1. Today’s Date
Objective here

2. Brainteaser
I am around long before dawn. But by lunch I am usually gone. You can see me summer, fall, and spring. I like to get on everything. But when winter winds start to blow; Burr, then it's time for me to go! What am I?

3. Lets Review What is photosynthesis?
Where does photosynthesis take place
What is the formula for photosynthesis

4. Photosynthesis means building with Light
‘synthesis’ = BUILD
‘photo’ = LIGHT
Photosynthesis means building with Light
carbon dioxide
CO2
water
H2O +
glucose
C6H12O6
oxygen O2 +
chlorophyll
 Green plants can make their own food from …6CO2 and 6H20…..…
 using energy in the form of ……light…………….
 which is absorbed by chlorophyll in the …chloroplast…...
 The end products of photosynthesis are …C6H12O6 and …6O2……….

5. Photosynthesis
Light Reactions

6. Today you will learn There are 2 parts to photosynthesis.
Where the light reactions take place.
What do the light reactions produce?
There are 3 parts to the Calvin cycle.
Where the dark reactions take place.
What the dark reactions produce?

7. Photosynthesis is divided into two sets of reactions
Light Reactions
Dark Reactions
Light Independent Reactions
Light Dependent Reactions
Calvin Cycle

8. Where do the light reactions take place?
take place within the thylakoid membranes of the chloroplasts
Thylakoid

9. What is the purpose of the light reactions?
Convert the light energy into chemical energy
The chemical energy is in the form of ATP (Adenine Triphosphate) and NADPH (nicotinamide adenine nucleotide phosphate)
Split H2O and release O2 atmosphere

10. Why make ATP and NADPH?
Energy is needed to start the chemical reaction
Chemical reaction will make sugar.

11. How is ATP and NADPH made?
The light-dependent reactions are comprised of two sets of reactions called photosystems.
Photosystems I
Photosystems II

12. Photosystem II A T P
Begins with absorption of energy (photon) by a chlorophyll molecule (Chl).
The chlorophyll molecule is raised to an excited state.
The electron lost by the chlorophyll is replaced by
the enzymatic splitting of water

13. This electron is passed down a chain of molecules called the electron transport chain or redox chain. A T P
Energy from this transfer of electrons is used to
produce ATP, leaving the electron in a low energy
state to be recharged by Photosystem I
Photosystem II

14. N A D P H Photosystem I The low energy electron from photosystem II
replaces one that in photosystem I that has
become energized and left the chlorophyll
Molecule in photosystem II.
Energy from this excited electron is exchanged
across different molecules (called carriers)
ultimately being used to convert NADP+ to
NADPH.
NADPH stores this electrical energy for use in
the light independent reactions.
Photosystem I

15. Photosystem II and Photosystem I
ATP
NADPH

17. Summary Light Reactions Make What? Occur Where? ATP NADPH Thylakoids
PS II
PS I

18. Dark Reactions
Calvin Cycle

19. Where do the dark reactions take place?
In the stroma of the chloroplast. The stroma is the juice in the chloroplast.
Stroma

20. What is the purpose of the dark reactions?
To use chemical energy to fix CO2 into glucose.
The chemical energy is ATP and NADPH that was produced in the light reactions

21. How do we make Glucose?
ATP and NADPH are used to incorporate CO2 into carbohydrate via a cyclic pathway called the Calvin-Benson cycle.
The Calvin Cycle is made up of three phases.
CO2 Fixation
Reduction
Regeneration of RuBP

23. Calvin Cycle: Step 1- CO2 Fixation
CO2 diffuses into the stroma from the surrounding cytosol. An enzyme combines the CO2 molecule with a five-carbon sugar called RuBP.
The product is a six- carbon molecule that immediately splits into 2 three molecules known as PGA.

24. Calvin Cycle: Step 2 - Reduction
PGA is converted into another three carbon molecule called PGAL in a two-step process.
First, a molecule of ATP (made during the light cycle) gives PGA a phosphate group.
Next, a NADPH (also made during the light cycle) gives PGA a proton (H+). PGA releases a phosphate group and is now PGAL.

25. Calvin Cycle: Step 3- Regeneration
In step 3, some of the PGAL is “recycled” and turned back into RuBP so that the cycle can continue.
Some of the PGAL is taken away and turned into organic compounds like sugars, lipids, and amino acids.

26. So what just happened?
Every turn of the Calvin cycle adds one more carbon into the cycle. So, every three turns makes a new 3- carbon PGAL molecule. This means that 6 turns through the cycle would give you enough carbon to make a glucose molecule!
For every PGAL molecule made, it takes 9 molecules of ATP and 6 NADPH.
The PGAL molecules can be used to make whatever organic compounds the plant needs to produce.

27. Review of Photosynthesis
includes
Light
dependent
reactions
Light
independent
reactions
occurs in
uses
uses
occur in
Light
Energy
Thylakoid
membranes
Stroma
ATP
NADPH
to produce of
to produce
ATP
NADPH O2
Chloroplasts
Glucose

28. The primary function of the light reactions of photosynthesis is
To produce energy-rich glucose from carbon dioxide and water
To produce ATP and NADPH
To convert light energy to the chemical energy of PGAL
To use ATP to make glucose

29. How well did you do today?
During photosynthesis, A) there is no ATP production B) ATP production occurs during the light-dependent reactions C) ATP production occurs during the dark reactions D) ATP production is replaced by NADPH production.

30. How well did you do today?
Where does the Calvin cycle of photosynthesis take place?
Stroma of the chloroplast
Thylakoid membrane
Cytoplasm surrounding the chloroplast
Outer membrane of the chloroplast