U2 Cellular Energy

Cellular Energy PPT

1. Unit 2 Cellular Energy Photosynthesis & Respiration

2. Energy Energy is the ability to do work. Thermodynamics is the study of the flow and transformation of energy in the universe. 1 st Law – energy can be converted from one form to another, but it cannot be created nor destroyed. 2 nd Law – energy cannot be converted without the loss of usable energy.

3. Autotrophs vs. Heterotrophs Use light energy from sun to make own food Obtain energy from other organisms ALL ORGANISMS NEED ENERGY TO CARRY OUT LIFE FUNCTIONS (reproduction, repair, growth, development, movement) AND MUST RELEASE ENERGY FROM SUGARS AND OTHER COMPOUNDS!!

4. Cellular Energy Processes Photosynthesis – light energy from the Sun is converted to chemical energy for use by the cell. Cellular Respiration – organic molecules (such as glucose) are broken down to release energy for use by the cell.

5. Photosynthesis Photosynthesis is the process by which the solar energy of sunlight is converted into the chemical energy of glucose by producers such as plants, algae (protists) and some bacteria.

6. Photosynthesis Photosynthesis occurs in the cell organelle called the chloroplasts . Chloroplasts contain thin, disk-like structures called thylakoids . The space/substance surrounding the thylakoids is called the stroma .

7. Photosynthesis Chlorophyll is the pigment inside the thylakoid of chloroplasts, that absorbs light for photosynthesis (and makes the plant green). Other pigments include the colors red, orange, and yellow.

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9. Electron Carriers When a potato is very hot, you wouldn’t dare grab it with your bare hand, rather you use an oven mitt to carry the potato. As the potato cools, you no longer need the oven mitt. This is similar to an electron carrier. Once an electron receives energy from the sun, it is considered a “high-energy electron.” The electron does not travel on its own from place to place. Another substance (in this case NADP) carries the electron to its destination. As the electron loses it’s high energy levels, it no longer needs an electron carrier. An electron carrier then is “a compound that can accept a pair of high-energy electrons and transfer them, along with most of their energy, to another molecule.” NADP + / NADPH = electron carrier

10. Photosynthesis Photosynthesis occurs in two phases: Light-dependent Reactions H 2 0 is broken down and light energy is stored temporarily in inorganic energy carriers, ATP and NADPH Light-independent Reactions (Calvin Cycle) Energy is transferred from ATP and NADPH to the organic compound glucose

11. Photosynthesis Light-dependent Reactions Require light and H 2 O Occurs in the thylakoid membrane Use energy from light to produce O 2 and convert ADP and NADP+ into the energy carriers ATP and NADPH.

12. Photosynthesis Light-independent Reactions Does NOT require light Occurs in the stroma Uses ATP and NADPH from light-dependent reactions (and CO 2 from the environment) to produce high-energy sugars that can be stored for a long time.

13. Summary of Photosynthesis H 2 O O 2 Glucose H 2 O ATP & H + CO 2 Light-dependent Reaction Light-independent Reaction Light

14. Factors that Affect Photosynthesis Light Intensity Temperature Water and Carbon Dioxide levels

15. Alternate Pathways In hot, dry environments plants have adapted to a different way to perform photosynthesis: C 4 Plants Able to make glucose in different cells. Ex: Corn and Sugarcane CAM Plants Are able to make glucose at different time of the day. Ex: Pineapples and Cacti

16. Cellular Respiration Cellular respiration is the process by which the energy of glucose is released in the cell to be used for life processes. Respiration occurs in ALL CELLS! The equation for cellular respiration is the opposite of the equation for photosynthesis.

