Energy in a CellEnergy in a Cell

The Need for EnergyThe Need for Energy

Cell EnergyCell Energy

Autotrophs – make their Autotrophs – make their own foodown food

Heterotrophs must get Heterotrophs must get energy from consuming energy from consuming other organismsother organisms

Autotrophs – such as Autotrophs – such as plants, make food from plants, make food from light energylight energy

Light energy is Light energy is transformed into chemical transformed into chemical energy as chemical energy as chemical bondsbonds

All chemical bonds All chemical bonds store energy, some store energy, some more than othersmore than others

There is a LOT of energy in a There is a LOT of energy in a carbon to carbon bond (these carbon to carbon bond (these are in organic molecules such are in organic molecules such as sugar)as sugar)

There is too much energy in a There is too much energy in a carbon-carbon bond for carbon-carbon bond for normal cell processesnormal cell processes

So…mitochondria break So…mitochondria break down organic compounds, down organic compounds, like sugars and fats, and like sugars and fats, and convert the energy into convert the energy into ATPATP or adenosine or adenosine triphosphatetriphosphate

ATPATPComposed of:Composed of:

Adenine – amino acidAdenine – amino acidRibose – 5-carbon sugarRibose – 5-carbon sugar3 phosphate groups3 phosphate groupsThe phosphate groups are The phosphate groups are charged particlescharged particles

ATPATP It requires a lot of energy to It requires a lot of energy to

force the phosphate groups force the phosphate groups to bond because of their to bond because of their same chargessame charges

All that energy becomes All that energy becomes available when the bonds available when the bonds are broken between the are broken between the phosphatesphosphates

ATPATP

When ATP has the last When ATP has the last phosphate broken off to phosphate broken off to release the energy, it release the energy, it becomes ADP becomes ADP (adenosine (adenosine diphosphate)diphosphate)

PhotosynthesisPhotosynthesis

Trapping the Sun’s EnergyTrapping the Sun’s Energy

The Photosynthesis The Photosynthesis EquationEquation

Word equation:Word equation: Carbon dioxide + waterCarbon dioxide + water lightlight>>

glucose + oxygenglucose + oxygen Chemical equation:Chemical equation: 6 CO6 CO22 + 6 H + 6 H22OO lightlight>>

CC66HH1212OO66 + 6 O + 6 O22

Light and PigmentsLight and Pigments

Photosynthesis requires light-Photosynthesis requires light-catching pigmentscatching pigments

Chlorophyll Chlorophyll Accessory pigments include: Accessory pigments include:

xanthophyll and beta carotinexanthophyll and beta carotine

Reactions in the Reactions in the ChloroplastChloroplast ThylakoidsThylakoids – membrane sacs – membrane sacs

that contain clusters of pigment that contain clusters of pigment molecules called photosystemsmolecules called photosystems

GranaGrana- stacks of thylakoids- stacks of thylakoids StromaStroma – area outside the – area outside the

thylakoidthylakoid

Light dependentLight dependent reactions reactions happen in the happen in the thylakoidsthylakoids (that’s where the light-(that’s where the light-catching pigments are)catching pigments are)

Light independentLight independent reactions happen in the reactions happen in the stromastroma

NADPHNADPH

The process of capturing The process of capturing sunlightsunlight results in the results in the formation of high energy formation of high energy electrons electrons

These These high energy electronshigh energy electrons require special carrier require special carrier moleculesmolecules

NADPHNADPH

NADPNADP++ is a carrier molecule. is a carrier molecule.- nicotinamide adenine - nicotinamide adenine dinucleotide phosphatedinucleotide phosphate

• - - acceptsaccepts a pair of high energy a pair of high energy electrons along with a hydrogen electrons along with a hydrogen ion: Hion: H++

- - creates NADPHcreates NADPH

Light Dependent Light Dependent ReactionsReactions

Requires LightRequires LightTurns Turns ADPADP and and NADPNADP++ into into

the high energy carriers the high energy carriers ATPATP and NADPH and NADPH

How does it work?How does it work? Light is first absorbed by Light is first absorbed by

pigmentspigments in Photosystem II in Photosystem IIAbsorbed light increases Absorbed light increases

energy in energy in electronselectrons which are which are passed to electron transport passed to electron transport chainchain

New electrons for New electrons for chlorophyllchlorophyll come from watercome from water

High energy electrons travel High energy electrons travel from Photosystem II to from Photosystem II to Photosystem I on the Electron Photosystem I on the Electron Transport ChainTransport Chain

Electron Transport Chain Electron Transport Chain drives drives transporttransport HH++ across the across the membrane of the thylakoidmembrane of the thylakoid

Photosystem I reenergizes high Photosystem I reenergizes high energy electrons and energy electrons and transferstransfers them to NADPthem to NADP++ which becomes which becomes NADPH after picking up HNADPH after picking up H++

