PhotosynthesisPhotosynthesis

The “Rodney Dangerfield” The “Rodney Dangerfield” process of Biologyprocess of Biology

The Process that Feeds the BiosphereThe Process that Feeds the Biosphere

Q: Where does photosynthesis Q: Where does photosynthesis occur?occur?

Photosynthetic Photosynthetic ORGANISMS ORGANISMS include…..include…..

……plants, algae, protists, plants, algae, protists, cyanobacteriacyanobacteria

Where does photosynthesis occur?Where does photosynthesis occur?

(Assume plants)(Assume plants)The The ORGANORGAN of of photosynthesis photosynthesis is….is….

Leaf: ORGAN of photosynthesisLeaf: ORGAN of photosynthesis

Leaf: ORGAN of photosynthesisLeaf: ORGAN of photosynthesis

Let’s take a closer look at a Let’s take a closer look at a chlorenchyma (mesophyll) cell…chlorenchyma (mesophyll) cell…

Introducing the Introducing the OrganelleOrganelle of of PhotosynthesisPhotosynthesis

The ChloroplastThe Chloroplast

Remember this?Remember this?

HumanHuman OrganismOrganism RedbudRedbud

OrganOrgan

TissueTissue

CellCell

OrganelleOrganelle

MoleculeMolecule

Possible Answers:Possible Answers:

HumanHuman OrganismOrganism RedbudRedbud

BrainBrain OrganOrgan

NervousNervous TissueTissue

NeuronNeuron CellCell

NucleusNucleus OrganelleOrganelle

DNADNA MoleculeMolecule

Levels of OrganizationLevels of Organization

HumanHuman OrganismOrganism RedbudRedbud

BrainBrain OrganOrgan LeafLeaf

NervousNervous TissueTissue ChlorenchymaChlorenchyma

NeuronNeuron CellCell ChlorenchymaChlorenchyma

NucleusNucleus OrganelleOrganelle ChloroplastChloroplast

DNADNA MoleculeMolecule ChlorophyllChlorophyll

Equations of PhotosynthesisEquations of Photosynthesis

Complete:

6 CO2 + 12 H2O + Light energy C6H12O6 + 6 O2 + 6 H2 O

Net:6 CO2 + 6 H2O + Light energy C6H12O6 + 6 O2

Photosynthesis & Cellular Photosynthesis & Cellular RespirationRespiration

PhotosynthesisPhotosynthesis::6 CO2 + 6 H2O + Light energy C6H12O6 + 6 O2

Remember:First Law of Thermodynamics

Redox Reactions

Cellular Respiration:

C6H12O6 + 6O2 6CO2 + 6H2O + ATP Energy

Purpose of Photosynthesis?Purpose of Photosynthesis?

Parts of PhotosynthesisParts of Photosynthesis

Photosynthesis consists of two Photosynthesis consists of two processes:processes:

1.1. The Light reactionsThe Light reactions

2.2. The Calvin cycleThe Calvin cycle

Parts of PhotosynthesisParts of Photosynthesis

1.1. The Light reactionsThe Light reactions

Purpose: To trap photons of light energy Purpose: To trap photons of light energy and temporarily store in in molecules of and temporarily store in in molecules of ATP and NADPHATP and NADPH

Location: surface of the Thylakoid disksLocation: surface of the Thylakoid disks

Note Thyllakoid Disk:Note Thyllakoid Disk:

Parts of PhotosynthesisParts of Photosynthesis

2. The Calvin cycle (aka) dark reactions:2. The Calvin cycle (aka) dark reactions:

Purpose: To remove the trapped energy Purpose: To remove the trapped energy from temporary storage, combine from temporary storage, combine with carbon dioxide, to make sugar!with carbon dioxide, to make sugar!

Location: Stroma of chloroplastLocation: Stroma of chloroplast

Note stroma:Note stroma:

Chlorophyll:Chlorophyll: Key molecule Key molecule (pigment) of photosynthesis(pigment) of photosynthesis

The above image is from http://www.nyu.edu:80/pages/mathmol/library/photo.

Key VocabularyKey Vocabulary

Pigment -Pigment - Photosystem –Photosystem – photonphoton

Nature of LightNature of Light

Steps of Light ReactionsSteps of Light Reactions

See handout (& remember purpose)See handout (& remember purpose) Note: “reaction center”Note: “reaction center”

What happens when chlorophyll What happens when chlorophyll absorbs light?absorbs light?