17. Cellular Respiration Types of Respiration Aerobic Respiration – requires oxygen Anaerobic Respiration – uses no oxygen

18. Aerobic Respiration Occurs in the mitochondria of the cell Total of 34-36 ATP molecules are produced 3 stages of aerobic respiration Glycolysis Krebs Cycle Electron Transport Chain & Chemiosmosis (34-36 ATP)

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20. Aerobic Respiration Glycolysis Occurs in the cytoplasm of the cell This stage occurs in both aerobic and anaerobic respiration because oxygen is not required! Glucose breaks down into 2 pyruvate 2 ATP are produced

21. Aerobic Respiration Glycolysis Inputs Outputs 1 glucose 2 ATP (needed to start) 2 pyruvates (go to Krebs) 4 ATP (2 are gained) 2 NADH (go to ETC)

22. Aerobic Respiration Krebs Cycle Occurs in the mitochondria A series of reactions occur (not just one step) Main purpose is to generate electrons of use in the electron transport chain (ETC) 2 ATP is given off

23. Aerobic Respiration Krebs Cycle Inputs Outputs 2 pyruvate 2 ATP 6 NADH (go to ETC) 2 FADH 2 (go to ETC) 4 CO 2 (given off as waste)

24. Aerobic Respiration Electron Transport Chain (ETC) and Chemiosmosis Occurs in the inner membrane of mitochondria Series (chain) of coupled reactions (electrons are transported through the chain) Electrons carried to this step by NADH and FADH 2 (produced in Kreb’s Cycle) Oxygen is used in this step Water is given off

25. Aerobic Respiration Electron Transport Chain and Chemiosmosis Inputs Outputs 8 NADH 2 FADH 2 Oxygen 32 ATP H 2 O

26. Aerobic Respiration Where do we get 36 ATP? 2 ATP made in glycolysis 2 ATP made in Krebs Cycle 32 ATP made in ETC

27. Anaerobic Respiration Also called fermentation! Uses Glycolysis Yields 2 pyruvate and 2 ATP With no oxygen present, cellular respiration does not occur. ONLY 2 ATP ARE PRODUCED (compared to aerobic respiration) 2 types of fermentation: Alcoholic Fermentation Lactic Acid Fermentation

28. Anaerobic Respiration Alcoholic Fermentation Lactic Acid Fermentation Pyruvate converted to ethyl alcohol, CO 2 and 2ATP Carried out by yeast and some bacteria Used in producing alcohol (both consumable and for ethanol), and for baking Pyruvate converted to lactic acid and 2 ATP Carried out by muscles when working hard (muscles need ATP but can’t get O2) Causes muscle soreness and cramps

29. 30 Glycolysis Pyruvic acid 2 ATP Anaerobic Aerobic Lactic Acid Fermentation Alcoholic Fermentation Lactic Acid 2 ATP Ethyl Alcohol, CO 2 , 2 ATP In cytoplasm Electron Transport Chain 32 ATP Kreb’s Cycle 2 ATP 36 ATP, CO 2 & H 2 O Cellular Respiration Summary

30. 31 Characteristic Inputs 1 st step Uses oxygen? Cell location Outputs Number of ATP produced Net Gain of ATP Aerobic Respiration Glucose Glycolysis Yes Mitochondria CO 2 , H 2 O, energy (ATP) 38 ATP 36 ATP Lactic Acid Fermentation Glucose Glycolysis No Cytoplasm Lactic acid, ATP 4 ATP 2 ATP Alcoholic Fermentation Glucose Glycolysis No Cytoplasm Ethyl alcohol, CO 2 , ATP 4 ATP 2 ATP Cellular Respiration Summary

31. Factors that Affect Cellular Respiration Temperature Oxygen levels

32. Adenosine Triphosphate (ATP) ATP is one of the principal chemical compounds that cells use to store and release energy. ATP powers all cellular work! Ribose (sugar) 3 Phosphate groups Adenine (base)

33. Cycling of ATP How is energy stored and released in a cell? All energy is stored in the bonds of compounds – breaking the bond releases the energy. When the cell has energy available it can store this energy by adding a phosphate group to ADP, producing ATP.

34. Cycling of ATP ATP is converted into ADP by breaking the bond between the second and third phosphate groups and releasing “stored” energy for cellular processes. ATP + H 2 O  ADP + P + ENERGY