Process creates a charge Process creates a charge difference across the difference across the thylakoidthylakoid membranes; restoring the membranes; restoring the charge balance drives ATP charge balance drives ATP creationcreation

HH+ + concentration is higher concentration is higher on one side of the on one side of the thylakoid membrane than thylakoid membrane than the otherthe other

Facilitated diffusion Facilitated diffusion happens to correct charge happens to correct charge imbalanceimbalance

ATP synthaseATP synthase helps with helps with facilitated diffusion of facilitated diffusion of hydrogen ions, but uses hydrogen ions, but uses their passage to create their passage to create ATPATP

Drives ATP synthesisDrives ATP synthesis

The Calvin CycleThe Calvin Cycle ATP and NADPH are not ATP and NADPH are not stablestable

enough to store energy for longenough to store energy for long The Calvin Cycle converts less The Calvin Cycle converts less

stablestable, high energy molecules , high energy molecules into high energy sugars into high energy sugars (glucose)(glucose)

Calvin Cycle is Calvin Cycle is light-light-independentindependent

How Does it Work?How Does it Work?66 carbon dioxide molecules carbon dioxide molecules

combine with 6 5-carbon combine with 6 5-carbon molecules molecules

combine with six combine with six 5-carbon5-carbon molecules which molecules which splitsplit creating creating twelve 3 carbon moleculestwelve 3 carbon molecules

33 carbon molecules are then carbon molecules are then converted to high converted to high energyenergy form form using the energy from ATP using the energy from ATP and NADPHand NADPH

22 of the twelve 3-carbon of the twelve 3-carbon compounds are compounds are convertedconverted to to similar molecules and similar molecules and combined to form a 6-carbon combined to form a 6-carbon sugarsugar

The remaining The remaining tenten 3-carbon 3-carbon compounds are compounds are recombinedrecombined into into 5-carbon compounds and re-5-carbon compounds and re-enter the cycleenter the cycle

Plants use 6-carbon Plants use 6-carbon sugarssugars for for energy for growth and repair, energy for growth and repair, and to construct complex and to construct complex carbohydrates like cellulosecarbohydrates like cellulose

Chap 9.2: Chap 9.2: Photosynthesis Photosynthesis (summary)(summary) Photosynthesis happens in 2 Photosynthesis happens in 2

stages; light-dependant reactions, stages; light-dependant reactions, and light-independent reactions in and light-independent reactions in the chloroplast.the chloroplast.

Light-dependant reactions - energy Light-dependant reactions - energy is passed down the electron-is passed down the electron-transport chain to form ATPtransport chain to form ATP

Photolysis of water releases OPhotolysis of water releases O22 and restores electrons for electron and restores electrons for electron transport chain. NADPH forms for transport chain. NADPH forms for use in light-independent rxs.use in light-independent rxs.

Light-independent reactions Light-independent reactions (Calvin Cycle) uses CO(Calvin Cycle) uses CO22 to form to form sugar in the stroma of the sugar in the stroma of the chloroplast.chloroplast.

Cellular Cellular RespirationRespiration

Chapter 9.3: Big IdeasChapter 9.3: Big Ideas

Cellular Respiration happens in Cellular Respiration happens in 3 stages: 3 stages: glycolysis, glycolysis, the citric acid cycle(Krebs the citric acid cycle(Krebs cycle), cycle),

the electron transport chain.the electron transport chain.

Chapter 9.3: Big Ideas Chapter 9.3: Big Ideas (cont)(cont)

Glycolysis- breaks down Glycolysis- breaks down glucose to make pyruvic glucose to make pyruvic acid and ATP to start the acid and ATP to start the respiration process.respiration process.

Chapter 9.3: Big Ideas Chapter 9.3: Big Ideas (cont)(cont)

Citric Acid cycle- breaks down Citric Acid cycle- breaks down Acetyl-CoA and forms ATP and Acetyl-CoA and forms ATP and CO2 in the MitchondriaCO2 in the Mitchondria

Electron Transport Chain- Electron Transport Chain- Produces ATP and H2OProduces ATP and H2O

Cellular Resp. OverviewCellular Resp. Overview

• Process used by cells to Process used by cells to release energy from foods release energy from foods using oxygenusing oxygen

• oxygen + glucose oxygen + glucose carbon carbon dioxide + water + energydioxide + water + energy

Cellular Resp. Overview Cellular Resp. Overview (cont)(cont)

• 6 O6 O22 + C + C66HH1212OO66 6 CO 6 CO22 + 6 + 6

HH22O + EnergyO + Energy

• Involves glycolysis and the Involves glycolysis and the Krebs or Citric Acid CycleKrebs or Citric Acid Cycle

GlycolysisGlycolysis

Basically: one glucose (6-Basically: one glucose (6-carbon sugar) is split into 2 carbon sugar) is split into 2 pyruvic acid (3-carbon pyruvic acid (3-carbon molecules)molecules)

