1. Chap 8- Photosynthesis Energy- the ability to do work
All living organisms must obtain and use energy to survive
Autotrophs: obtain energy from nonliving sources
Plants and some other types of organisms able to use light energy from the sun to produce food

2. Chap 8- Photosynthesis
Heterotrophs- must obtain energy from an outside source (cannot make own)
All organisms must release energy stored chemically by autotrophs
Energy stored in bonds formed between atoms
When bonds are broken (or new ones formed), energy released

3. Chap 8- Photosynthesis
Adenosine Triphosphate (ATP)- source of energy for the cell
To store energy:
Adds a phosphate onto ADP (diphosphate)
Forms ATP
To release energy:
Breaks high-energy bond to form ADP

6. Chap 8- Photosynthesis Not a good long-term storage molecule
Only keep a small amount in the cell
Single molecule of glucose stores 90x the energy found in ATP
Cell regenerates ATP from ADP as needed
Uses energy stored in food to do this

7. Chap 8- Photosynthesis
In the presence of light, plants transform carbon dioxide and water into carbohydrates
Release oxygen in the process
General equation:
6CO2 + 6H2O  C6H12O6 + 6O2
Carbon dioxide + water light sugars + oxygen

8. Chap 8- Photosynthesis
Plant cells contain light-absorbing chemicals, called pigments, that absorb certain wavelengths of visible light
Principle pigment is chlorophyll (a & b)
Absorb light in the blue/violet and red/orange wavelengths
Accessory pigments absorb additional wavelengths and pass onto chlorophyll

10. Chap 8- Photosynthesis
Light-absorbing pigments found in closed sacs called thylakoids
Pigments are embedded in the thylakoid membrane
Also embedded: proteins and enzymes necessary for photosynthesis
Proteins, pigments, and enzymes together make up photosystems

11. STROMA
GRANA

12. Chap 8- Photosynthesis
Process of photosynthesis involves three energy conversions:
Absorption of light energy
Conversion of light energy into chemical energy
Storage of chemical energy in the form of sugars

13. Chap 8- Photosynthesis
Light-dependant reactions: pigment molecules absorb light energy and convert it to ATP (light energy  chemical energy)
-Takes place on thylakoid membrane
Chemical energy (ATP) used to make 6-carbon sugars from CO2 – reaction known as the Calvin cycle
-Takes place in stroma (space surrounding thylakoids inside chloroplasts)

15. Chap 8- Photosynthesis Electron Carriers
When sunlight excites electrons in chlorophyll, electrons gain great amount of energy
High-energy electrons require special carrier molecules
These molecules transfer electrons (and their energy) to another molecule

16. Chap 8- Photosynthesis Process called electron transport
Group of carriers known as the electron transport chain
NADP+ : primary carrier molecule
Accepts 2 high-energy electrons and a H+ ion to form NADPH
One way of converting light energy into chemical energy

17. Chap 8- Photosynthesis Light-Dependant Reactions
Use energy from sunlight to produce energy carriers ATP and NADPH (from ADP and NADP+)
Oxygen gas is a by-product of these reactions (created by breaking water)
Two reaction centers:
Photosystem I
Photosystem II

18. Chap 8- Photosynthesis
Electrons passed along series of proteins/enzymes called electron transport chain; taken at end by NADP+  NADPH
Hydrogen ions pumped outside membrane; conc. gradient used to produce ATP
ATP synthase: enzyme in chain that produces ATP from ADP

20. Chap 8- Photosynthesis The Calvin Cycle Light-independent reactions
Plants use energy in ATP and NADPH to form long-term energy storage molecules
ATP & NADPH  high-energy sugars

21. Chap 8- Photosynthesis 1. 6 CO2 molecules enter cycle
Combine with 6 5-carbon molecules
Result = 12 3-carbon molecules
carbon molecules converted into higher-energy forms
Energy for conversion comes from ATP & NADPH

22. Chap 8- Photosynthesis
3. Two of the twelve 3-carbon molecule are removed from cycle
Used to make sugars and other molecules
4. Remaining ten 3-carbon molecules converted back into six 5-carbon molecules to start cycle again
Sugars used as building blocks & for energy by plants

23. Chap 8- Photosynthesis
Rate (activity per unit of time) of photosynthesis affected by:
Concentrations of O2 and CO2
Temperature
Light intensity
Availability of Water

24. Chapter 8 Review Ques. Pg. 217: B- plants A- sugars and O2 B- ATP
B- van Helmont
D- H2O & CO2
C- Reflects green
A- sugars and O2
D- chloroplasts
A- light absorption
B- NADPH
A- Calvin cycle

