Photosynthesis & Photosynthesis & Cellular RespirationCellular Respiration

Chapter 5 Section 1Chapter 5 Section 1

ObjectivesObjectives

AnalyzeAnalyze the flow of energy through living the flow of energy through living systems.systems.

CompareCompare the metabolism of autotrophs with the metabolism of autotrophs with that of heterotrophs.that of heterotrophs.

DescribeDescribe the role of ATP in metabolim. the role of ATP in metabolim. DescribeDescribe how energy is released from ATP. how energy is released from ATP.

Key TermsKey Terms

PhotosynthesisPhotosynthesis AutotrophAutotroph HeterotrophHeterotroph Cellular RespirationCellular Respiration

Capturing the Energy of LifeCapturing the Energy of Life

All organisms require energyAll organisms require energy Some organisms obtain energy directly from Some organisms obtain energy directly from

the sun the sun This energy is used to make organic This energy is used to make organic

compounds that will serve as food for the compounds that will serve as food for the organismsorganisms

AutotrophsAutotrophs

Organisms that use energy from the sunlight or Organisms that use energy from the sunlight or form chemical bonds in inorganic substances form chemical bonds in inorganic substances to make organic compounds.to make organic compounds.

Only 10% of the Earth’s 40 million species are Only 10% of the Earth’s 40 million species are autotrophs.autotrophs.

Includes plants and some other types of Includes plants and some other types of organisms.organisms.

Also known as producers.Also known as producers.

HeterotrophsHeterotrophs

Organisms that must get energy from food Organisms that must get energy from food instead of directly from sunlight or inorganic instead of directly from sunlight or inorganic substances.substances.

Includes animals, humans & even mushrooms.Includes animals, humans & even mushrooms. Also known as consumersAlso known as consumers

Flow of EnergyFlow of Energy

PhotosynthesisPhotosynthesis

Process in which plants use the energy of Process in which plants use the energy of sunlight to convert water & carbon dioxide sunlight to convert water & carbon dioxide into high-energy carbohydrates (sugars & into high-energy carbohydrates (sugars & starches) and oxygen (waste product)starches) and oxygen (waste product)

Cellular RespirationCellular Respiration

Process by which cells produce Process by which cells produce energy from carbohydrates to do energy from carbohydrates to do chemical work in the cell.chemical work in the cell.

ATPATP Principal chemical compounds that cells use Principal chemical compounds that cells use

to store and release energy. The only to store and release energy. The only source of energy to do chemical work in the source of energy to do chemical work in the cell.cell.

Storing EnergyStoring Energy

ADP (adenosine diphosphate) is a compound that looks ADP (adenosine diphosphate) is a compound that looks almost like ATP.almost like ATP.

When a cell has energy available, it can store small When a cell has energy available, it can store small amounts of it by adding a phosphate group to ADP amounts of it by adding a phosphate group to ADP molecules.molecules.

Releasing Energy for Releasing Energy for Chemical WorkChemical Work

Energy is released by breaking the bond Energy is released by breaking the bond between the 2between the 2ndnd and 3 and 3rdrd phosphate. phosphate.

ATP + Enzymes ADP + P+ EnergyMitochondria

PHOTOSYNTHESISPHOTOSYNTHESIS

ObjectivesObjectives

SummarizeSummarize how energy is captured from how energy is captured from sunlight in the first stage of photosynthesis.sunlight in the first stage of photosynthesis.

AnalyzeAnalyze the function of electron transport the function of electron transport chains in the second stage of photosynthesis.chains in the second stage of photosynthesis.

RelateRelate the Calvin cycle to carbon dioxide the Calvin cycle to carbon dioxide fixation in the third stage of photosynthesis.fixation in the third stage of photosynthesis.

IdentifyIdentify three environmental factors that affect three environmental factors that affect the rate of photosynthesis.the rate of photosynthesis.

Key TermsKey Terms

PigmentPigment ChlorophyllChlorophyll CarotenoidCarotenoid ThylakoidThylakoid Electron Transport Electron Transport

ChainChain

NADPHNADPH Carbon Dioxide Carbon Dioxide

FixationFixation Calvin CycleCalvin Cycle

PhotosynthesisPhotosynthesis

Carbon dioxide (COCarbon dioxide (CO22)) requiring requiring process that uses process that uses light energy light energy (photons)(photons) and and water (Hwater (H22O)O) to to produce produce organic macromolecules organic macromolecules (glucose).(glucose).

6CO6CO22 + 6H + 6H22O O C C66HH1212OO66 + 6O + 6O22glucoseglucose

SUNphotonsphotons

Where does Where does Photosynthesis occur?Photosynthesis occur?

