Cellular Respiration

1. Cellular Respiration • Overall reaction: A good cellular respiration animation! click above!

2. 3 stages of Cellular Respiration • Glycolysis - occurs in cytosol • Krebs Cycle – occurs in mitochondrion • Electron Transport – occurs in mitochondrion

3. ATP

4. Mitochondrion Electron micrograph of a mitochondrion in the pancreas of a bat.

5. 3D drawing of a mitochondrion

6. Glycolysis

7. Intermediate Reaction- Conversion of pyruvic acid to acetyl CoA in a mitochondrion- some references include this step at the end of glycolysis or at the start of Krebs Cycle

8. Krebs Cycle (sometimes called the Citric Acid Cycle)

9. How complex is the Kreb’s Cycle?

10. Another diagram of Krebs Cycle

11. Electron Transport Chain

12. Biosynthesis

13. Questions 1-3, page 102 • How are ATP and ADP related? • High-energy ATP molecules are converted into lower-energy ADP molecules when phosphate is removed and energy is released. ADP is converted back into ATP by the addition of a phosphate. • What types of molecules are broken down to make ATP? Which are most often broken down to make ATP? • Carbohydrates, lipids and proteins: Lipids and carbohydrates are the main source of ATP. • How are some organisms able to survive without sunlight and photosynthesis? • Chemosynthetic organisms use chemicals from their environment to make high-energy carbon-based molecules.

14. Questions 4-6 • Describe how you do not get energy directly from the food that you eat. • Food is not directly used for energy, but it is broken down to make ATP, which provides energy. • Compare and Contrast - How are the energy needs of plant cells similar to those of animal cells? How are they different? • Both plants and animals use ATP to power cell functions. Plants make their own food to be broken down to make ATP. Animals must consume other organisms for the food that is broken down to make ATP. • Chemical Reactions - A water molecule is added to an ATP molecule to break down ATP into ADP and a phosphate group. Write the chemical equation that represents this reaction. • H20 + ATP -> ADP + Pi

15. Questions 1-2, page 115 • How are cellular respiration and glycolysis related? • Glycolysis breaks down glucose in the cytoplasm before cellular respiration occurs in the mitochondrion. The aerobic processes in mitochondria use the products of glycolysis. • Summarize the aerobic stages of cellular respiration. Be sure to discuss the Krebs cycle and electron transport chain in your answer. • Answers should indicate that the products of glycolysis are broken down by the Krebs Cycle to make energy-carrying molecules and carbon dioxide. Energy from the Krebs Cycle is used by the Electron Transport Chain to make ATP.

16. Questions 3-4, page 115 • Analyze – Describe the relationship between cellular respiration and photosynthesis. Discuss the functions of chloroplasts and mitochondria. • The reactant and products of the overall processes are essentially the reverse of each other. The chloroplasts and mitochondria also have approximately opposite functions. Chloroplasts absorb energy and build carbon-based molecules and mitochondria break down carbon-based molecules to release energy. • Apply – Is glucose a reactant in the aerobic stages of cellular respiration? Explain. - No, glucose is broken down during glycolysis, which is an anaerobic process.

17. Question 5, p115 • Chemical Reactions – Is the process of cellular respiration exothermic or endothermic? Explain your answer. • Exothermic – energy is released as heat and ATP.

18. Questions 1-3, p 121 • What is the role of pyruvate in cellular respiration? • pyruvate, produced by the breakdown of glucose, is needed for the Krebs Cycle, which is part of cellular respiration. • Describe in your own words the function of the Krebs Cycle. • The Krebs Cycle breaks down and extracts energy from carbon-based molecules, transfers it to the electron transport chain, makes a small amount of ATP, and releases carbon dioxide. • Explain the functions of electrons, hydrogen ions, and oxygen in the electron transport chain. • The electron transport chain pumps hydrogen ions across the inner mitochondrial membrane. Hydrogen ions then flow through a channel that is bound to ATP synthase. Oxygen picks up electrons and hydrogen ions so that the electron transport chain can continue to function.

19. Questions 4-6 p 121 • Compare and Contrast – Describe the similarities and differences between the Krebs Cycle and the Calvin Cycle. • Both occur in the interior space of their respective organelles, and both are cycles of chemical reactions. The Calvin Cycle builds larger carbon-based molecules in chloroplasts to store energy. The Krebs Cycle breaks down carbon-based molecules in the mitochondria to release energy. • Evaluate – Is oxygen necessary for the production of all ATP in your cells? Why or why not? • No, ATP is also formed during glycolysis, which can continue without oxygen. • Common Ancestry – Protein molecules called cytochromes are part of the electron transport chain. They are nearly identical in every known aerobic organism. How do these molecules show the unity of life on Earth? • The similarity of cytochromes in many different organisms suggests a common ancestor.

