Chapter 8 - PhotosynthesisChapter 8 - Photosynthesis

Overview of Overview of Photosynthesis and Photosynthesis and

RespirationRespiration

3. PHOTOSYNTHESIS3. PHOTOSYNTHESIS 5. RESPIRATION5. RESPIRATION

1. SUN1. SUN

2. LIGHT ENERGY2. LIGHT ENERGY

4. CHEMICAL ENERGY4. CHEMICAL ENERGY

6. ATP 6. ATP

(CELL ENERGY)(CELL ENERGY)

Energy Formation in CellsEnergy Formation in Cells

Energy for Life

ATP

ADP and P

Organic Compounds &

Oxygen

Carbon Dioxide & Water

Overview of Energy Overview of Energy FormationFormation

Plants use sunlight to make food Plants use sunlight to make food (Carbohydrates, sugars, etc) This is (Carbohydrates, sugars, etc) This is stored energy thoughstored energy though

Then cellular respiration occurs in the Then cellular respiration occurs in the mitochondria which takes the food and mitochondria which takes the food and breaks it down into usable energy, or breaks it down into usable energy, or ATPATP

What is ATP?What is ATP?

Adenosine Adenosine triphosphate- a triphosphate- a chemical compound chemical compound that can store and that can store and release energyrelease energy

How does ATP work?How does ATP work?

The energy in ATP lies in The energy in ATP lies in the bond between the the bond between the 2nd and 3rd phosphate2nd and 3rd phosphate

If you break the bond If you break the bond and release the and release the phosphate energy is phosphate energy is released which leaves released which leaves you with ADPyou with ADP

If you add a phosphate If you add a phosphate to ADP you store energyto ADP you store energy

Energy

Where does it occur?Where does it occur?

In plants that are able to capture sunlight In plants that are able to capture sunlight to make their own food (aka to make their own food (aka autotrophsautotrophs.).)

The actual process occurs inside a cell’s The actual process occurs inside a cell’s chloroplastschloroplasts..

What does it need?What does it need?

CARBON DIOXIDE (COCARBON DIOXIDE (CO22))

WATER  (HWATER  (H220)0)

SUNLIGHTSUNLIGHT

What happens? What happens? (photosynthesis equation)(photosynthesis equation)

6CO6CO22 ++ 6H6H22OO ++ ENERGYENERGY CC66HH1212OO66 ++ 6O6O22

Carbon Carbon DioxideDioxide

WaterWater CarbohydratesCarbohydrates

OxygenOxygenSunlightSunlight

How does happen?How does happen?

The process of photosynthesis does not The process of photosynthesis does not happen all at once. It is a very long happen all at once. It is a very long process that is broken into process that is broken into 33 stages. stages.

Stage 1 – Light ReactionsStage 1 – Light Reactions

Light is absorbed from the sun by the Light is absorbed from the sun by the chloroplasts.chloroplasts.

HH22O is taken into the cell as well.O is taken into the cell as well.

The light energy is used to split HThe light energy is used to split H220 into 0 into

3 separate parts (H, O3 separate parts (H, O22, and electrons.), and electrons.)

How does it work?How does it work?

Inside the chloroplasts are disk-shaped Inside the chloroplasts are disk-shaped structures called structures called thylakoidsthylakoids that contain that contain different pigments.different pigments.

How does it work?How does it work? PigmentsPigments do the actual absorbing of light. do the actual absorbing of light.

a) a) ChlorophyllsChlorophylls absorb red and blue light absorb red and blue light (produce green colors)(produce green colors)

b) b) CarotenoidsCarotenoids absorb other colors absorb other colors(produce yellow and orange colors)(produce yellow and orange colors)

How does it work?How does it work?

Once the sunlight is captured it is used to Once the sunlight is captured it is used to split water (Hsplit water (H220) into Hydrogen (H), 0) into Hydrogen (H),

Oxygen gas (OOxygen gas (O22), and free electrons. ), and free electrons.

Oxygen gas (OOxygen gas (O22) is free to leave the plant ) is free to leave the plant

and this is what animals use to breathe.and this is what animals use to breathe.

