Light Reactions and the Calvin CycleTracing atoms through the process of photosynthesis

The Law of the Conservation of Matter Matter cannot be created or destroyed

Matter (atoms) can only be rearranged into new molecules

The Light Reactions H2O

enters O2 exits ATP and

NADPH energy carriers are made

Let’s follow the atoms on their

journey through photosynthesis

Starting with…H2O

What happens to the H2O?

Oxygen in H2O splits off and released from leaf

O2

Think-pear-shareWhat is the significance of this step?

What happens to the hydrogens? Electrons from

hydrogen given to chlorophyll

Draw this

Hydrogen

Think-pear-shareWhat is chlorophyll?

What can it do?

What happens to the hydrogens? Chlorophyll uses

light energy to bounce the electrons up to a higher energy state and give them to NADP+ to make NADPH

This traps the energy from sunlight in a chemical

NADP+

Think-pear-shareWhy doesn’t the plant

just stop here? The light energy is trapped as chemical energy? Why bother making glucose? What is glucose good for?

What happens to the hydrogens? The protons

from the hydrogens are moved into the lumen of the thylakoid

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

Protons Protons cannot cross the

membrane because they have a charge

When they move by facilitated diffusion, ATP is made

Think-pear-share Why can’t hydrogen protons

cross the membrane of the thylakoid?

What is it about membranes that prevents them from moving?

So…

H2OReleased Protons

used to make ATP

Electrons to NADP+

Draw this

Calvin Cycle

CO2 enters the leaf

ATP and NADPH power the cycle

Glucose is made

Let’s follow the atoms on their

journey through photosynthesis

ending with…CO2

Where do the atoms (carbon, hydrogen, and oxygen) in a molecule of GLUCOSE come from?

What happens to the CO2?

CO2 enters the leaf

ATP powers the transfer of high energy electrons to CO2 (and H2O) to make C6H12O6

Think-pear-share

Where did those high energy electrons come from originally?

How did they get to be so high in energy?

So…H2OCO2

C6H12O6

Draw this

The law of conservation of matter

How does the law of conservation of

matter explain how the atoms in CO2 and H2O are

used to make sugars.