Photosynthesis and Cellular Respiration Notes New 1228089552907949 8

8/8/2019 Photosynthesis and Cellular Respiration Notes New 1228089552907949 8

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Photosynthesis and Cellular

Respiration


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Trapping the Suns Energy

The process by whichplants capture energyfrom the sun to build carbohydrates throughchemical pathways is called photosynthesisSolar energy converts water and carbon dioxide into

chemical energy stored in simple sugars

The simple sugar that photosynthesis produces

is glucosewhich the plant uses to store energy. The equation that represents photosynthesis is:

6CO2 + 6H2O C6H12O6 + 6O2

Solar

energy


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Chapter6

Comparing Autotrophs andHeterotrophs

Section 1 The Light Reactions

Visual Concept

Click below to watch the Visual Concept.


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Phases of Photosynthesis

Photosynthesis requires energy from the sun,but the sun is not available 24 hours a day.

Photosynthesis must occur in two phasesLight-dependent Reactions (light reactions)

Convert light energy into chemical energy (ATP andNADPH)

Light-independent Reactions (dark reactions) Uses theATP and NADPH from the light-dependent

reactions to build glucose

6CO2 + 6H2O C6H12O6 + 6O2

Solar

energy


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The Role of Chloroplasts and Pigments

Photosynthesis takes place inthe chloroplasts

Light-dependent reactions

take place in the membranesof the thylakoid disks(contain chlorophyll)

Light-independent reactions

take place in the stroma(thick fluid that forms theframework of a chloroplast)


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The Role of Chloroplasts and Pigments

The thylakoid membranes contain thepigments thatcan absorb certain wavelengths of sunlight.

The most common pigment in thechloroplasts is chlorophyll.

Chlorophyll a and b absorb mostwavelengths of lightexcept for green. Green is reflected making the plantsappear green.

In the fall, plants reabsorb chlorophyll leaving

other pigments that reflect other wavelengthsof light making the leaves appear red, yellow,or orange.


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Chapter6

Spectrum of Light and PlantPigments

Section 1 The Light Reactions

Visual Concept



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Light-dependent Reactions

Sunlight strikes the chlorophyll molecules in thethylakoid membrane.

Light energy is transferred to electrons

The electrons become highlyenergized and are passeddown an Electron Transport Chain


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The Electron Transport Chain is a series ofproteins inthe thylakoid membrane

As the electrons are transferred from one protein to

another, some energy is releasedwhich

helps join ADP and Phosphate to formATP

Pump hydrogen ions into the center of the thylakoid disk tojoin H+ and NADP+ formingNADPH (electron carrier)

ATP and NADPH will be used during the light-independentreactions


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The electrons excited by the light energy that passeddown the electron transport chain and left withNADPH need to be replaced so the reaction can

happen again. To replace those electrons, awater molecule is split

(photolysis), sending electrons back to the chlorophylland releasingOxygen and Hydrogen ions into the

atmosphere this supplies the oxygen that we breathe

Photolysis


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Solar Energy absorbed

by chloroplasts

NADPH released

Oxygen released ATP Released

Products of Light Reactions(ATP and NADPH) fuel thedark reactions


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Light-independent Reactions

The second phase of photosynthesis does not

require light and is called the Calvin Cycle.

T

he Calvin Cycle occurs in the stroma of thechloroplast.

The Calvin Cycle uses theATP and NADPH

that was built during the light-dependentreactions


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The Calvin Cycle

Uses Carbon Dioxidefrom the air

Uses ATP and

NADPH fromlight reactions

Builds a glucose molecule

Uses anotherATPto replenish RuBP


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Photosynthesis Equation

6CO2 + 6H2O C6H12O6 + 6O2

Carbon Dioxidefrom the air Used in the

Calvin Cycleduring the Dark

Reactions Water Split during

Photolysis in the

Light Reactions

Glucose Made inthe Calvin Cycleduring the Dark

Reactions

Oxygen ReleasedduringPhotolysis

in the LightReactions

Light Energy

chlorophyll

Plants can use this glucose molecule for energy duringCellular Respiration. Plants canalso convert this glucose molecule into other organic compounds such asproteins and

fats/lipids or other carbohydrates like starch and cellulose


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3 Factors that Affect Photosynthesis

Carbon Dioxide (CO2)

Without CO2, the plant would not have one of theraw materials needed in the photosynthesis equation

CO2 is used in the first step of the Calvin Cycle

Temperature

The temperature must be in the appropriate range

for the plant in order for photosynthesis to properlyoccur


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3 Factors that Affect Photosynthesis

Intensity of Light

If the intensity of light is lower, the available energyfor photosynthesis is lower.

