calvin-Benson CycleCycle

Chapter 7 42

Relationship Between ReactionsRelationship Between Reactions

The “photo” part of photosynthesis The “photo” part of photosynthesis refers to the capture of light energy refers to the capture of light energy (light dependent reactions)(light dependent reactions)

The “synthesis” part of photosynthesis The “synthesis” part of photosynthesis refers to glucose synthesis (light-refers to glucose synthesis (light-inindependent reactions)dependent reactions)

Chapter 7 43

Relationship Between ReactionsRelationship Between Reactions

Light dependent reactions produce ATP Light dependent reactions produce ATP and NADPH which is used to drive and NADPH which is used to drive light-independent reactionslight-independent reactions

Depleted carriers (ADP and NADPDepleted carriers (ADP and NADP++) ) return to light-dependent reactions for return to light-dependent reactions for rechargingrecharging

Chapter 7 44

A Summary of PhotosynthesisA Summary of Photosynthesis

Light-dependent Light-dependent reactions occur reactions occur

in thylakoidsin thylakoids Light-Light-independent independent reactions (creactions (c33

cycle) occur in cycle) occur in stromastroma

plateauplateau

At low COAt low CO22 concentration, concentration, rate is positively correlated rate is positively correlated

with concentrationwith concentration

COCO22 is a substrate in an is a substrate in an enyme-catalysed light-enyme-catalysed light-dependent reactiondependent reaction. .

At low light intensity, rate of At low light intensity, rate of photosynthesis is proportional to photosynthesis is proportional to

light intensity. light intensity.

plateauplateau

Increased temp. Increased temp. gives increased gives increased

energy and energy and increased rate increased rate

of of photosynthesisphotosynthesis

Optimum Optimum temperaturetemperature

Above the Above the optimum optimum

temp., enzymes temp., enzymes are denatured are denatured and rate drops and rate drops

steeply. steeply.

Which enzymes Which enzymes are used in are used in

respiration? respiration?

For more help and useful For more help and useful animations, visit: animations, visit:

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Chapter 7Chapter 7

The endThe end

ReferencesReferences

Dephillips, A. (2007).Photosynthesis,Dephillips, A. (2007).Photosynthesis, http://www.slideshare.net/MrDPMWest/ap-bio-ch7-power-point http://www.slideshare.net/MrDPMWest/ap-bio-ch7-power-point

Smullen,B.(2010). Pre IB Biology Photosynthesis,Smullen,B.(2010). Pre IB Biology Photosynthesis, http://www.slideshare.net/smullen57/1-power-pt-photosynthesis http://www.slideshare.net/smullen57/1-power-pt-photosynthesis

Tamara, (2010) . Biology 8.3, http://www.slideshare.net/tamarad423/biology-83

Chapter 7 50