Plants/Autotrophs Plants/Autotrophs – produce their – produce their own food own food (glucose)(glucose)

Process called Process called photosynthesisphotosynthesis Mainly occurs in the Mainly occurs in the leaves:leaves:

a.a.stoma - poresstoma - pores

b.b.mesophyll cellsmesophyll cells

StomaMesophyllCell

Chloroplast

The Stages of PhotosynthesisThe Stages of Photosynthesis

Stage 1Stage 1 Energy is captured from sunlight by chlorophyll and other Energy is captured from sunlight by chlorophyll and other

pigments present.pigments present. Stage 2Stage 2

Light energy is converted to chemical energy, which is Light energy is converted to chemical energy, which is temporarily stored in ATP & the energy carrier molecule temporarily stored in ATP & the energy carrier molecule NADPHNADPH

Stage 3Stage 3 The chemical energy stored in ATP & NADPH powers the The chemical energy stored in ATP & NADPH powers the

formation of organic compounds, using the COformation of organic compounds, using the CO2 2 to make to make Glucose.Glucose.

Stages of PhotosynthesisStages of Photosynthesis

The Photosynthesis EquationThe Photosynthesis Equation

6CO2 + 6H20 C6H12O6 + 6O2Light

Carbon Dioxide

Water Sugars Oxygen

(High Energy)

Stage 1: Absorption of Stage 1: Absorption of Light EnergyLight Energy

How does a human eye or leaf absorb How does a human eye or leaf absorb light?light?

Visible SpectrumVisible Spectrum

Sunlight contains a Sunlight contains a mixture of all the mixture of all the wavelengths (colors) of wavelengths (colors) of visible light.visible light.

When sunlight passes When sunlight passes through a prism, the through a prism, the prism separates the light prism separates the light into different colors.into different colors.

Visible SpectrumVisible Spectrum

When light strikes an object, it is, absorbed, When light strikes an object, it is, absorbed, transmitted or reflected.transmitted or reflected.

When all colors are absorbed the object When all colors are absorbed the object appears black.appears black.

When all colors are reflected the object When all colors are reflected the object appears white.appears white.

If only one color is reflected the object appears If only one color is reflected the object appears that color.that color.

PigmentsPigments

Light-absorbing substancesLight-absorbing substances Absorb only certain wavelengths and reflect Absorb only certain wavelengths and reflect

all others.all others.

ChlorophyllChlorophyll

The primary pigment in plants.The primary pigment in plants. Absorbs mostly blue & red lightAbsorbs mostly blue & red light Reflects green & yellow lightReflects green & yellow light 2 Types of chlorophyll2 Types of chlorophyll

Chlorophyll Chlorophyll a - a - blue greenblue green Chlorophyll bChlorophyll b -yellow green -yellow green

CarotenoidsCarotenoids

Accessory pigments:Accessory pigments:

-Carotenoids - -Carotenoids - orangeorange

-Xanthrpphyll – -Xanthrpphyll – yellowyellow

-Anthocyanin-Anthocyanin – – redred

-Lutein –-Lutein – grey/browngrey/brown Absorb wavelengths of light different from Absorb wavelengths of light different from

those absorbed by chlorophyll a & b.those absorbed by chlorophyll a & b.

Light Absorption During Light Absorption During PhotosynthesisPhotosynthesis

ThylakoidsThylakoids

Saclike photosynthetic membranes located Saclike photosynthetic membranes located inside the chloroplasts.inside the chloroplasts.

Arranged in stacks known as grana (singular: Arranged in stacks known as grana (singular: granum).granum).

ThylakoidsThylakoids

When light strikes a thylakoid in a chloroplast, When light strikes a thylakoid in a chloroplast, energy is transferred to electrons in energy is transferred to electrons in chlorophyll, exciting the chlorophyll.chlorophyll, exciting the chlorophyll.

This energy transfer causes electrons to jump This energy transfer causes electrons to jump to a higher energy level.to a higher energy level.

Electrons with extra energy are said to be Electrons with extra energy are said to be “excited”“excited”

Excited ElectronsExcited Electrons

Excited electrons jump from chlorophyll Excited electrons jump from chlorophyll molecules to other nearby molecules in the molecules to other nearby molecules in the thylakoid membrane.thylakoid membrane.

These electrons must be replaced by other These electrons must be replaced by other electrons.electrons.

Plants get these replacement electrons from Plants get these replacement electrons from water molecules.water molecules.

Replacement ElectronsReplacement Electrons

Water molecules are splitWater molecules are split by an enzyme by an enzyme inside the thylakoid.inside the thylakoid.

Chlorophyll molecules take the electrons from Chlorophyll molecules take the electrons from the hydrogen atoms.the hydrogen atoms.

Oxygen from the disassembled water Oxygen from the disassembled water molecules combine to form oxygen gas and molecules combine to form oxygen gas and this is given off at the end of stage 1 as a waste this is given off at the end of stage 1 as a waste product of photosynthesis.product of photosynthesis.

Stage 2: Conversion of Stage 2: Conversion of Light EnergyLight Energy

Light DependentLight Dependent

Conversion of Light EnergyConversion of Light Energy

Excited electrons that leave chlorophyll Excited electrons that leave chlorophyll molecules are used to produce new molecules, molecules are used to produce new molecules, including ATP, that temporarily store chemical including ATP, that temporarily store chemical energy.energy.