Light Reactions!Light Reactions!

Understanding checkUnderstanding check(Light Reactions)(Light Reactions)

Where is energy of photons of light?Where is energy of photons of light?

Why do plants need water (during Why do plants need water (during photosynthesis)?photosynthesis)?

How has oxygen been produced?How has oxygen been produced?

Has carbon dioxide been used?Has carbon dioxide been used?

Calvin CycleCalvin Cycle

Understanding CheckUnderstanding Check(Calvin Cycle)(Calvin Cycle)

Which products of the light reactions Which products of the light reactions are necessary to drive the Calvin are necessary to drive the Calvin cycle?cycle?

What is the most abundant protein What is the most abundant protein on Earth? What does it do?on Earth? What does it do?(Aside: What is the most abundant carbohydrate (Aside: What is the most abundant carbohydrate on Earth?)on Earth?)

Understanding CheckUnderstanding Check(General)(General)

Do plants use oxygen? Why or why Do plants use oxygen? Why or why not?not?

Do plants produce both oxygen & Do plants produce both oxygen & carbon dioxide?carbon dioxide?

Big picture #1:Big picture #1:

Indicate “light” or “Calvin” for each Indicate “light” or “Calvin” for each reactant and product:reactant and product:

CO2 + H2O + Light E C6H12O6 + O2 (dark) (light) (light) (dark) (light)

Big picture #2:Big picture #2:

Indicate how each enters or leaves the Indicate how each enters or leaves the plant: plant:

CO2 + H2O + Light E C6H12O6 + O2

Big Picture #3:Big Picture #3:

Importance of PhotosynthesisImportance of Photosynthesis(3 ways to view photosynthesis……..)(3 ways to view photosynthesis……..)

1) 1) Traps energyTraps energy for plant and for entire for plant and for entire ecosystemecosystem(Remember: Plants are (Remember: Plants are autotrophs/producersautotrophs/producers

2) 2) C-fixationC-fixation for plant and for entire for plant and for entire ecosystemecosystem(Remember: Plants are (Remember: Plants are autotrophs/producers)autotrophs/producers)

Big Picture #3Big Picture #3

Importance of PhotosynthesisImportance of Photosynthesis

3) Produces 3) Produces oxygenoxygen for entire planet! for entire planet!

Note: This is an accident!Note: This is an accident!in purple bacteria:CO2 + H2S + Light E C6H12O6 + S

Question: What organisms USE oxygen?Question: What organisms USE oxygen?

For what purpose?For what purpose?

Evolutionary PerspectiveEvolutionary Perspective

Earth formed about 4.5 byaEarth formed about 4.5 bya

Original atmosphere was anaerobic (no Original atmosphere was anaerobic (no oxygen)oxygen)

Cyanobacteria (first photosynthesizers) Cyanobacteria (first photosynthesizers) released oxygenreleased oxygen

Build-up of oxygen allowed eukaryotes Build-up of oxygen allowed eukaryotes and multi-cellular organisms to flourish!and multi-cellular organisms to flourish!

Evolutionary Perspective (cont)Evolutionary Perspective (cont)

Oxygen build-up in atmosphere also Oxygen build-up in atmosphere also allowed for the formation of OZONE!allowed for the formation of OZONE!

3 03 022 2 0 2 03 3

Why is ozone important?Why is ozone important?

Big Picture #4Big Picture #4

Can you list SIX similarities and SIX Can you list SIX similarities and SIX differences/opposites between differences/opposites between cellular respiration and cellular respiration and photosynthesis?photosynthesis?

Big Picture #4 (cont) Big Picture #4 (cont)

Similarities between mitochondria & Similarities between mitochondria & chloroplast:chloroplast:

Both have internal and external Both have internal and external membranemembrane

Both believed to have originated Both believed to have originated from once free-living bacteria cellsfrom once free-living bacteria cells(Endosymbiotic Theory)(Endosymbiotic Theory)

Both use chemiosmosis to generate Both use chemiosmosis to generate ATPATP

Chloroplasts and MitochondriaChloroplasts and Mitochondria• Generate ATP by the same basic Generate ATP by the same basic

mechanism: mechanism: ChemiosmosisChemiosmosis• Compare/Contrast:Compare/Contrast:

2. Movement of H+ (between what 2. Movement of H+ (between what spaces, what direction?)spaces, what direction?)