In a greenhouse, if the light source is further away,intensity is lower and less photosynthesis can occur

If light is not available at all, the light-dependent reactionscannot occur (nor can they provide the materials used in

the light-independent reactions)


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Chapter6

Environmental Influences onPhotosynthesis

Section 2 The Calvin Cycle

Visual Concept



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Cellular Respiration

Cellular Respiration: Process by which mitochondriabreak down food molecules to produceATP inplantsand animals

Nutrients + oxygen water + ATP + CO2 Changes organic chemical energy (glucose) into

inorganic chemical energy (ATP) There are three stages of Cellular Respiration

Glycolysis

Anaerobic does not require oxygen Citric Acid (Krebs) Cycle

Aerobic does require oxygen

Electron Transport Chain Aerobic does require oxygen


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Glycolysis

Glycolysis: Breaks down glucose into two molecules ofpyruvic acid (a colorless acid formed as an important intermediate inmetabolism or fermentation)

This reaction uses enzymes and takes place in the

cytoplasm of the cell (anaerobic reaction) Produces

2 pyruvic acid molecules (used in the next step ofCellularRespiration)

2 ATP molecules (energy the cell can use)

2 NADH (electron carrier)


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Chapter7


Visual Concept

Glycolysis

Section 1 Glycolysis and Fermentation


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Into the Mitochondria

Before the next step of Cellular Respiration can

occur, the pyruvic acid molecules must go intothe mitochondria

The two oxygen-dependent (aerobic) reactionsare the Citric Acid Cycle (or Krebs Cycle) and

the electron transport chain

Pyruvic acid CO2 + water + ATP


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Citric Acid/Krebs Cycle (see page 138 in your book)CO2 is

released

Pyruvate from

Glycolysisfuels the cycle

CO2 is

released

ATP is

released

NADH

and

FADH2 is

released


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Electron Transport Chain

Electron Transport Chain uses the electron carriers(NADH and FADH2) to pass electrons down theprotein chain and slowly release energy that is used toformATP andwater molecules

Electron Transport Chain transfers the most energy


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Cellular Respiration

Glycolysis

Citric Acid Cycle

Electron Transport Chain

Glucose

Pyruvic

Acid

ATP

Pyruvic

Acid

CO2ATP

ATP

NADH

and FADH

NADH

and FADH

Oxygen

Water


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Cellular Respiration Equation

C6H12O6 + 6O2 6CO2 + 6H2O + energy

Water released

from

ElectronTransport

Chain

Oxygen from the

atmosphereUsed in Electron

Transport Chain

CarbonDioxide

waste

product ofthe Citric

Acid Cycle

ATP released fromGlycolysis, CitricAcid Cycle, and

Electron Transport

Chain

Between 34-36 ATP can be made with this process.

This ATP can be used by the cells for cellular metabolism.

Glucose made in

photosynthesisby plants or

consumed by

animalsUsed in

Glycolysis


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Fermentation

When oxygen is not available anaerobic

respiration, fermentation, can follow glycolysisin order to continue to produce energy.

This is not as efficient as aerobic respiration andproduces far fewer ATPs

Two types of fermentation:

Lactic acid Fermentation

Alcoholic Fermentation


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Lactic acid Fermentation

Lactic acid fermentation occurs in muscle cellsduring strenuous exercise when a lot of energyis required and oxygen is scarce (oxygen debt).

Glucose pyruvic acid lactic acid + ATP

The lactic acid is transferred from the musclecells to the liverwhere it will be converted

back intopyruvic acid The build up of lactic acid in the

muscles is what causes them tobe fatigued and sore.


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Alcoholic Fermentation

Yeast and some bacteria cells are capable of

alcoholic fermentation during which glucose isbroken down to release CO

2

and ethyl alcohol

Glucose pyruvic acid alcohol + CO2 + ATP

The bubbles formed by the CO2 make

bread rise

The alcohol releasedturns grape juice intowine


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Chapter7


Visual Concept

Comparing Aerobic and Anaerobic

Respiration

Section 1 Glycolysis and Fermentation


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Photosynthesis vs. Cellular RespirationPhotosynthesis Cellular Respiration

Stores Energy as glucose

Releases Energy in glucose

Occurs in Living Cells

Uses an Electron Transport

Chain

Occurs in Plant Cells

Occurs in Animal Cells

Releases Oxygen

Releases Carbon Dioxide

Creates Energy Neither!

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Photosynthesis and Cellular Respiration Notes New 1228089552907949 8