1. Energy Transfers
Cells Unit Targets 17-20

2. Cells Unit Objectives 17-20
C17 I can write out the correct reactants and products in the photosynthesis and the respiration reactions. C18 I can describe the steps in the light and dark reactions of photosynthesis in terms of inputs and outputs. C19 I can describe the steps in anaerobic respiration in terms of inputs and outputs. C20 I can describe the steps in aerobic respiration in terms of inputs and outputs.

3. Introduction: Where do we get all of our energy on Earth?
Directly or indirectly, almost all organisms get the energy needed for metabolism from the sun.

4. The Path:
Primary Consumers
Sunlight
Producers
Secondary Consumers

5. Target C17 – Photosynthesis portion
I can write out the correct reactants and products in the photosynthesis and respiration reactions.

6. What is photosynthesis?
A chemical reaction that changes light energy (sunlight) into chemical energy in the form of glucose (sugar).
We consider glucose stored energy because that is the molecule our bodies break down in order to get usable energy.

7. Photosynthesis Reaction:

8. Light is a Main Ingredient
White light is a combination of all colors in the visible light spectrum.
Visible light ranges from wavlengths ~400 nm (violet) to ~700 nm (red) on the electromagnetic spectrum.
ROY G BIV

9. How do we see color?
Pigments absorb certain wavelengths of light and reflect all others.
Look at the red heart.
What colors are being absorbed? Reflected?
Orange, Yellow, Green, Blue,
Indigo, and Violet are
absorbed; Red is reflected.

10. Where does it take place?
All plants, some protozoans (algae), some bacteria (cyanobacteria).
Most of the photosynthesis that takes place on Earth happens in the __________________
oceans (algae).

11. Why is it important?
To autotrophs, or producers, it’s how they get their food and meet their energy requirements.
To heterotrophs, or consumers, we meet our energy requirements by eating autotrophs directly (herbivores) or by eating another heterotroph (carnivores).

12. How Does it Work?
There are two parts, the light reactions and the dark reactions. Both take place in the chloroplasts.

13. Target C18
I can describe the steps in the light and dark reactions of photosynthesis.

14. Light Reactions Has to happen in the light!!!
Light energy is absorbed by pigments in the chloroplast:
Chlorophyll a and b
Absorb mostly red and blue light
Reflect green and yellow
Carotenoids
Absorb blue-green to green
Reflect red, yellow, orange

15. H2O splits, forming O2 gas and H+ ions
H+ ions are used to make ATP and NADPH, which are high energy molecules that will be used in the dark reactions.

16. Dark (Light –Independent ) Reactions
Can occur with or without light
ATP and NADPH made in the light reaction are used to change CO2 into C6H12O6 (glucose/sugar)

17. The Process In General Light Glucose O2 CO2 Calvin Cycle Light Phase
ATP
Light
Excites
Electrons
H2O Splits O2
Hits Chloroplast
NADPH
Dark Phase
Calvin Cycle
Glucose
CO2

18. Target C19 – Cellular Respiration portion
I can describe the steps in aerobic respiration in terms of inputs and outputs.

19. What is it?
A chemical reaction carried out by ALL living things (including plants) that changes chemical energy into usable energy (ATP).

20. Formula 6 O2 + C6H12O6 6 H2O + 6 CO2 + ATP OR
Oxygen + Glucose  Water + Carbon Dioxide + ATP

21. Why is it important?
Respiration supplies the energy (ATP) living things need to carry out all the processes of life!

22. How Does it Work? There are two stages: A) Glycolysis
B) Aerobic Respiration or Anaerobic Respiration

23. Step One - Glycolysis Takes place in the cytoplasm
C6H12O6 (glucose) is broken down into two 3-Carbon molecules called pyruvate.
This requires/uses 2 ATP, but it also makes/creates 4 ATP
This means there is a net gain of 2 ATP

24. After Glycolysis…
…if O2 is present, then aerobic respiration occurs. …if O2 is absent, then anaerobic respiration occurs.

25. If O2 is present… …then aerobic respiration occurs.
Aerobic respiration has two parts:
1.) The Kreb’s Cycle
2.) The Electron Transport Chain

26. The Kreb’s Cycle aka the Citric Acid Cycle
Takes place in the mitochondria
Pyruvate molecules made during glycolysis are used to make 2 ATP, CO2, and NADPH.

27. The Electron Transport Chain
NADPH made during the Kreb’s Cycle go into the Electron Transport Chain (ETC)
It occurs in the inner membranes of the mitochondria.
O2 combines with H+ ions, forming water and up to 34 ATP.

28. Total ATP made during aerobic respiration
Up to 38 ATP!!!

29. All of Cellular Respiration
Glucose
Glycolysis
2 ATP
(Net) O2 No O2
Krebs
Cycle
2 ATP
Fermentation
4 ATP
34 ATP
Lactic
Acid
Ethanol
ETC

30. Target C20 – Cellular Respiration portion
I can describe the steps in anaerobic respiration in terms of inputs and outputs.

31. If O2 is NOT present…
…then anaerobic respiration will occur after glycolysis.
Another name for anaerobic respiration is fermentation.
Fermentation is much less efficient than aerobic respiration.
There are two types of fermentation:
Lactic Acid
Alcoholic

32. Lactic Acid Fermentation
Pyruvate molecules that were made in glycolysis are converted into lactate (another word for lactic acid).
Lactate buildup in muscles causes soreness.
Pyruvate
Glucose
Lactic
Acid

33. Alcoholic Fermentation
Occurs in certain bacteria and fungi.
Pyruvate molecules made during glycolysis are converted to CO2 and ethanol (alcohol).
Ex. Yeast (a fungus) used in making bread, wine, and beer.
Pyruvate
Glucose
Ethyl
Alcohol
CO2

34. Either way…
…if fermentation (anaerobic respiration) occurs, then 4 ATP are produced!!!!