tracing the atoms through the process of photosynthesis - simple

1. Light Reactions
and the Calvin
Cycle
Tracing atoms through the
process of photosynthesis

2. The Law of the Conservation of
Matter
 Matter cannot be created or destroyed
 Matter (atoms) can only be rearranged into
new molecules

4. The Light Reactions
 H2O
enters
 O2 exits
 ATP and
NADPH
energy
carriers
are made

5. Let’s follow the
atoms on their
journey through
photosynthesis
Starting with…H2O

6. What happens to the H2O?
Oxygen in H2O
splits off and
released from leaf
O2

7. Think-pear-share
What is the
significance of
this step?

8. What happens to the
hydrogens?
 Electrons from
hydrogen given to
chlorophyll
Draw this
Hydrogen

9. Think-pear-share
What is chlorophyll?
What can it do?

10. 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+

11. Think-pear-share
Why doesn’t the plant just
stop here? The light energy
is trapped as chemical
energy? Why bother
making glucose? What is
glucose good for?

12. 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+

13. Protons
 Protons cannot cross the membrane
because they have a charge
 When they move by facilitated diffusion,
ATP is made

14. Think-pear-share
 Why can’t hydrogen protons
cross the membrane of the
thylakoid?
 What is it about membranes that
prevents them from moving?

15. So…
H2O
Released
Protons
used to
make ATP
Electrons
to NADP+
Draw this

17. Calvin
Cycle
 CO2 enters
the leaf
 ATP and
NADPH
power the
cycle
 Glucose is
made

18. Let’s follow the
atoms on their
journey through
photosynthesis
ending with…CO2

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

20. What happens to the CO2?
CO2 enters the
leaf
ATP powers the
transfer of high
energy electrons
to CO2 (and H2O)
to make C6H12O6

21. Think-pear-
share
 Where did those high energy electrons come
from originally?
 How did they get to be so high in energy?

22. So…
H2OCO2
C6H12O6
Draw this

23. 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.