2 ATP are needed to start 2 ATP are needed to start process, but 4 ATP are process, but 4 ATP are producedproduced

Glycolysis (cont)Glycolysis (cont)

NADNAD++ is another high energy is another high energy electron pair acceptorelectron pair acceptor

2 NADH are created by 2 NADH are created by glycolysis; can be used to glycolysis; can be used to make ATPmake ATP

No oxygen neededNo oxygen needed

The Krebs Cycle and The Krebs Cycle and Electron Transport Electron Transport

Aerobic part of cellular Aerobic part of cellular respirationrespiration

The Krebs cycle breaks The Krebs cycle breaks pyruvic acid into carbon pyruvic acid into carbon dioxide and water using dioxide and water using oxygen oxygen

The Krebs CycleThe Krebs Cyclea.k.a. Citric Acid Cyclea.k.a. Citric Acid Cycle

Pyruvic acid enters Pyruvic acid enters mitochondrion from the mitochondrion from the cytoplasmcytoplasm

1 carbon is broken off as 1 carbon is broken off as carbon dioxide; 2-carbon carbon dioxide; 2-carbon compound is leftcompound is left

2-carbon compound binds with 2-carbon compound binds with coenzyme A to form acetyl-coenzyme A to form acetyl-coenzyme A (acetyl-coA)coenzyme A (acetyl-coA)

Acetyl-coA attaches to a 4-Acetyl-coA attaches to a 4-carbon compound to form citric carbon compound to form citric acid ( hence the name Citric Acid acid ( hence the name Citric Acid Cycle )Cycle )

Through various intermediate Through various intermediate stages; 2 more carbons are stages; 2 more carbons are released as carbon dioxidereleased as carbon dioxide

A 4-carbon compound is left; this A 4-carbon compound is left; this will attach to the next acetyl-coA will attach to the next acetyl-coA and the cycle starts overand the cycle starts over

Electron TransportElectron Transport

A series of molecules that A series of molecules that uses high-energy electrons uses high-energy electrons to convert ADP into ATPto convert ADP into ATP

Electron TransportElectron Transport

High energy electrons are High energy electrons are passed along the electron passed along the electron transport chain; at the end, transport chain; at the end, there is usually an enzyme there is usually an enzyme that transfers the electrons to that transfers the electrons to oxygen and hydrogen to form oxygen and hydrogen to form waterwater

Every time a pair of electrons Every time a pair of electrons travels down the chain, travels down the chain, their their energy is used to send Henergy is used to send H++ across across the membrane. the membrane.

This creates an area of high HThis creates an area of high H++ concentration and an area of low concentration and an area of low HH++ concentration concentration

Facilitated diffusion occurs to try Facilitated diffusion occurs to try to bring to bring HH++ concentrations to concentrations to equilibriumequilibrium

The carrier molecule is ATP The carrier molecule is ATP synthase which make an ATP for synthase which make an ATP for every Hevery H++ that goes across the that goes across the membranemembrane

1 pair of high energy electrons = 3 1 pair of high energy electrons = 3 ATPATP

The TotalsThe Totals

Glycolysis = Glycolysis = 2 ATP2 ATP Krebs/Electron Trans=Krebs/Electron Trans=34ATP34ATP TotalTotal 36 ATP36 ATP

FermentationFermentation

Anaerobic way to process Anaerobic way to process food to get energyfood to get energy

Everything starts with Everything starts with GlycolysisGlycolysis

Alcoholic FermentationAlcoholic Fermentation

Pyruvic acid + NADH Pyruvic acid + NADH alcohol + COalcohol + CO22 + NAD + NAD++

Yeast works on an Yeast works on an alcoholic fermentation alcoholic fermentation systemsystem

Lactic Acid FermentationLactic Acid Fermentation

Pyruvic acid + NADH Pyruvic acid + NADH lactic lactic acid + NADacid + NAD++

Muscle cells can build up lactic Muscle cells can build up lactic acid when they are forced to acid when they are forced to work without enough of an work without enough of an oxygen supplyoxygen supply

Photosynthesis and Photosynthesis and Cellular RespirationCellular Respiration

PhotosynthesisPhotosynthesis CellularCellular RespirationRespiration

FunctionFunction Energy storageEnergy storage Energy releaseEnergy release

LocationLocation ChloroplastsChloroplasts MitochondriaMitochondria

ReactantsReactants COCO22 and H and H

22OO CC66HH1212OO66 and O and O22

ProductsProducts CC66HH1212OO66 and O and O22 COCO

22 and H and H22OO

EquationEquation 6 CO6 CO22 + 6 H + 6 H

22O -> O ->

CC66HH1212OO66 + 6O + 6O22

6O6O22 + C + C

66HH1212OO66 -> ->

6 CO6 CO22 + 6 H + 6 H

22OO