1. Photosynthesis and Cellular Respiration

2. Why do we eat?
Present this question to students and have them take 60 sec to write an answer on their paper. write student responses on the board
Possible responses:
Because we get hungry
Because we need food to live
Because we need energy
Because if we don’t, we’ll starve
Because we need nutrients
Leading questions:
What happens if we don’t eat?
Did you ever skip breakfast and lunch and then try to do gym? What happened?

3. Lunch (The Big Picture)
So where does the energy come from?
Food – where did the food get it from?
Plants – how so? I ate a steak, that’s not a plant.
The sun – how so? I can’t eat sun beams. Is there something that can?
So how does the plant get its energy?
photosynthesis

4. Energy Transformations
Energy- is the ability to do work (you love physics)
Thermodynamics- the study of how energy flows and changes in the universe
In order to talk about how we get energy, we need to first discuss what energy is and how it works.

5. Laws of Thermodynamics
1st Law of Thermodynamics- Energy can change form, but it can not be created or destroyed
When you eat- The chemical energy in your food changes to mechanical energy (movement)
2nd Law of Thermodynamics- Systems go from order to disorder (entropy)
When your body changes the energy from chemical to mechanical, some energy is lost as heat

6. Energy can come from the Sun
Heterotrophs -get their energy by eating food
Autotrophs -make their energy from the sun

7. Picture of a Metabolic Pathway
Metabolism
Picture of a Metabolic Pathway
Metabolism- all of the chemical reactions that take place inside cells
Metabolic pathway- a series of reactions where the product of one reaction is the reactant for the next
So now we know that energy comes from the sun because plants harness it and then when animals eat the plants, the animals pick up the plant’s energy.
so how do plants and animals “pick up” energy?
Energy is stored in chemical bonds. When bonds are made and broken, energy can be stored or used to do work.
This is metabolism

8. Two types of Metabolic Pathways
Catabolic- energy is released by breaking large molecules into small molecules
Anabolic- energy is used to build large molecules from small ones
Energy from catabolic pathways fuel anabolic pathways
Anabolic
Catabolic

9. Photosynthesis—light energy from the Sun is converted to chemical energy for use by the cell
Cellular respiration—organic molecules are broken down to release energy for use by the cell

10. ATP: The Unit of Cellular Energy
ATP – Cell Energy
Releases energy when the bond between the second and third phosphate groups is broken

11. Photosynthesis

12. Photosynthesis Two phases
Light dependent Reaction – Light energy absorbed and changed into chemical energy
Light independent Reaction – chemical energy changes into a stable form (glucose)

13. The Light Reaction
First light is absorbed by chloroplasts

14. Thylakoids Thylakoids contain light absorbing pigments
Pigments absorb light and reflect others
We see the reflected color

15. Electron Transport

16. Dark Reaction- Calvin Cycle
Calvin cycle - energy is stored in organic molecules such as glucose

17. Turn to page 16

18. Light Reaction
Dark Reaction

19. STOP

20. Cellular Respiration

21. Overview of Cellular Respiration
Organisms obtain energy in a process called cellular respiration.
The equation for cellular respiration is the opposite of the equation for photosynthesis.

22. Two Parts
Glycolysis
Aerobic Respiration

23. Glycolysis
Glucose is broken down in the cytoplasm
Takes place in ALL Cells
Bacteria
Protists
Plants
Animals
Fungi
Glucose converted into 2 pyruvate, 2 ATP and 2NADH are produced

24. Anaerobic- NO OXYGEN Two main types
Lactic acid fermentation
Alcohol fermentation
Anaerobic Respiration- takes place when there are no mitochondria (bacteria) or oxygen is not available
Downside  low ATP Payoff

26. Aerobic Respiration Krebs Cycle
Most of the energy is still in the pyruvate
The net yield from the Krebs cycle is
6 CO2
2 ATP (only useable energy)
8 NADH
2 FADH2.

27. Electron Transport Final step in the breakdown of glucose
~34 ATP produced
O2 is the Final electron acceptor = H2O

28. Overview of Cellular Respiration
Location
Main Activity
High Energy Molecules Made
Glycolysis
Krebs Cycle
ETC
Cytoplasm
-Glucose is converted into pyruvate
2 ATP
2 NADH
Mitochondria
matrix (fluid)
-Pyruvate converted to CO2 (continues cycle)
-provides H for transport chain (NADH/FADH)
8 NADH
2 FADH
Mitochondria cristae (membrane)
-protons from NADH/FADH  ATP
-Electrons and protons combine with oxygen to make water
~32-34 ATP