Electron Transport ChainsElectron Transport Chains

Excited electrons are passed through a series Excited electrons are passed through a series of molecules along the thylakoid membrane.of molecules along the thylakoid membrane.

This is called the electron transport chain.This is called the electron transport chain. This provides the energy needed to make ATP.This provides the energy needed to make ATP.

NADPHNADPH

A second electron transport chain provides A second electron transport chain provides energy used to make NADPHenergy used to make NADPH

NADPH is an electron carrier that provides the NADPH is an electron carrier that provides the high-energy electrons needed to make carbon-high-energy electrons needed to make carbon-hydrogen bonds in the 3hydrogen bonds in the 3rdrd stage of stage of photosynthesisphotosynthesis

Light-Dependent Reactions Light-Dependent Reactions SummarizedSummarized

1.1. Pigment molecules in the thylakoids of Pigment molecules in the thylakoids of chloroplasts absorb light energy.chloroplasts absorb light energy.

2.2. Electrons in the pigments are excited by light Electrons in the pigments are excited by light & move through electron transport chains in & move through electron transport chains in thylakoid membranes.thylakoid membranes.

3.3. These electrons are replaced by electrons These electrons are replaced by electrons from water molecules that are split.from water molecules that are split.

Light-Dependent Reactions Light-Dependent Reactions Summarized (cont)Summarized (cont)

4.4. Oxygen atoms from water molecules Oxygen atoms from water molecules combine to form oxygen gas.combine to form oxygen gas.

5.5. Hydrogen ions accumulate inside thylakoids, Hydrogen ions accumulate inside thylakoids, setting up a concentration gradient that setting up a concentration gradient that provides the energy to make ATP and provides the energy to make ATP and molecules of NADPH to be used in the Dark molecules of NADPH to be used in the Dark Reaction, the third stage.Reaction, the third stage.

Stage 3: Storage of Stage 3: Storage of EnergyEnergy

““Dark Reaction”Dark Reaction”

Dark Reaction (third stage)Dark Reaction (third stage) of Photosynthesis of Photosynthesis

Carbon atoms from carbon dioxide in the atmosphere Carbon atoms from carbon dioxide in the atmosphere and the H molecules from the NADPH of the light and the H molecules from the NADPH of the light reactions are used to make organic compounds in reactions are used to make organic compounds in which chemical energy is stored in glucose which chemical energy is stored in glucose molecules.molecules.

The transfer of carbon dioxide to organic compounds The transfer of carbon dioxide to organic compounds (glucose) is called carbon dioxide fixation or the (glucose) is called carbon dioxide fixation or the Calvin Cycle.Calvin Cycle.

Calvin CycleCalvin Cycle

Most common method of carbon dioxide Most common method of carbon dioxide fixation.fixation.

Series of enzyme-assisted chemical reactions Series of enzyme-assisted chemical reactions that produce a three-carbon sugar.that produce a three-carbon sugar.

Dark Reaction SummarizedDark Reaction Summarized

1.1. Each molecule of carbon dioxide is added to Each molecule of carbon dioxide is added to a five-carbon compound by an enzyme using a five-carbon compound by an enzyme using the energy from the ATP and the splitting of the energy from the ATP and the splitting of the NADPH from the Light Reaction.the NADPH from the Light Reaction.

2.2. The resulting six-carbon compound splits The resulting six-carbon compound splits into two three-carbon compounds. into two three-carbon compounds. Phosphate groups from ATP & electrons Phosphate groups from ATP & electrons from NADPH are added to the three-carbon from NADPH are added to the three-carbon compounds, forming three-carbon sugars.compounds, forming three-carbon sugars.

Calvin Cycle Summarized (cont)Calvin Cycle Summarized (cont)

3.3. The resulting three-carbon sugars The resulting three-carbon sugars are used to make organic are used to make organic compounds— glucose —in which compounds— glucose —in which energy is stored for later use by the energy is stored for later use by the organism.organism.

Factors that Affect PhotosynthesisFactors that Affect Photosynthesis

LightLight Rate increases as light intensity increases until all Rate increases as light intensity increases until all

the pigments are being used.the pigments are being used. Concentration of carbon dioxideConcentration of carbon dioxide

Once a certain concentration of carbon dioxide is Once a certain concentration of carbon dioxide is present, photosynthesis cannot proceed fasterpresent, photosynthesis cannot proceed faster

TemperatureTemperature Most efficient within a certain range of Most efficient within a certain range of

temperatures.temperatures.

Question:Question:

During the fall, During the fall, what causes what causes the leaves to the leaves to

change colors?change colors?

Fall ColorsFall Colors In addition to the chlorophyll In addition to the chlorophyll

pigments, there are pigments, there are other other pigmentspigments present present

During the fall, the During the fall, the green green chlorophyll pigments are chlorophyll pigments are greatly reducedgreatly reduced revealing the revealing the other pigmentsother pigments

CarotenoidsCarotenoids are pigments that are pigments that are either are either redred, , orangeorange, or , or yellowyellow

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