25. Chapter 8 Review Ques. Pg. 219: A- chlorophyll D- yellow-green
B- sugars A
C- green
E- absorption of light energy
C- oxygen
D- yellow-green
B- contain several pigments
D- chloroplasts

26. Chap 9- Cellular Respiration
Chemical Energy & Food
1g of glucose = 3811 calories of heat energy
Food energy not released all at once:
released gradually
Process begins with chemical pathway called glycolysis (small amount of energy)
If oxygen present: leads to one pathway
If no oxygen present: leads to different pathway

27. Chap 9- Cellular Respiration
Overview of Cellular Respiration
When oxygen is present:
-glycolysis 
-Krebs cycle 
-electron transport chain
Three pathways make up process called cellular respiration

28. Chap 9- Cellular Respiration
Releases energy from glucose and other food molecules in the presence of oxygen
General equation:
C6H12O6 + 6O2  6CO2 + 6H2O + E
glucose + oxygen  carbon dioxide + water + energy
Cell releases energy in little bits
Captures the energy in ATP

30. Chap 9- Cellular Respiration
Glycolysis
Process which breaks a molecule of glucose in half
Produces two molecules of pyruvic acid
Cell uses 2 ATP to produce 4 ATP
2 NADH (electron carrier molecule) produced from NAD+

32. Chap 9- Cellular Respiration
Fermentation
Anaerobic process (occurs without oxygen)
Two types:
Alcoholic fermentation- yeast cells and some bacteria
Pyruvic acid + NADH  alcohol + CO2 + NAD+

33. Alcoholic Fermentation

34. Chap 9- Cellular Respiration
Lactic acid fermentation- in muscles during heavy exercise; unicellular organisms
Pyruvic acid + NADH  lactic acid + NAD+
Microorganisms used to make variety of food products

35. Lactic Acid Fermentation

36. Chap 9- Cellular Respiration
Aerobic pathways: Krebs cycle and electron transport chain
MUST have oxygen to occur
Oxygen acts as the final electron acceptor in process

37. Chap 9- Cellular Respiration
Krebs Cycle
Pyruvic acid broken down into carbon dioxide in series of energy-extracting steps
1. Begins when pyruvic acid enters the mitochondrion
One carbon atom from pyruvic acid becomes CO2
Other two form acetyl-CoA (acetyl = 2 carbon atoms)

38. Chap 9- Cellular Respiration
Acetyl group added to a 4-carbon molecule to form citric acid (6-carbon molecule)
2. Cycle continues…
Citric acid broken down into a 4-carbon molecule (cycle starts again)
In process:
2 CO2 molecules released 4 NADH produced
1 ATP produced 1FADH2 produced
!!**per molecule of pyruvic acid**!!

41. Chap 9- Cellular Respiration
Tally so far…
Glycolysis:
2 ATP 2 NADH
Krebs Cycle:
2 ATP 8 NADH 2 FADH2
Total:
4 ATP 10 NADH 2 FADH2

42. Chap 9- Cellular Respiration
Electron Transport
ETC (electron transport chain) uses the high-energy electrons from the Krebs cycle to convert ADP into ATP
1. ETC located on inner mitochondrion membrane
Electrons passed along series of proteins
Oxygen accepts electrons (and two H+) and forms H2O at end of chain

43. Chap 9- Cellular Respiration
2. With every two electrons, H+ ions are pumped across membrane
Builds up concentration gradient across membrane
3. ATP synthase allows H+ ions across membrane
Uses energy of gradient to convert ADP to ATP (3 ATP for each pair of H+ ions)

45. Chap 9- Cellular Respiration
Final Tally
Glycolysis:
2 ATP 2 NADH
Krebs Cycle:
2 ATP 8 NADH 2 FADH2
ETC:
32 ATP (from NADH & FADH2)
Total:
36 ATP from one molecule of glucose

47. Chap 9- Cellular Respiration
38% efficiency of extracting energy from glucose
Gas engine-
6%-8% efficiency
Rest is lost as heat energy

48. Chap 9- Cellular Respiration
Comparison of Photosynthesis & Cellular Respiration
Photosynthesis “deposits” energy
Cellular respiration “withdraws” energy
Photosynthesis removes carbon dioxide from atmosphere, adds oxygen
Cellular respiration removes oxygen from atmosphere, adds carbon dioxide

49. Chap 9- Cellular Respiration
General equation for Photosynthesis:
6CO2 + 6H2O  C6H12O6 + 6O2
General equation for Cellular Respiration:
C6H12O6 + 6O2  6CO2 + 6H2O

50. Chapter 9 Review Ques.
Pg. 2:

51. Chapter 9 Review Ques.
Pg. 2: