Cellular Respiration

1. Cellular Respiration • LO’s • Able to understand the processes of glycolisis, the citric acid cycle, krebs cycle and electron transport system. • Able to compare between photosynthesis and cellular respiration

2. Cellular Respiration • Process that unlocks stored energy • Nutrient molecules store energy in bonds • Chemical reactions produce ATP • ATP provides cellular energy Skunk cabbage using metabolic heat to melt snow

3. ATP • ATP powers cellular work • A cell does three main kinds of work: • Mechanical work, beating of cilia, contraction of muscle cells, and movement of chromosomes • Transport work, pumping substances across membranes against the direction of spontaneous movement • Chemical work, driving endergonic reactions such as the synthesis of polymers from monomers

4. The bonds between phosphate groups can be broken by hydrolysis.

5. So what? • Energy is stored in these bonds. • So? • The breaking of the chemical bond releases the energy ATP + H2O→ ADP + P + ENERGY

6. Photosynthesis and cellular respiration – provide energy for life Photosynthesisis the process where green plants use sunlight, carbon dioxide, and water to make food and oxygen (chloroplasts- chlorophyll) 6CO2 + 6H2O + energy -->  6O2 + C6H12O6 • Cellular Respirationis the process where cells use this food to release stored energy (mitochondria) • takes glucose, breaks it down into atoms, and by mixing it with the atoms from more oxygen, produces carbon dioxide, water and energy ... A new energy is form and it can be used by all cells • 6O2 + C6H12O6 -->  6H2O + 6CO2 + energy (ATP) The theoretical maximum yield of cellular respiration is 36 ATP per molecule of glucose metabolized. 

7. Chemical Reactions for Photosynthesis • Light dependent reactions • Light independent reactions

8. Cellular respiration The process by which mitochondria break down glucose to make ATP

9. Cellular respirationmetabolic reactions /processes; to convert biochemical energy from nutrients into adenosina triphospahte (ATP), and then release waste products. ATP : covalent bonds between atoms 6O2 + C6H12O6 -->  6H2O + 6CO2 + energy (ATP) Glucose looses electrons and hydrogen and oxygen gains electrons and hydrogen During this process heat energy is released. This is a redox reaction; a chemical reaction that transfers electrons from one substance to another aka oxidation- reduction reactions. Oxidation is the loss of electrons during a redox reaction and reduction is the acceptance of electrons during a redox reaction. The reactions involved in respiration are catabolic reactions that involve the redox reaction (oxidation of one molecule and the reduction of another). Respiration is one of the key ways a cell gains useful energy to fuel cellular reformations.

10. Cellular Respiration - Aerobic respiration requires oxygen in order to generate energy (ATP) • Chemical reactions to yield energy • Break down carbohydrates • Series of reactions

11. Aerobic Cellular Respiration • Byproducts • Raw materials for photosynthesis • Carbon dioxide • Water • Oxygen dependent

12. Cellular respiration • Three metabolic processes: • Glycolysis - cytosol • Krebs cycle - takes place in the matrix of the mitochondria • Oxidative phosphorylation - via the electon transport chain is carried out on the inner mitochondrial membrane In the absence of oxygen, respiration consists of two metabolic pathways: glycolysis and fermentation. Both of these occur in the cytosol.

13. Glycolosis • Glyco = glucose Lysis = break down • Occurs in the cytoplasm • This stage occurs in BOTH aerobic and anaerobic respiration • Glucose breaks down into 2 pyruvate (2 ATP are also made) • Glucose is a 6-carbon sugar • Pyruvate is a 3-carbon molecule (there are two of them)

14. Glycolosis - glucose is split into pyruvic acid. Glucose, a six carbon sugar, is split into two molecules of a three carbon sugar. In the process, two molecules of ATP, two molecules of pyruvic acid and two "high energy" electron carrying molecules of NADH are produced. In the presence of oxygen, glycolysis is the first stage of cellular respiration. Without oxygen, glycolysis allows cells to make small amounts of ATP. This process is called fermentation. There are 4 important stages in Glycolysis: • Activation of glucose by ATP• Splitting of glucose into two roughly equivalent phosphorylated halves• Reduction of NAD+ to NADH• Phosphorylation of ADP

