PHOTOSYNTHESIS

AUTOTROPHS

Auto = self Troph = eating Organisms that can produce their own food

(energy) from inorganic materials (sunlight)

HETEROTROPH

Hetero = other Troph = eating Organisms that cannot make its own food.

Requires organic compounds (other organisms) for its principle source of food.

CHEMICAL ENERGY AND ATP

All cells use chemical energy carried by ATP-Adenosine triphosphate.

Cells use ATP for functions such as building molecules and moving material through active transport.

ATP

The energy carried by ATP is released when a phosphate group is removed from the molecule.

ATP become ADP (Adenosine diphosphate)

ADP can become ATP again through a series of chemical reactions.

ATP

ATP is produced during the breakdown of carbon-based molecules.

Different foods provide different amounts of ATP.

Carbohydrates (glucose) can make ~ 36 molecules of ATP

Lipids can make ~ 146 molecules

SPECIAL CREATURES

Some organisms do not need sunlight and photosynthesis as a source of energy. Some organisms live near

cracks in the ocean and never see sunlight

Chemosynthesis Process by which some

organisms use chemical energy instead of light energy to make energy-storing carbon-based molecules

PHOTOSYNTHETIC ORGANISMS ARE PRODUCERS.

• Producers– Produce the chemical

energy for themselves and for other organisms.

• Photosynthesis– A process that captures

energy from sunlight to make sugars that store chemical energy.

• Chlorophyll– A molecule in chloroplasts

that absorb some of the energy in visible light

PHOTOSYNTHESIS IN CHLOROPLASTS

Chloroplasts are in leaf cells

Grana are stacks of coin-shaped membrane-enclosed compartments called thylakoids. The membranes of

thylakoids contain chlorophyll and protein

Stroma is the fluid that surrounds the grana inside the chloroplast.

PHOTOSYNTHESIS IN CHLOROPLASTS

Light-dependent reactions 1. chlorophyll absorbs

light. 2. energy is transferred to

molecules that carry energy (ATP).

Light-independent reactions 3. CO2 is added to build

larger molecules. Energy from the light-dependent reactions is used.

4. A molecule of simple sugar is formed. C6H12O6 (glucose)

FIRST STAGE: LIGHT-DEPENDENT REACTION

Capture and transfer energy. There are two photosystems involved:

photosystem II and photosystem I

LIGHT-DEPENDENT REACTION

Chlorophyll and other light-absorbing molecules capture energy from sunlight.

Water molecules are broken down into hydrogen ions, electrons, and oxygen gas (waste)

Sugars are NOT MADE during this part of photosynthesis

Day 1

LIGHT DEPENDENT REACTION: PHOTOSYSTEM II AND ELECTRON TRANSPORT

• Chlorophyll and other light absorbing molecules absorb energy from sunlight and that energy is transferred into chloropyll.

• The energy is then transferred to electrons.– 1. Energy is absorbed in sunlight

• High energy electrons leave the chorophyll and enter the electron transport chain (a series of proteins in the thylakoid)

– 2. Water molecules split– 3. Hydrogen ions transported

LIGHT DEPENDENT REACTION: PHOTOSYSTEM I AND ENERGY-CARRYING MOLECULES

Chlorophyll and other light-absorbing molecules absorb sunlight and add it to the electrons from photosystem II 4. Energy is absorbed

from sunlight. Electrons are energized.

5. NADPH produced. In photosynthesis NADPH

functions like ATP. The molecules of NADPH go

to light-independent reactions.

ATP PRODUCTION

Final part of the light-reaction. 6. Hydrogen ion diffusion

H+ ions flow through the thylakoid. 7. ATP produced

ATP synthase take the ions as they flow and makes ATP by adding phosphate groups to ADP.

LIGHT DEPENDENT REACTION: PHOTOSYSTEM II AND PHOTOSYSTEM I

SUMMARY OF LIGHT-DEPENDENT REACTIONS

PRODUCTS ARE: NADPH

Used later to make sugar. ATP

Used later to make sugar. Oxygen

Given off as a waste.

2ND STAGE: LIGHT INDEPENDENT REACTION

Uses energy from the first stage to make sugar.

Light-independent reactions take place ANY time that energy is available (it doesn’t need sunlight). Light-independent

reactions use the NADPH and ATP made during the light-dependent reactions to make sugar.

THE CALVIN CYCLE

Uses the NADPH and ATP from the light-dependent reaction, and CO2 from the atmosphere to make simple sugars.

THE CALVIN CYCLE

1. Carbon dioxide added. CO2 molecules are

added to five-carbon molecules already in the Calvin Cycle.

Six-carbon molecules are formed.

2. Three-carbon molecules formed. ATP and NADPH is used

to split the six-carbon molecules into two three-carbon molecules.

THE CALVIN CYCLE

3. Three-carbon molecules exit. Most of the three-carbon

molecules will stay IN the Calvin Cycle.

ONE high energy three-carbon molecule will leave the cycle.

When TWO three-carbon molecules leave the cycle, they will bond together to build a six-carbon sugar molecule. Glucose (C6H12O6)

THE CALVIN CYCLE

4. Three-carbon molecules recycled. Energy from ATP is

used to change the three-carbon molecules that stayed in the cycle to five-carbon molecules.

These five-carbon molecules stay in the Calvin Cycle.

They are added to new CO2 molecules that enter the cycle.

THE CALVIN CYCLE

SUMMARY OF LIGHT-INDEPENDENT REACTIONS

PRODUCTS ARE: Glucose

Used to store energy. NADP+

Return to the light-dependent reaction. Will be changed into

NADPH there. ADP

Return to the light-dependent reaction. Will be changed into

ATP there.

FUNCTIONS OF PHOTOSYNTHESIS

Provides material for plant growth and development.

Simple sugars are bonded together to form complex sugars like cellulose and starch. Starches store energy for the

plant. Cellulose is a major component of

the cell wall. Helps regulate the Earth’s

environment. Removes CO2 from the

atmosphere.

PHOTOSYNTHETIC EQUATION

6CO2 + 6H2O C6H12O6 + 6O2

Light Dependent Reactions Includes

Photosystem II Electron Transport

Chain Photosystem I

Light Independent Reactions Includes the

Calvin Cycle

PHOTOSYNTHETIC EQUATION