Stage 2 – Energy StorageStage 2 – Energy Storage

Free Free electronselectrons are passed from are passed from thylakoid to thylakoid until they reach an thylakoid to thylakoid until they reach an ADPADP molecule and turn it into an molecule and turn it into an ATPATP..

HydrogenHydrogen (H) molecules are passed (H) molecules are passed from protein to protein until they reach a from protein to protein until they reach a NADPNADP++ molecule and then they become molecule and then they become an an NADPH.NADPH.

How does it work?How does it work?

As electrons continuously get passed on As electrons continuously get passed on this process is known as the this process is known as the electron electron transport chaintransport chain. .

Stage 3 – Dark ReactionsStage 3 – Dark Reactions

The newly formed ATP and NADPH The newly formed ATP and NADPH power the formation of carbohydrates, power the formation of carbohydrates, sugars, and starches.sugars, and starches.

This is done by using COThis is done by using CO22 as the starting as the starting

material.material.

How does it work?How does it work?

Carbon Dioxide (COCarbon Dioxide (CO22) enters the cell ) enters the cell

from the atmosphere and undergoes a from the atmosphere and undergoes a process called the process called the Calvin CycleCalvin Cycle which which creates simple sugars.creates simple sugars.

Step 1Step 1

A Carbon Dioxide molecule is joined to a A Carbon Dioxide molecule is joined to a 5-carbon compound called 5-carbon compound called RuBPRuBP (ribulose bisphosphate) to create a 6-(ribulose bisphosphate) to create a 6-carbon compound.  carbon compound. 

Step 2Step 2

The newly formed 6-carbon compound The newly formed 6-carbon compound immediately splits into two 3-carbon immediately splits into two 3-carbon compounds.compounds.

Step 3Step 3

One of the new 3-carbon compounds is One of the new 3-carbon compounds is used to make the initial 5-carbon used to make the initial 5-carbon compound that originally joined to the compound that originally joined to the Carbon Dioxide.Carbon Dioxide.

Step 4Step 4

The second 3-carbon compound is used The second 3-carbon compound is used to make carbohydrates, sugars, and to make carbohydrates, sugars, and starches.starches.

Summary of StagesSummary of Stages

Things used:Things used: Things made:Things made:

Stage 1Stage 1 Light and HLight and H22OO OO22, H, and , H, and

electronselectrons

Stage 2Stage 2 H and electronsH and electrons ATP and NADPHATP and NADPH

Stage 3Stage 3 ATP, NADPH, ATP, NADPH, and COand CO22

Carbohydrates, Carbohydrates, sugars, starchessugars, starches

Factors that affect it?Factors that affect it?1)1) Light intensityLight intensity

2)2) Amount of COAmount of CO22 available available

3)3) TemperatureTemperature

If any of these factors increase the If any of these factors increase the photosynthesis process also increases photosynthesis process also increases and vice versa.and vice versa.

PhotosynthesisPhotosynthesisHH22OO COCO22

OO22 CC66HH1212OO66

Light Light ReactionReaction

Dark ReactionDark Reaction

Light is AdsorbedLight is AdsorbedBy By

ChlorophyllChlorophyll

Which splitsWhich splitswaterwater

ChloroplastChloroplast

ATP andATP andNADPHNADPH22

ADPADPNADPNADP

Calvin CycleCalvin Cycle

EnergyEnergy

Used Energy and is Used Energy and is recycled.recycled.

++

++

PhotosynthesisPhotosynthesis Capturing Energy from the SunCapturing Energy from the Sun** Using energy to make ATP and NADPHUsing energy to make ATP and NADPH** Using ATP and NADPH to make Using ATP and NADPH to make

carbohydrates, sugars, and starches carbohydrates, sugars, and starches **

** Light Dependent Reactions Light Dependent Reactions

* * Light Independent ReactionsLight Independent Reactions

(Calvin Cycle)(Calvin Cycle)

Any Questions?Any Questions?

Education is light, lack of it darkness.Education is light, lack of it darkness.--Russian Proverb--Russian Proverb

Education is the movement from Education is the movement from darkness to light.darkness to light. --Bloom--Bloom