15. Reactants 1 glucose Enzymes are needed 2 ATP are needed to start Products 2 Pyruvates (go to next step) 4 ATP (2 are gained) 2 NADH (go to ETC) Glycolysis Reactants and Products

16. Intermediate step • Pyruvate is converted to acetyl CoA • Occurs in the cytoplasm • See diagram on simple explanation handout

17. Intermediate step Reactants and products Reactants • 2 pyruvate (from glycolysis) Products • 2 Acetyl CoA (go to next step) • 2 CO2 (given off as waste) • 2 NADH (go to ETC)

18. Krebs Cycle (Citric Acid Cycle) • Occurs in the matrix of mitochondria • A series of reactions occur (this is not just one step) • Main purpose is to generate electrons for use in ETC • 2 ATP is given off • See diagram on simple explanation handout

19. Krebs Cycle Reactants and Products Reactants • 2 Acetyl CoA Products • 2 ATP • 6 NADH (go to ETC) • 2 FADH2 (go to ETC) • 4 CO2 (given off as waste)

20. Electron Transport Chain • Occurs in inner membrane of mitochondria • Series (chain) of coupled redox reactions (electrons are transported through the chain) • Electrons carried to this step by NADH and FADH2 (produced in previous steps) • Oxygen is used in this step • Water is given off

21. Electron Transport Chain Reactants and Products Reactants • 10 NADH • 2 FADH2 • Oxygen Products • 34 ATP • H2O

22. Where do we get 38 ATP? • 2 ATP made in glycolysis • 2 ATP made in Krebs Cycle • 34 ATP made in ETC • 1 NADH = 3 ATP • 10 X 3 = 30 • 1 FADH2 = 2 ATP • 2 X 2 = 4

23. Anaerobic Respiration (Fermentation) Fermentation is the anaerobic harvest of food energy. Anaerobic respiration occurs when your cells need more ATP than your bloodstream’s delivery of oxygen can supply. Common in yeast, molds, some bacteria Carbon & hydrogen not fully oxidized Less energy than aerobic respiration. It can produce 2ATP per glucose molecule. By oxidizing the NADH produced in glycolysis, fermentation regenerates NAD+, which can take part in glycolysis once again to produce more ATP.

24. Anaerobic Respiration (Fermentation) • Glycolysis • Yields 2 pyruvate and 2 ATP • With no oxygen present, cellular respiration does not occur • ONLY 2 ATP ARE PRODUCED (compare to aerobic respiration)

25. Two Types of Fermentation Alcoholic Fermentation • Pyruvate converted to ethyl alcohol and CO2 • Carried out by yeast and some bacteria • Used in producing alcohol (both consumable and for ethanol), and for baking Lactic Acid Fermentation • Pyruvate converted to lactic acid • Carried out by muscles when working hard (muscles need ATP but can’t get O2 ) • Causes muscle soreness and cramps

26. Photosynthesis • Carried out by most (not all) autotrophs • 6CO2 + 6H2O + light energy→ C6H12O6 + 6O2 • Basically this reaction is the OPPOSITE of cellular respiration • See simple explanation handout and text

27. Steps of Photosynthesis • Light reaction (depends on light) • Traps sunlight • Produces electrons and ATP required to power the dark reaction • Oxygen given off here • Dark reaction, aka Calvin Cycle (does not directly depend on light) • Uses ATP and electrons from light reaction and CO2 to make glucose See diagram on simple explanation handout

28. Cellular respiration - in presence of O2 • Yields • ATP from ADP • Carbon dioxide & water from glucose & oxygen

29. Three Phases Of Aerobic Cellular Respiration • Aerobic Cellular Respiration happens in Mitochondria. Three main reactions are involved: • Glycolisis occurs in cytoplasm of mitochondria (requires 2 ATP to start/ makes 2 ATP) • Krebs Cycle occurs in matrix of mitochondria (makes 2 ATP) • Electron Transport Chain occurs in mitochondria; makes majority of ATP (32 ATP) • Out of 38 ATP Produced - energy of 2 ATP required to start the process.