1. Photosynthesis & Cellular Respiration

2. Energy and Living Things
Where does energy in food come from?
Directly or indirectly, almost all energy comes from the sun

3. Metabolism
Metabolism involves either using energy to build molecules or break down molecules in which energy is stored.

4. Photosynthesis
Photosynthesis- light energy is changed into chemical energy (sun to sugar).

5. Autotrophs
Autotrophs  organisms that can use energy from the sun through photosynthesis
Examples: plants, algae, some protists and bacteria

6. Heterotrophs
Heterotrophs  organisms that get energy from food instead of directly from the sun
Examples: humans, animals, fungus, some protists and bacteria

7. Flow of Energy
****Use different organisms!!!!

8. Cellular Respiration
Cellular Respiration- METABOLIC PROCESS SIMILAR TO BURNING FUEL; RELEASE OF ATP (TAKES PLACE IN MITOCHONDRIA)

9. ATP- Adenosine Triphosphate
ATP is made up of:
1 adenine,
1 ribose, and
3 phosphates.
When the outer phosphate group detaches from ATP, energy is released.

10. ATP- Adenosine Triphosphate

11. Flow of Energy
When you eat a hamburger, you get energy from the sun (indirectly). The beef comes from a cow that ate grass. The bun, lettuce, and tomatoes all come from plants

12. Stages of Photosynthesis
Stage 1 (Absorption of Light Energy):
Energy is captured from sunlight.

13. Stages of Photosynthesis
Stage 2 (Conversion of Light Energy):
LIGHT ENERGY IS CONVERTED TO CHEMICAL ENERGY WHICH IS STORED IN ATP. THE ENERGY CARRIER MOLECULE IS NADPH.

14. Stages of Photosynthesis
Stage 3 (Storage of Energy):
Chemical energy stored in ATP and NADPH powers the formation of organic compounds using CO2.
***Stage 3 can happen in absence of sunlight IF stage 1 & 2 have occured

15. Equation for Photosynthesis
6 CO2 + 6 H2O C6H12O6 + 6 O2
Light
Glucose
(sugar)

16. Photosynthesis

17. Stage 1: Absorption of Light
Sunlight contains a mixture of all the wavelengths (colors) of visible light.
Pigments- contain light absorbing substances. The color an object is tells us what color is reflected by that object and is not absorbed.

18. Stage 1: Absorption of Light
Chlorophyll is the main pigment involved in photosynthesis. It absorbs blue and red and reflects green and yellow.
The reflection of green light makes many plants look green, especially leaves. The leaves are where most photosynthesis occurs.

19. Stage 1: Absorption of Light
2 types of chlorophyll:
chlorophyll a and chlorophyll b
Yellow pigments are carotenoids
(Carotenoids are responsible for fall colors in leaves and the color of fruits, vegetables, and flowers.)

20. Stage 1: Absorption of Light
Oxygen is produced in the 1st step of photosynthesis. Where does this happen?
Leaf Chloroplast Thylakoids

21. Draw a chloroplast with thylakoids labeled.

22. Stage 1: Absorption of Light
When light is absorbed by the thylakoids, energy is transferred to electrons in chlorophyll . The electrons get “excited” and jump from chlorophyll to other nearby molecules in the thylakoid membrane. The electrons are used to power the 2nd step of photosynthesis.

23. Stage 1: Absorption of Light
The excited electrons are replaced by electrons from water molecules.
The water molecules are split by an enzyme inside the thylakoid.
H+ electrons are taken by the chlorophyll, leaving oxygen.

24. Stage 2: Conversion of Light
An excited electron is passed along the membrane like a ball being passed down a line of people.
ETC (Electron Transport Chain)- a series of molecules through which excited electrons are passed along a thylakoid membrane

25. Stage 1 & 2 Summary: (Light Dependent)
Pigment molecules in the thylakoids of chloroplasts absorb light energy. Electrons in the pigments are excited by light and move through ETC’s in the thylakoid membranes.
Continued on next slide

26. Stage 1 & 2 Summary: (Light Dependent)
These electrons are replaced by electrons from H2O split by an enzyme. Oxygen atoms from H2O molecules combine to form oxygen gas (O2). Hydrogen ions accumulate inside setting up a concentration gradient that provides the energy to make ATP and NADPH.

27. Stage 3: Storage of Energy
Carbon atoms from carbon dioxide in the atmosphere are used to make organic compounds in which chemical energy is stored.

