Photosynthesis/ Cellular Respiration

1. Photosynthesis/ Cellular Respiration Chapter 8 and 9

2. ATP • ATP is the chief energy-storing molecule used by organisms. • Function • Provide cells with energy • Only form of energy the cell can use • Structure • Adenosine – Adenine and ribose • 3 phosphates • High energy bonds – when bonds are broken, energy is released

3. ATP Model • ATP Model High energy bond Ribose PO4 PO4 PO4 Adenine

4. Methods of Obtaining Food • Autotroph – organism that can make food from CO2 and an energy source such as sunlight • Ex: plants, algae, and bacteria • Main food made by autotrophs is glucose (C6H12O6) • Autotrophs are called producers • Heterotrophs – organisms that cannot make their own food • Referred to as consumers

5. Photosynthesis • Photosynthesis – the sun is the original source of energy on earth • Only plant cells can convert light energy into chemical energy • The process by which autotrophs convert sunlight to usable energy is call photosynthesis

6. Energy Conversion • Pigment – a molecule that absorbs certain wavelengths of light and reflects others • Photosynthesis pigment = chlorophyll • Chlorophyll reflects green light and absorbs all other wavelengths. • Chlorophyll converts the light energy it absorbs to the chemical energy of ATP

7. ChloroplastPg 208 • Organelle responsible for photosynthesis

8. Photosynthesis Equation Light • 6 H2O + 6CO2  6O2 +C6H12O6

9. Overview of Photosynthesis Location / Organelle: Reactants: Products: Energy Conversion:

10. Cellular Respiration • Process by which molecules are broken down to release energy in the form of ATP

11. Overview of Cellular Respiration • Aerobic respiration • Requires O2 • Produces 36 ATP molecules • Equation • C6H12O6 + 6O2  6CO2 +6H2O +36ATP • Anaerobic respiration • Does not use O2 • Produces 2 ATP • Also called fermentation • Alcoholic fermentation – produces alcohol • Lactic acid fermentation • Muscles do not contract as easily

12. Stages of Cellular Respiration • Glycolysis • Krebs cycle • Electron transport chain

13. Glycolysis • Process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid, a 3-carbon compound • Total energy yield = 4 ATP • Net ATP gain = 2 ATP • Advantages • Reaction is so fast that cells can produce thousands of ATP molecules in a few milliseconds • Does not require O2 (anaerobic) • In presence of O2, molecules enter Krebs Cycle and ETC releasing additional ATP, however, in the absence of O2, glycolysis is followed by fermentation with no additional energy production

14. Glycolysis Overview

15. Krebs Cycle • In the presence of oxygen, pyruvic acid is broken down into CO2

16. Electron Transport Chain • Products from Krebs cycle enter the ETC where high-energy electrons convert ADP to ATP

17. Mitochondria • Cellular respiration occurs in the mitochondria of all organisms • Structure of mitochondria • Matrix = liquid portion • Cristae – inner membrane where majority of ATP is produced

18. Energy and Exercise • Quick energy – body uses limited supply of ATP produced during glycolysis which last a few seconds • For the next 90 seconds the body produces ATP by lactic acid fermentation • Oxygen debt – caused when there is a shortage of oxygen due to lactic acid being produced as a byproduct. When exercise is finished the body must repay the debt with heavy breathing

19. Energy and Exercise • Long-term energy – cellular respiration produces ATP for exercise over 90 seconds • Cellular respiration is slower than fermentation. • Human bodies begin breaking down glycogen for the first 15-20 minutes of exercise • After that, human bodies begin breaking down fats and other molecules for energy

20. Respiration Overview • Location / Organelle: • Reactants: • Products: • Energy Conversion:

21. Photosynthesis vs. Cellular Respiration