1. Cell Energy ATP and Enzymes Respiration Photosynthesis

2. Energy Energy – the ability to do work ATP – molecule that stores energy in which organisms use; adenosine triphosphate Calorie – the unit used to measure the amount of energy food contains Metabolism – the collection of the chemical reactions that occur in a cell; anabolism and catabolism

3. Energy Potential energy – stored energy, energy that results from position –Food has potential, stored, energy Kinetic energy – energy of motion –Our bodies convert food into kinetic energy

4. ATP and ADP ADP – adenosine diphosphate turns into ATP through the process of phosphorylation, addition of a phosphate group to a molecule ADP + P ATP Energy from food Synthesis of ATP Energy used by cell Hydrolysis of ATP

5. Role of Enzymes Proteins that help chemical reactions in living organisms and help control the chemical environment at cell’s level Catalyst – a chemical that helps a chemical reaction, but is not consumed or changed in the reaction –Enzymes act as a catalyst in biochemical reactions

6. Role of Enzymes

7. Reactant – the reactant molecule in which the enzyme reacts Substrate – the area on the enzyme where the substrate fits in shape and chemistry Active site – where substrate fits Product – the molecule produced in the enzyme reaction Pepsin – an enzyme produced by the stomach for digestion of proteins Amylase – an enzyme produced in the salivary glands for the digestion of carbohydrates

8. Role of Enzymes Enzymes lower the activation energy required for chemical reactions to take place

9. Cellular Respiration The process by which living things release energy from food C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + ATP glucose + oxygen  carbon + water + energy dioxide

10. Cellular Respiration Redox reaction – a chemical reaction in which electrons are transferred between atoms Reduction – a chemical reaction that results in a gain of electrons –Glucose loses electrons and hydrogen Oxidation – a chemical reaction that results in a loss of electrons –Oxygen gains electrons and hydrogen C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + ATP

11. Cellular Respiration Electron carriers – special molecules that carry electrons from one set of reactions to another NADH (nicotinamide adenine dinucleotide) – the main electron carrier involved in cellular respiration

12. Stages of cellular respiration Glycolysis –Glucose is split Kreb’s Cycle –Produces ATP, NADH, and FADH 2 Electron Transport Chain –Produces ATP

13. Glycolysis Uses 2 ATP molecules to split glucose into two 3-carbon compounds. Bonds rearrange and produce NADH from NAD+, along with two 3-carbon compounds. Two 3-carbon compounds are converted into pyruvic acid, along with 4 ATP. In order to move into the mitochondria, pyruvic acid is converted into acetic acid, which bonds to coenzyme A to create acetyl CoA. It releases acetic acid into mitochondria

14. Glycolysis Glucose 3-carbon compound Pyruvic Acid 2 ATP NAD+ NADH NAD+ NADH 2 ATP

15. Kreb’s Cycle Acetic acid enters the matrix of mitochondria. The cycle also uses 3 NAD+ and 1 FAD molecule through a series of chemical reactions. The products are 2 CO 2, 1 ATP, 3 NADH, and FADH 2 molecules.

16. Kreb’s Cycle

17. Electron Transport Chain NADH transfers electrons to first electron carrier. High energy electrons passed down chain. Energy is released each time electrons are moved down the chain, which pumps H+ across the membrane. Water is also formed. The energy released, with ATP synthase, produces ATP by adding phosphate to ADP

19. Fermentation Anaerobic – not requiring oxygen Fermentation – process for making ATP not requiring oxygen Lactic acid – an organic waste produced by anaerobic fermentation –Occurs during periods of intense exercise “side ache) Ethyl alcohol – a liquid waste produced by anaerobic fermentation –Occurs in yeasts when making bread and alcoholic beverages.

21. Controlling Respiration Feedback inhibition – process used by cells to control metabolic pathways –Too much of a substance creates a pathway to stop the production of the substance –Too little of a substance creates a pathway to increase production of a substance –Ex. - Hyperventilate, Hunger, Increased respiration during exercise

22. Photosynthesis Heterotrophs – organisms that cannot make their won food and must obtain energy from the foods they eat Autotrophs – a self-nourishing organism that makes its own food Photosynthesis – process by which autotrophs harvest energy to make glucose 6CO 2 + 12H 2 O + light  C 6 H 12 O 6 + 6O 2 + 6H 2 O

23. Leaf Anatomy Stoma – an opening on the underside of a leaf for gas exchange Vascular bundle – a vein in a leaf that transports water and food Mesophyll – the green tissue inside a leaf Chlorophyll – the pigment that absorbs light in autotrophs

24. Leaf Anatomy Mesophyll Stoma Vascular Bundle Top Layer

25. Light Absorption

26. The first step in photosynthesis is the absorption of light energy Plant cells convert energy from light to chemical energy; called the light reaction Produces ATP and NADPH

27. Light Reaction

28. Electrons gain energy when light strikes chlorophyll. Excited electrons transferred to a reaction center and enter an electron transport chain. An assembly of proteins and pigments through which electrons are transferred to reaction centers is called a photosystem

29. Light Reaction Photosystem I – chlorophyll absorbs red light and produces ATP; electrons return to reaction center Photosystem II – chlorophyll absorbs red light and moves electrons to Photosystem I; electrons are replaced by the splitting of water and oxygen is released Energy enriched electrons produce ATP by adding a phosphate to ADP No glucose is produced after the light reaction.

30. Dark Reaction (Calvin Cycle) The first step of the Calvin cycle, CO 2 molecules combine with the sugar RuBP (ribulose bisphosphate) to make PGA (phophosglycerate). –The source of carbon in photosynthesis is CO 2 in the air. The second step of the Calvin cycle, energy from ATP combines with electrons from NADPH to form G3P, and energy rich sugar molecule.

31. Dark Reaction (Calvin Cycle) The third step of the Calvin cycle, G3P produces glucose and other compounds needed for growth and metabolism. The fourth step of the Calvin cycle, energy from ATP is added to G3P to make RuBP. The cycle is complete and begins again.

32. Dark Reaction (Calvin Cycle)

33. Making Glucose in Difficult Conditions C 4 plants – a plant that photosynthesizes in hot, dry weather –Special enzymes convert CO 2 into a four- carbon compound –Ex. corn and crabgrass CAM plants – a plant that takes in CO 2 only during the night. –Open stomata at night and store CO 2 for use in the day –Ex. Cacti and pineapple