1. Photosynthesis and Respiration
Standard Set 1 – Cell Biology 1f, 1g

2. Life from the Sun Light is central to the life of plants.
Photosynthesis is the most important chemical process on Earth.
It provides food and oxygen for virtually all organisms.
Photosynthesis converts light energy into chemical energy and stores it in food.

3. The fuel for Respiration ultimately comes from Photosynthesis
All organisms have the ability to harvest energy from organic molecules.
Plants, but not animals, can also make these molecules from inorganic sources by the process of photosynthesis.
Aerobic respiration is the release of energy from food using oxygen.

4. Photosynthesis and Aerobic Respiration form a Cycle
C6H12O6 + 6O2
6CO2 + 6H2O
SUNLIGHT
The end products of photosynthesis are the reactants for aerobic respiration
The waste products of aerobic respiration are the reactants for photosynthesis

5. An Overview of Photosynthesis
Photosynthesis is the process by which some organisms use light energy to make sugar and oxygen gas from carbon dioxide and water.
Carbon dioxide
Water
Glucose
Oxygen gas
PHOTOSYNTHESIS

6. An Overview of Respiration
Respiration is the process which releases energy from glucose and distributes it to ATP molecules to be used by the cell.

7. PHOTOSYNTHESIS AND RESPIRATION Take Place In Specific Organelles
Photosynthesis takes place in the chloroplasts of plant cells.
Cellular Respiration takes place in the mitochondria of both plant and animal cells.

8. Linked Processes Aerobic Respiration Photosynthesis
Energy-releasing pathway
Requires oxygen
Releases carbon dioxide
Photosynthesis
Energy-storing pathway
Releases oxygen
Requires carbon dioxide
Ps provides a carbon source for all of life

9. A CLOSER LOOK AT PHOTOSYNTHESIS
LIGHT ENERGY
12H2O + 6CO2
6O2 + C2H12O6 + 6H2O
water
oxygen
glucose
water
carbon dioxide

10. Where do photosynthetic products come from?
Reactants:
Products:
The oxygen given off in photosynthesis does not come from the CO2 starting material. Instead it comes from water that is broken down to donate electrons.
Sugar (glucose) is made by the reduction of CO2

11. PLANTS PRODUCE O2 GAS
The O2 liberated by photosynthesis is a byproduct made by splitting water (H2O).
Water molecules are split apart and electrons and H+ ions are removed, leaving O2 gas.

12. Photosynthesis occurs wherever there are chloroplasts
LEAF CROSS SECTION
MESOPHYLL CELL
LEAF
Mesophyll
Stoma
(pl. stomata)
CHLOROPLAST
Intermembrane space
Outer
membrane
Granum
Inner membrane
Grana
Stroma
Thylakoid compartment
Stroma
Thylakoid

13. Photosynthesis occurs in two stages linked by ATP and NADPH
The complete process of photosynthesis consists of two linked sets of reactions:
The Light Reactions convert light energy to chemical energy and produce O2 in the thylakoids.
The Calvin Cycle assembles sugar molecules from CO2 using the energy-carrying products of the light reactions in the stroma.

14. LIGHT REACTIONS (in grana) CALVIN CYCLE (in stroma)
SUMMARY of PHOTOSYNTHESIS
H2O
CO2
Chloroplast
Light
NADP+
ADP + P
LIGHT REACTIONS (in grana)
CALVIN CYCLE (in stroma)
ATP
Electrons
NADPH O2
Sugar

15. CELLULAR RESPIRATION How Cells Obtain Energy To Sustain Life
The process which releases energy from glucose and distributes it to ATP molecules to be used by the cell
C6H12O6 + 6O2  6CO2 + 6H2O + ATP
Glucose + oxygen Carbon Dioxide Water Energy
All cells must break carbon bonds in glucose to release energy
Energy stored in bonds is called “chemical energy”

16. ATP PROVIDES ENOUGH ENERGY TO MAKE A REACTION GO
What is ATP?
Nucleotide
Adenosine Triphosphate P O
P =
P-P~P
Adenine
Ribose sugar (5 carbon sugar) O

17. Why ATP? Why not use glucose as a direct Energy source?
Glucose would provide far too much energy for one simple reaction!
Many steps
P-P~P
glucose
ATP O

18. ATP = full charged battery / ADP = empty battery

19. Respiration is more than breathing Why do we need oxygen
Respiration is more than breathing Why do we need oxygen? Answer: Oxygen is needed to release the energy from our food.

20. CELLULAR RESPIRATION
Cellular Respiration is the chemical breakdown of carbohydrates (glucose) into high energy ATP molecules and low energy end products (CO2 and H2O)

21. AEROBIC RESPIRATION OCCURS IN MITOCHONDRIA

22. Cellular Respiration can happen with or without Oxygen But the results are not the same …
Glucose is converted into two pyruvate molecules producing a small amount of ATP and NADH.
Fermentaion happens when oxygen is absent (anaerobic) and the pyruvate is converted into either lactic acid or ethyl alcohol in the cytoplasm.

23. Cellular Respiration can happen with or without Oxygen But the results are not the same …
When oxygen is present (aerobic), pyruvate and NADH are used to produce a large amount of ATP (36 total!) in the mitochondria.

24. Overview of Aerobic Respiration
C6H O2  6CO2 +6H20 + ENERGY (ATP)
3 major steps:
Glycolysis
Kreb’s cycle
Electron
Transport
Chain

25. Summary of Aerobic Respiration For each glucose molecule that enters cellular respiration, 36 ATP molecules are produced
Glycolysis
2 ATP
Krebs cycle
Electron transport
32 ATP