1. Photosynthesis and Respiration
Chapter 5

2. Key Terms
Photosynthesis- the process where plants convert light energy (sun) into chemical energy (glucose, starch)
Respiration- the process where chemical energy (glucose) is broken down into ATP (adenosine triphosphate)
Autotroph- organisms that can make their own organic compounds
Heterotroph- organisms that must eat other organic compounds

3. Transfer of energy to ATP
This is similar to burning gasoline to get the energy from it.
Our mitochondria will “burn” sugar and turn it into ATP. Our cells will then use the ATP to do work.
ATP is a nucleotide that has the ability to store energy in its bonds
ATP will be broken down into ADP + P and then recycled back into ATP when we eat.

4. PHOTOSYNTHESIS Happens in three stages-
1. energy is captured from the sun
2. Light energy is converted into ATP and NADPH
3. ATP, NADPH, and CO2 are used to make organic compounds such as glucose, sucrose and starch

5. Photosynthesis

6. Overall Equation
6CO2 + 6H2O + light  C6H12O6 + 6O2

7. Stage 1 Light Absorption
Light is found as wavelengths of electromagnetic spectrum- ROYGBV
Pigments- light-absorbing substances
Chlorphyll- absorbs all but green
Carotenoids- absorb all but orange
The colors we see are the wavelengths that are being reflected by a pigment

8. Light absorption

9. Oxygen production
Sunlight is absorbed by thylakoids- disk-shaped structures that contain chlorophyll
This energy “excites” electrons which cause the breakdown of water molecules
Water is split into 3 parts
2 H+ ions
Oxygen molecules
2 electrons
The electrons replace those lost by energy absorption
Oxygen is waste
The 2 H+ ions will be used later

10. Electron Transport Chain I
The electrons that have been freed from H2O are absorbed by molecules called PHOTOSYSTEM II
They accumulate and leave and are absorbed by an ELECTRON ACCEPTOR
They travel through an ELECTRON TRANSPORT CHAIN where they slowly release energy to ATP synthase
ATP synthase uses the energy to produce ATP

11. ELECTRON TRANSPORT CHAIN II
The “spent” electrons arrive at PHOTOSYSTEM I and are “excited” again by light energy
The electron accumulate again and are accepted by a second ELECTRON ACCEPTOR
The electron travel down a second ELECTRON TRANSPORT CHAIN where they provide the energy to join NADP+ and the 2H+ ions that were released earlier

13. SO FAR At this point we have USED We have also MADE
Light energy
H2O
We have also MADE
Oxygen as waste
Since this part of photosynthesis must have light in order to work it is called LIGHT DEPENDENT PHASE

14. CALVIN CYCLE Also called the “LIGHT-INDEPENDENT” phase
“carbon-dioxide” fixation- transferring CO2 into organic compounds.
ATP and NADPH that were made earlier will be used during this phase

15. Calvin Cycle steps 3 CO2 join with RuBP (ribulose biphosphate)
This forms 3 6-Carbon molecules that immediately split to form 6 3-carbon molecules called PGA
PGA uses the energy from 6 ATP and 6 NADPH to be converted into 6 PGAL
5 PGA use 3 ATP and are converted back to RuBP. The 1 remaining PGAL is used to make organic compounds
Since only 3 of the 6 CO2 are used, the Calvin Cycle must go through twice
The result is a 6 carbon organic molecule - glucose

17. Factors that affect photosynthesis
There reaches a point where so much sunlight is absorbed that photosynthesis cannot happen any faster. Think of a car that reaches it’s top speed.
Water loss happens too fast

18. Cellular Respiration Key Terms Aerobic- with oxygen present
Anaerobic- without oxygen present
Glycolysis- splitting of sugar
NADH-
FADH2
Kreb’s Cycle-
Fermentation

19. Aerobic Respiration

20. Stages of Respiration
Glycolysis- splitting of sugar that happens in the cytoplasm
Aerobic Respiration-
Kreb’s Cycle
Electron Transport Chain
Anaerobic Respiration
Either Alcoholic Fermentation or Lactic Acid Fermentation

21. Glycolysis Occurs in cytoplasm
1 glucose is split into 2 Pyruvate molecules
This uses 2 ATP but produces 4 ATP and 2 NADH
The net gain from glycolysis is 2 ATP

23. KREB’S CYCLE
If O2 is present then the pyruvate will enter the mitochondria and proceed through a series of events
This immediately makes 1 NADH molecule and pyruvate is converted into Acetyl Co-enzyme A (ACoA)
At the end of the cycle three molecules are made for every ACoA
1 ATP
3 NADH
1 FADH2
Since 2 pyruvate are made during glycolysis Kreb’s Cycle must happen twice.

25. Electron Transport Chain
NADH and FADH2 will lose electrons and H+ ions and will be converted into ATP
This is similar to ATP production in photosynthesis
For every NADH= 3 ATP
For every FADH2= 1 ATP

26. ATP Production 2 NADH from glycolysis = 6 ATP 2NADH from ACoA = 6 ATP
6 NADH from Kreb’s cycle= 18 ATP
2 FADH2 from Kreb’s cycle= 4 ATP
2 ATP from Kreb’s cycle
Electron Transport will yield up to 34 ATP + 2 ATP from Kreb’s + 2 ATP from Glycolysis = 38 ATP

27. ATP PRODUCTION

28. Anaerobic respiration
Still begins with glycolysis
If oxygen is ABSENT then the pyruvate made will not enter Kreb’s cycle to recycle NAD+
Instead the pyruvate enters one of two fermentation processes
Lactic acid fermentation
Alcoholic fermentation

29. Lactic acid fermentation
Pyruvate will be converted into an ion of LACTIC ACID
If muscles operate without oxygen then lactic acid will build up in the muscles causing soreness

30. Alcoholic fermentation
Pyruvate may enter alcoholic fermentation in other organisms
Pyruvate will be converted into alcohol and CO2
Organisms such as bacteria and fungi such as yeasts perform this type of fermentation.
We use these actions to produce wine, beer, sourdough, breads, and ethanol
In both types of fermantation- no further ATP is made after glycolysis

31. Efficiency of ATP production
The total amount of ATP made from glycolysis is 2
Both types of fermentation will yield no further ATP
Aerobic respiration will yield up to another 36 ATP
Aerobic respiration is obviously the more efficient process

32. What does all this mean?
The food that we eat is broken down (digested) into simple molecules- carbohydrates, lipids, proteins.
These are absorbed by our cells and respiration starts. So all that food we eat will be used to recharge ADP + P into ATP
ATP is the rechargable batteries that our cell use to do work. When the batteries run low we eat to do respiration to recharge them.
If we do not use all the energy then it will be stored in cells called fat cells.