Energy and Photosynthesis

• What is Energy? – Ability to do work…..ughh…

• Kinetic Energy? – Energy in Action

– Examples

• Potential Energy? – Stored Energy

– Examples

• What is the Conservation of Energy?– ENERGY CANNOT BE CREATED OR DESTROYED!

Adenine Ribose 3 Phosphate groups

Adenosine Tri Phosphate (ATP)

Who uses it?

ADP and ATP

Adenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP

Photosynthesis

Goal is to capture kinetic light energy and convert it to stored Potential energy in the form of GLUCOSE

• Equation6CO2 + 6H20 C6H12O6 + 6O2

Electromagnetic Spectrum

• Light is a form of kinetic energy called Electromagnetic radiation– Travels in waves (and particles)– Different wavelengths give the energy different

properties

• Blue light has more energy than red light (its faster for a small wave to move than a long wave----think of jumping rope!)

Plants and Light

• Visible light = small part of electromagnetic spectrum

• Sunlight is a mixture of all colors of light. Each color of light has a different wavelength, and thus a different amount of energy.

• Plants only use visible wavelengths of light.

Chloroplasts

Parts of Chloroplast• Chloroplast: Site of photosynthesis in

eukaryotic cells.• Thylakoids: Disk shaped membranes

containing photosynthetic pigments. Site of light dependent reactions.

• Grana: Stacks of thylakoids.• Stroma: Fluid filled space surrounding

grana. Site of light independent reactions.

PHOTOSYNTHESIS

CalvinCycle

ADP + P

NADP+

ATP

NADPH

Light-Dependent Reactions

Light Dependent Reactions

• All the reactions of photosynthesis that are directly dependent upon light are known as the light dependent reactions.

• The light dependent reactions occur in the part of the cell known as the thylakoids (Stacks of thylakoids are known as grana.).

• Many chlorophyll molecules are found embedded into the membranes of the thylakoids.

• The purpose of the light reactions is to convert light energy into chemical energy in the form of ATP & NADPH.

• ATP & NADPH are energy carriers. – ATP carries energy

•  – NADPH carries high energy electrons and

hydrogen ions

2 Parts to Light Reactions

• Photosystem II– Happens 1st

– Part of light reactions that ultimately generates ATP molecules

• Photosystem I– Happen 2nd

– Part of light reactions that ultimately generate NADPH molelecules

How the Photosystems work• Electrons (from water) exited by particles of light

(photons)

• Exited electrons used to generate ATP and NADPH

• See handout for how it works.• Big idea is knowing what each photosystem does.

• ALL ABOUT TRANSFERING ENERGY OVER TO CALVIN CYCLE!!!

Light Photon

Light Photon

Photosystem II

Photosystem I

H2O

O2waste

Electrons removed from H20 are exited in Photosystem II. The electron flow down the transport chain provides energy for the transport of hydrogen ions (creating concentration gradient which ultimately drive the production of ATP.

Ele

ctro

ns E

xite

d

ADP + PATP

Ele

ctro

ns E

xite

d

e-

e-

e-

e-

e-

e-

e-

e-

(NADP+) picks up high energy electrons

NADPH

In Photosystem I, the electrons get energized by a photon of light (again) and travel down another transport chain where they become part of An NADPH molecule.

Chlorophyll

Chlorophyll

e-

e-

H+ (from water molecule)

Actively transported across thylakoid membrane

H+H+

H+

H+H+

H+

H+

H+

H+

H+

H+

ATP Synthase

H+

H+

H+

Thylakoid

membrane

Thylakoid

membrane

Thylakoid

membrane

The light reactions and chemiosmosis

Calvin Cycle (aka Dark Reactions aka light independent reactions)

• All reactions of photosynthesis not directly dependent upon light are known as the light independent reactions. They occur whether there is light present or not.

• The light independent reactions occur in the

part of the chloroplast known as the stroma.• The purpose of the light independent

reactions is to take the energy from ATP and energized electrons and hydrogen ions from NADPH and add them to CO2 to make glucose or sugar.

• The purpose of the light independent reactions (Calvin cycles) is to take the energy from ATP and energized electrons and hydrogen ions from NADPH and add them to CO2 to make glucose or sugar.