KREBS CYCLE & ELECTRON TRANSPORT Chapter 9-2

Transcription

1 KREBS CYCLE & ELECTRON TRANSPORT Chapter

2 REMEMBER: The fork in the road happens following glycolysis. The presence or absence of OXYGEN decides which path it takes next.

3 Flowchart Section 9-2 Cellular Respiration Glucose (C 6 H ) + Oxygen (0 2 ) Glycolysis Krebs Cycle We will next focus on the Krebs Cycle. This is the path that is taken when oxygen is present.

4 Image from BIOLOGY Miller and Levine; Prentice Hall Publishing KREBS CYCLE follows glycolysis if oxygen is present

5 REMEMBER: Glycolysis happens in the CYTOPLASM outside the mitochondria. Krebs cycle happens in MATRIX inside the mitochondria

6 PYRUVIC ACID (also called pyruvate) enters the MITOCHONDRION Pyruvic acid joins with COENZYME A to form ACETYL - CoA Diagram by Riedell

7 WHERE DO THESE GO? Carbon dioxide is released into the atmosphere High energy electron carriers move into the ELECTRON TRANSPORT CHAIN (We will come back to this later)

8 Citric Acid Formation: Krebs Cycle Animation-(select #2) 2 carbon ACETYL-COA combines with a 4 carbon molecule to form a 6-carbon molecule called citric acid.

9 WHERE DO THESE GO? Coenzyme A goes back to pick up another Pyruvic acid Citric acid completes the KREBS CYCLE

10 KREBS CYCLE Krebs Cycle Animation-(select #3) KREBS CYCLE PRODUCES

11 WHERE DOES IT GO? 6 carbons in original glucose are lost as Carbon dioxide to atmosphere

12 WHERE DO THESE GO? ATP can be used directly to supply energy for the cell. High energy electron carriers move into the ELECTRON TRANSPORT CHAIN

13 Flowchart Section 9-2 Cellular Respiration Glucose (C 6 H ) + Oxygen (0 2 ) Glycolysis Krebs Cycle Electron Transport Chain We will next focus on the Electron Transport Chain.

14 WHERE DOES IT HAPPEN? Glycolysis KREBS ET Enzymes for ELECTRON TRANSPORT CHAIN are located in the Inner mitochondrial membrane (cristae)

15 ELECTRON TRANSPORT CHAIN INTERMEMBRANE SPACE CRISTAE MATRIX Image from: BIOLOGY by Miller and Levine; Prentice Hall Publishing 2006

16 Electron Transport Chain: Electron Transport Chain Animation- (select start, continue, and #1) High-energy electrons from NADH and FADH 2 are passed along the electron transport chain. Energy from passing electrons is used to transport Hydrogen ions (H + ) across the membrane.

17 Electron Transport Chain: Electron Transport Chain Animation- (select start, continue, and #3) The pumping of H + ions into the INTERMEMBRANE SPACE represents potential energy that is harnessed to make ATP. As H + ions escape through ion channels back into the matrix, ATP SYNTHASE spins and adds a phosphate to ADP to form ATP

18 Electron Transport Chain: OXYGEN serves as the final electron acceptor of the electron transport chain. At the end of the electron transport chain, an enzyme combines the electrons with the hydrogen ions and oxygen to form water (H 2 O)

19 Electron Transport Chain Animation-(#1 and #2) High-energy electrons from NADH come in at beginning but electrons from FADH 2 come in farther down the chain.

20 SO: NADH 3 ATP s 2 ATP s FADH 2

21 Figure 9 2 Cellular Respiration: An Overview WHATS THE BIG PICTURE? Electrons carried in NADH Pyruvic acid Electrons carried in NADH and FADH 2 Glucose Glycolysis Krebs Cycle Electron Transport Chain Cytoplasm Mitochondrion

22 CELLULAR RESPIRATION includes: GLYCOLYSIS KREBS CYCLE ELECTRON TRANSPORT CHAIN

23 GLYCOLYSIS Happens in CYTOPLASM outside mitochondria Breaks down 1 glucose into 2 pyruvic acid (pyruvate) Produces 2 2

24 KREBS CYCLE happens in MATRIX Breaks down Produces: inside mitochondria 2 pyruvic acid

25 ELECTRON TRANSPORT cristae Enzymes found in inner membrane of mitochondria Uses high energy electrons and H + ions donated by NADH and FADH 2 Makes 32 (net) ATP OXYGEN acts a final electron acceptor to produce H 2 O

26 Image from BIOLOGY Miller and Levine; Prentice Hall Publishing

27 CELLULAR RESPIRATION (aerobic/ with oxygen): 1 glucose 36 ATP FERMENTATION (anaerobic/ without oxygen): 1 glucose 2 ATP

28 Remember! CARBOHYDRATES SUPPLY ENERGY Cells burn GLUCOSE for their energy needs Images from:

29 EXERCISE and ENERGY (Short term energy) SMALL Cells normally contain amounts of ATP produced by GLYCOLYSIS & CELLULAR RESPIRATION (only enough for a few seconds of activity) LACTIC ACID Once this ATP is used up fermentation can provide enough ATP to last about. 90 seconds

30 EXERCISE and ENERGY (Short term energy) Once race is over, Lactic acid must be broken down using oxygen. Well trained athletes burn lactic acid more efficiently. Image from:

31 EXERCISE and ENERGY (LONGER term energy) For exercise longer than 90 seconds Cellular respiration is the only way to make enough ATP. Cellular respiration releases energy more slowly than fermentation. Well conditioned athletes must pace themselves during a long race.

32 What happens in a long race when the body s glucose all is used up? Animal cells store GLUCOSE as GLYCOGEN REMEMBER to use later. Image from:

33 EXERCISE and ENERGY (LONGER term energy) MUSCLES store glucose glycogen as which can be broken down into glucose to supply energy for minutes of activity.

34 EXERCISE and ENERGY (LONGER term energy) After glycogen stores are used up the body begins to break down FAT That s why aerobic exercise must continue for longer than 20 minutes if you want to lose weight! Image from:

35 ALL CELLS NEED ENERGY Eukaryotes All (including plant and animal cells) have for cellular respiration mitochondria All Prokaryotes (bacteria) have their electron transport enzymes attached to their Cell membranes Remember: No membrane bound organelles!