28. Stage 3: Storage of Energy
The transfer of carbon dioxide to organic compounds is called carbon dioxide fixation.

29. Stage 3: Storage of Energy
Calvin Cycle- a series of enzyme-assisted chemical reactions that produces a 3-carbon sugar.

30. Factors that affect Photosynthesis include:
1). Amount of light
2). Amount of CO2
3). Temperature
(certain temps
can inactivate
certain enzymes)

31. Cellular Respiration Equation C6H12O6 + 6O2 6CO2 + 6H2O + energy (ATP)
enzymes
C6H12O6 + 6O CO2 + 6H2O + energy
(ATP)

32. Cellular Respiration
Most Foods we eat contain USEABLE ENERGY. But before you can use that energy it is transferred to ATP

33. Cellular Respiration
Cellular Respiration- the process cells use to make energy; uses glucose and oxygen to make ATPs which are necessary to run our cells and body

34. Cellular Respiration
OXYGEN in the air you breathe make the production of ATP more EFFECIENT, although some is made without oxygen.

35. Cellular Respiration
Metabolic process that REQUIRES OXYGEN is called AEROBIC.
A metabolic process that DOES NOT REQUIRE OXYGEN is called ANAEROBIC meaning “without air”.

36. Stage One- Breakdown of Glucose
Primary fuel for cellular respiration is GLUCOSE
GLUCOSE is broken down in the CYTOPLASM during the process called GLYCOLYSIS.

37. Stage Two: Production of ATP
When OXYGEN is present, PYRUVATE produced during glycolysis enters a MITOCHONDRION and is converted to a two-carbon compound.
This reaction produces 1 carbon dioxide, 1 NADH molecule, and 1 two-carbon acetyl that is attached to a molecule called a COENZYME A (CoA) forming a compound called ACETYL CoA.

38. Electron Transport Chain
Acetyl-CoA enters a series of enzyme assisted reactions called the KREB’S CYCLE
Electron Transport Chain

39. Electron Transport Chain
In AEROBIC RESPIRATION electrons donated by NADH and FADH2 pass through an ELECTRON TRANSPORT CHAIN located in the INNER membranes of MITOCHONDRIA.

40. Section 9.3 Summary – pages 231-237
STEPS FOR ELECTRON TRANSPORT CHAIN
The electron transport chain pumps HYDROGEN ions out of the inner compartment.
Label on picture.
Section 9.3 Summary – pages

41. STEPS FOR ELECTRON TRANSPORT CHAIN
2. At the end of the chain ELECTRONS and HYDROGEN ions combine with OXYGEN forming WATER.
Label on picture.

42. STEPS FOR ELECTRON TRANSPORT CHAIN
3. ATP is produced as hydrogen ions diffuse into the inner compartment through a CHANNEL protein.
Label on picture.

43. Fermentation in the Absence of Oxygen
What happens when there is not enough oxygen for aerobic respiration?
Under ANAEROBIC conditions, electrons carried by NADH are transferred to PYRUVATE produced during GLYCOLYSIS. This recycles NAD+ needed to continue making ATP.

44. Fermentation in the Absence of Oxygen
The recycling of NAD+ using an ORGANIC HYDROGEN ACCEPTOR is called FERMENTAION.

45. Two Types of Fermentation
1). Lactic Acid Fermentation
A three-carbon PYRUVATE is converted to a three-carbon LACTATE.
Lactate is the ion of an organic acid called LACTIC ACID.

46. Examples of Lactic Acid fermentation
Used in the production of YOGURT and CHEESE; also during VIGOROUS exercise a build up of lactate causes muscle SORENESS.

47. Two Important Types of Fermentation
2). Alcoholic Fermentation
A three-carbon PYRUVATE is broken down into ETHANOL (ethyl alcohol).
CARBON DIOXIDE is released in the process.

48. Examples of alcoholic fermentaion
Used in the preparation of WINE, BEER, rising of BREAD dough, and CARBONATION of alcoholic beverages.

49. Although both processes use electron carriers and form ATP, they accomplish quite different tasks as shown in the table.
Table 9.1 Comparison of Photosynthesis and Cellular Respiration
Photosynthesis
Cellular Respiration
Food synthesized
Food broken down
Energy from sun stored in glucose
Energy of glucose released
Carbon dioxide taken in
Carbon dioxide given off
Oxygen given off
Oxygen taken in
Produces sugars from PGAL
Produces CO2 and H2O
Requires light
Does not require light
Occurs only in presence of chlorophyll
Occurs in all living cells
Chapter Assessment