Photosynthesis
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Photosynthesis. Photosynthesis. Photosynthesis. Reduction. Oxidation. Oxidation. Reduction. Photosynthesis. How is light energy quantified? Light energy is a form of electromagnetic radiation

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Photosynthesis

Reduction

Oxidation

Oxidation

Reduction


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Photosynthesis

How is light energy quantified?

Light energy is a form of electromagnetic radiation

Electromagnetic radiation can be described in terms of a stream of mass-less particles, each traveling in a wave-like pattern and moving at the speed of light.

Each mass-less particle contains a certain amount (or bundle) of energy. Each bundle of energy is called a photon, and all electromagnetic radiation consists of these photons.

The only difference between the various types of electromagnetic radiation is the amount of energy found in the photons.


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Photosynthesis

Wavelength is the distance between adjacent

peaks in a series of periodic waves



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Photosynthesis

Visible light: 390nm –760nm.

nm = nanometers = 10-9 m

390 nm = violets 550 nm = greens 750 nm = reds

Which color light has the most energy? Which the least?

How do we perceive color & how is it related to the wavelength of light?

Why is a plant leaf green?




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Photosynthesis

Reflectedlight

Light

Chloroplast

Absorbedlight

Transmittedlight


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What or how do these molecules convert the energy in the photons to chemical energy?

PHOTOSYNTHESIS

6 CO2 + 6 H2O + light energy C6H12O6 + 6 O2

Photosynthesis

  • Photosynthesis consists of two basic steps

  • Light dependent reactions – conversion of light energy to chemical energy

  • Light independent reactions – fixation of carbon dioxide into carbohydrates, utilizing the energy created in the light dependent reactions


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Photosynthesis photons to chemical energy?

H2O

CO2

Chloroplast

Light

NADP+

ADP+

P

LIGHTREACTIONS(in grana)

CALVINCYCLE(in stroma)

ATP

Electrons

NADPH

O2

Sugar


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Photosynthesis photons to chemical energy?


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Photosynthesis photons to chemical energy?


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Photosynthesis photons to chemical energy?

The production of ATP by chemiosmosis in photosynthesis

Thylakoidcompartment(high H+)

Light

Light

Thylakoidmembrane

Antennamolecules

Stroma(low H+)

ELECTRON TRANSPORT CHAIN

PHOTOSYSTEM II

PHOTOSYSTEM I

ATP SYNTHASE

Figure 7.9


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Photosynthesis photons to chemical energy?

What happens following the conversion of light energy to ATP & NADPH?

The Light independent reactions!

Where do these reactions occur?

What happens? The Calvin Cycle

Carbon dioxide fixed into PGAL

3GP is the precursor molecule to the 6-carbon sugar glucose


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Photosynthesis photons to chemical energy?

Details of the Calvin cycle

INPUT:

3

In a reaction catalyzed by rubisco, 3 molecules of CO2 are fixed.

CO2

Step Carbon fixation.

1

1

3

P

P

6

P

RuBP

3-PGA

6

ATP

3 ADP

Step Energy consumption and redox.

2

6 ADP +

P

CALVINCYCLE

3

ATP

2

6

4

NADPH

6 NADP+

Step Release of one molecule of PGAL.

3

5

P

6

P

PGAL

PGAL

3

Step Regeneration of RuBP.

4

Glucoseand other compounds

OUTPUT:

1

P

PGAL


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Photosynthesis photons to chemical energy?

The Calvin Cycle (aka dark reactions, light independent reactions

Begins with the fixation of CO2 to ribulose bisphosphate (5 carbon sugar) with the aid of the enzyme rubisco (ribulose bisphosphate carboxylase)

The resulting 6 carbon sugar is split into 2 3-phosphoglycerate molecules (3 carbon sugars)

They are reduced & converted to PGAL via the utilization of ATP & NADPH

Some of the PGAL is used to make glucose, the rest to regenerate ribulose bisphosphate so that the cycle can fix more carbon dioxide again


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Chapter 7 photons to chemical energy?

Photosynthesis


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Chapter 7 photons to chemical energy?

Photosynthesis


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