1. Energy for Life Process Autotrophs- an organism that uses energy to synthesize organic molecules from inorganic substances Can make its own food Includes-plants, some bacteria, and algae Heterotrophs – must obtain energy from source other than self Includes animals, humans, some plants

2. Photosynthesis Capturing the energy in light

3. Overview of Photosynthesis Process by which sun’s energy is converted into chemical energy in the form of carbohydrates It occurs in the Plasma membranes of some bacteria Cells of algae Leaves of plants

4. Fig. 6.1 Journey into a leaf

6. Three stages of Photosynthesis 1. Capturing energy from sunlight. Produces oxygen. 2. Light energy converted to chemical energy. Using energy to make ATP and NADPH 3. Uses chemical energy to form organic compounds. ATP and NADPH are used to power the synthesis of carbohydrates from CO 2 Light-dependent reactions Light-independent reactions The Calvin cycle 6 CO 2 carbon dioxide + 12 H 2 O water + Light energy C 6 H 12 O 6 glucose + 6 O 2 oxygen

7. The Chloroplast – Where all 3 stages take place

9. Light absorption in Chloroplasts Each chloroplast is made up of different pigments Pigment-a compound that absorbs light Some pigments absorb certain colors more strongly than others

10. Colors of Visible Light

11. Chloroplast Pigments Chlorophyll a Only chlorophyll a is directly involved in light reaction of photosynthesis Chlorophyll b helps to capture light energy accessory pigment Carotenoids accessory pigment

12. Carotenoids Accessory pigments – help organism capture more energy Produce – yellow, orange, red, brown colors Mostly seen in flowers and fruits Also seen during fall when chlorophyll breaks down

13. Absorption Spectrum of pigments

14. Factors affecting photosynthesis 1. Light intensity 2. Amount of available Carbon Dioxide 3. Temperature (enzymes operate better in favorable temperatures)

15. Why is Photosynthesis important biologically? So……..

16. Cellular Respiration

17. Overview of Cellular Respiration Process in which organisms make ATP (energy) by breaking down organic compounds (carbohydrates) The overall process may be summarized as 6 CO 2 carbon dioxide (heat or ATP) + energy C 6 H 12 O 6 glucose + 6 O 2 oxygen + 6 H 2 O water Cellular respiration is carried out in two stages: –1. Glycolysis –2. Oxidation Occurs in the cytoplasm Occurs in the mitochondria

18. What is ATP? Adenosine triphosphate (ATP) is the major source of energy for cells formed when phosphate group and adenosine diphosphate (ADP) molecule bond Present in all living cells ATP is formed when protons move from inside the thylakoid to the stroma

19. Conditions for Cellular Respiration Oxygen present – Aerobic respiration Majority of ATP occurs in this process Oxygen absent – Anaerobic respiration No ATP created Lactic acid fermentation Alcohol fermentation

20. Harvesting Chemical Energy Organic Compounds Glycolysis Fermentation Aerobic Respiration ATP

21. Glycolysis: Breakdown of Glucose Produces 2 ATP Takes place in the cytosol (cytoplasm) Process takes a molecule of glucose and converts it into two molecules of pyruvic acid All organisms undergo glycolysis Presence/Absence of oxygen drives next set of reactions

22. Harvesting Chemical Energy Organic Compounds Glycolysis Fermentation Aerobic Respiration ATP

23. Fermentation No oxygen present – anaerobic pathway Occurs in the cytosol (cytoplasm) No ATP is created Regenerates an electron carrier molecule that keeps glycolysis going = keeps ATP in production

24. Harvesting Chemical Energy Organic Compounds Glycolysis Fermentation Aerobic Respiration ATP Without Oxygen

25. Lactic Acid Fermentation Important in manufacturing yogurt and cheese Occurs in your muscle cells during strenuous exercise. When oxygen is depleted at faster rate than can be supplied to cells, cells switch from aerobic to anaerobic respiration Lactic acid accumulates in muscle cells (in cytosol) Increased acidity in cytosol reduces cells capacity to contract = fatigue, pains, muscle cramps

26. Alcoholic Fermentation Example - Yeast Converts pyruvic acid into ethyl alcohol Important to wine and beer industry Yeast added to fermentation mixture Ethyl alcohol accumulates until it reaches a concentration that inhibits fermentation CO 2 released in production of wine CO 2 retained in production of champagne

27. Fermentation products & the organisms that ferment them Yogurt/bacteria Bread/fungus Soy sauce/fungus

28. Aerobic Respiration Oxygen present Occurs in cytosol in prokaryotes Occurs in mitochondria in eukaryotes Krebs Cycle and Electron Transport Chain Produces up to 38 ATP molecules Our bodies use ATP at a rate of one million molecules per cell per second

29. Harvesting Chemical Energy Organic Compounds Glycolysis Fermentation Aerobic Respiration ATP With Oxygen

30. Energy Requirements Present day unicellular organisms can acquire enough energy from anaerobic pathways Large multicellular organisms must acquire energy from aerobic pathways.

31. Do plants carry out cellular respiration? Yes! Cellular respiration does not mean breathing – it is breaking down organic compounds to release stored energy.

32. Equation for Cellular Respiration C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + ATP Reactants = Glucose (sugar), Oxygen Products = Carbon dioxide, Water, Energy