20. Questions 1-3, p 125 • What is the relationship between glycolysis and fermentation? • Glycolysis leads to fermentation if no oxygen is available. NAD+ produced by fermentation allows glycolysis to continue. • Summarize the process of alcoholic fermentation in yeast. • Sugars are broken down by glycolysis. Pyruvate and NADH enter alcoholic fermentation, producing alcohol and carbon dioxide. NAD+ is recycled back to glycolysis. • Compare and Contrast – How are lactic acid fermentation and alcoholic fermentation similar? How are they different? • Both are anaerobic processes that break down glucose to make ATP and recycle NAD+ to glycolysis. Lactic acid fermentation produces lactic acid; alcoholic fermentation produces alcohol and carbon dioxide.

21. Questions 4 & 5 • Compare and Contrast – Describe the similarities and differences between cellular respiration and fermentation. • Both produce ATP through the breakdown of carbon-based molecules, and both allow glycolysis to continue by recycling electron acceptors. Cellular respiration requires oxygen and produces much more ATP than fermentation. • Aerobic Respiration – How is the role of oxygen in cellular respiration similar to the role of NAD+ in fermentation? • Both oxygen and NAD+ pick up electrons and allow ATP production to continue.

22. Fermentation • In the absence of oxygen, entire process of cellular respiration stops (oxygen is a final electron acceptor). See – page 409 – BSCS • During strenuous exercise, muscles may not get enough O2, thus fermentation occurs. • Lactic Acid Fermentation - pyruvic acid produced in glycolysis converted into lactic acid (and NADH gives up hydrogen atoms to become NAD+ (goes back to glycolysis) • Lactic acid – produces muscle stiffness. As muscles recover, lactic acid is converted back to pyruvic acid (cellular respiration continues)

23. Fermentation - continued • Lactic acid bacteria can ferment milk sugar lactose to lactic acid (help make yogurt) • Alcohol fermentation – yeast cells, in the absence of oxygen, convert pyruvic acid from glycolysis into ethanol and carbon dioxide • Bread making – CO2 produces the air pockets in the bread, causes bread to leaven (rise) • Production of Alcohol – making beer, wine, etc. – ethanol produced, along with CO2 (the bubbles) • Fermentation is helpful in the industrial production of various useful products such as alcohol, antibiotics, vitamins, organic acids, bakery and dairy products, tanned leather, etc.

24. Photosynthesis Overall Reaction:

25. Chloroplasts

26. Photosynthesis Summary

27. Light Reaction Another good light reaction animation! One more!

28. Light Reaction Summary

29. Dark Reaction

30. More complicated illustrations of the Dark Reaction

31. Plant Biosynthesis

32. Great Biology Animations • Light Reaction • Another Light Reaction animation • Dark Reaction (Calvin Cycle) – see top link!!

33. Questions 1-3, p 105 • What are the roles of chloroplasts and chlorophyll in photosynthesis? • Photosynthesis occurs in chloroplasts, powered by energy captured by chlorophyll. Chlorophyll is a light-absorbing molecule located in chloroplasts. • Describe the stages of photosynthesis. Use the terms thylakoid, light-dependent reactions, and light-independent reactions in your answer. • The first stage of photosynthesis is the light-dependent reaction that takes place in the thylakoids. Energy is absorbed from sunlight and transferred through the thylakoid membrane. The energy is used in the light-independent reactions to produce sugars. • Apply – Supposed you wanted to develop a light to increase plant growth. What characteristics should the light have? Why? • The light should emit the optimal wavelengths, such as blue and red, to be absorbed by the pigments of the plants.

34. Questions 4-5, p 105 • Analyze – Explain why photosynthesis is important for building the structure of plants cells. • In plants, the cell wall is responsible for structure and support. Cell walls are made from cellulose, which is a carbohydrate that is built up from sugars produced during photosynthesis. • Chemical Reactions – Overall, do you think photosynthesis is endothermic or exothermic? Explain your answer. • Endothermic – it absorbs energy to produce sugars.

35. Questions 1-3, p 112 • How do the two photosystems work together to capture energy from sunlight? • Photosystems II absorbs energy and energizes electrons. The electrons are passed along to photosystem I, which absorbs more energy and adds it to the electrons. • Explain the relationship between the light-dependent and light-independent reactions. • The light-dependent reactions absorb energy from sunlight and transfer the energy to the light-independent reactions that produce sugars. • Connect – Explain how the Calvin Cycle is a bridge between carbon in the atmosphere and carbon-based molecules in the food you eat. • Carbon dioxide is removed from the atmosphere by plants for photosynthesis. The carbon is incorporated into sugars and other carbon-based molecules that are eaten by other organisms.

36. Questions 4-5, p 112 • Explain why the chemical equation for photosynthesis (below) is a highly simplified representation of the process. How is the equation accurate? How is it inaccurate? • 6CO2 + 6H2O → C6H12O6 + 6O2 • The equation shows the general reactants and products in the process. However – it does not show intermediate steps. For example, water and carbon dioxide do not actually react with each other. • Cell Functions – Explain how both passive transport and active transport are necessary for photosynthesis to occur. • Active transport moves the hydrogen ions against the concentration gradient in photosystem II. Passive transport occurs when hydrogen ions flow through the channel bound to ATP synthase.