1. Maintaining Dynamic Equilibrium
Photosynthesis
and Respiration

2. The Journey of a Carbon Atom
Hi…I’m a Carbon Atom and I will be your guide through this unit on photosynthesis and respiration.
You will see that these two processes have a lot to do with each other.

3. Chemical Equations Photosynthesis CO2 + H2O + Sunlight C6H12O6 + O2
What do you notice about their two chemical equations?
Photosynthesis
CO2 + H2O + Sunlight C6H12O6 + O2
Respiration
C6H12O6 + O CO2 + H2O + Energy
Enzymes
Enzymes

4. My Story…
As you know, carbon molecules like me are found in many different places. We are found in inorganic compounds like CO2
When I am with my friend the Hydrogen atom in a compound, it is known as organic. For example when we appear together in glucose C6H12O6.

5. One day I was happily floating around in the air as part of a carbon dioxide molecule when I was sucked up into the leaf of a blueberry bush!
This was a little bit of a disappointment because I was enjoying floating around on the breeze on a nice summer day!

6. The Leaf…
is where I entered the plant. The stoma on the bottom side of the leaf are tiny holes. They open and close with the help of guard cells to exchange gases and water with the outside environment.
Conveniently, the leaf is the part of the plant where photosynthesis takes place.

7. Into the Chloroplast!
When I was sucked into the chloroplast I knew I wouldn’t be part of carbon dioxide for long!

8. Light Reactions
You see, photosynthesis takes place in a specialized organelle found in plant cells called the chloroplast.
The first phase takes place in the grana, where the pigment chlorophyll is stored. The sunlight shines on the chlorophyll and this splits molecules of water right in half!
Grana

9. Dark Reactions
The hydrogen atoms from the water are carried out of the grana into the stoma where I am waiting with my oxygen friends.
Stroma

10. Sugar!!
Hydrogen is attached to me and my friend oxygen and you know what that means… sugar!
Voila…I have gone from inorganic CO2 to an organic carbohydrate!
Glucose – C6H12O6
That’s photosynthesis…let’s recap…

11. Photosynthesis Equation
__CO2 + __H2O + Sunlight C6H12O6 + __O2
The blueberry bush will use dehydration synthesis to attach me to many other glucose molecules for storage. Do you know what this polysaccharide is called??
enzymes

12. I won’t stay for long STARCH
So here I sit, now I am part of a starch molecule that is stored in the blueberry on this bush…
This sounds lovely…BUT there is a deer sniffing at the bush and it looks like he just might take a bite!
I’m in that berry…

13. Well here I go…
Turns out that deer was hungry and I am on the move again!
He took a large bite and all of a sudden I am in the deer’s mouth!

14. Digestion…
That deer chewed me up nice and good and now I am on the way down his esophagus and into the stomach.
You know since I am now part of a starch molecule I am going to be broken down by amylase into one molecule of glucose again. Just like the good old days back in the leaf!
When I am digested water is added to break the starch molecule into it’s building blocks. Do you remember the name of this process?

15. Hydrolysis
amylase
Starch + H2O Glucose

16. Transport…
Now that I am a single glucose molecule I can be absorbed into the blood stream of the deer.
I will be carried to a cell that needs energy…this is the life process we call transport.

17. TROUBLE!
This deer has come in contact with a hunter!! He must run to get away!

18. Into a muscle cell
The glucose molecule I am part of is sucked up into a muscle cell! Glucose will be used to help this deer run faster and escape the hunter!
The muscle cell will use the glucose molecule to create energy to keep up its hard work through the metabolic reaction called cellular respiration.

19. Cellular Respiration
These muscle cells need a lot of energy to keep the deer moving fast!
They are loaded with mitochondria, the organelle where cellular respiration takes place.

20. Respiration Equation C6H12O6 + __O2 __ CO2 + __H2O + 36 ATP enzymes
Energy for
cells to do work!!!
ATP is like a mousetrap!

21. Step one: Glycolysis
Once my glucose molecule enters the cytoplasm of the muscle cell, it is split apart during a process called glycolysis. This only makes 2 ATP molecules and makes me part of one of two pyruvic acid molecules.

22. Step two: Krebs Cycle
Now part of pyruvic acid I enter the mighty mitochondria where I will really supply some energy!
Together with oxygen the deer has been breathing in from the atmosphere we will make 34 more ATP molecules to keep his legs going!

23. CO2 Again!
Once the ATP molecules are made I become part of a waste product carbon dioxide!
I am together with oxygen once again as CO2! Amazing how fast I have come full circle!

24. Out into the atmosphere!
The deer has no use for carbon dioxide so the carbon dioxide molecule is carried by the blood to the lungs and whoosh! I am exhaled out into the summer breeze once again…just in time to see the deer escape the hunter!
I am glad I could help!

25. Busy Day!
So as you can see carbon atoms have a very important job and we are constantly changing form!

26. A Cycle… I started the day as a gas in the air (CO2)
I was sucked up into a leaf and during photosynthesis became part of glucose (C6H12O6)
A deer ate me and used me for energy to escape a hunter! During this process of cellular respiration I was converted back into CO2
This will all happen to me again before the day is through!

27. A Cycle… Oxygen and Glucose Energy OUT Energy IN ATP
Carbon Dioxide and Water