Chapter 9 Cellular Respiration

Transcription

1 Chapter 9 Cellular Respiration Electrons carried in NADH Mitochondrion Glucose Glycolysis Pyruvic acid Krebs Cycle Electrons carried in NADH and FADH 2 Electron Transport Chain Cytoplasm Mitochondrion Ms. Martinez

2 Athletes get the energy they need from the breakdown of glucose during cellular respiration.

3 Respiration Overview Living things get most of the energy they need from glucose. Autrotrophs make glucose using photosynthesis Heterotrophs get glucose from food they eat How? Cellular Respiration.

4 Cellular respiration is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen. The equation for cellular respiration is: 6O 2 + C 6 H 12 O 6 6CO 2 + 6H 2 O + Energy Oxygen + Glucose Carbon dioxide + Water + Energy

5 There are three stages of cellular respiration: Glycolysis Krebs Cycle Electron Transport Each of the three stages captures some of the chemical energy available in food molecules and uses it to produce ATP.

6 Glycolysis Stage #1 The process begins with a pathway called glycolysis. Glycolysis is the process in which a glucose molecule is split in half. Glycolysis takes place in the cytoplasm of a cell.

7 This forms two molecules of pyruvic acid, a 3-carbon compound.

8 Through glycolysis, the cell gains 4 ATP molecules or 2 net molecules. How? 4ATP 2ATP= 2 net ATP produced

9 In addition, the electron carrier NAD+ accepts a pair of high-energy electrons, producing NADH. By doing this, NAD+ helps pass energy from glucose to other pathways in the cell.

10 Glycolysis Summary Occurs in the cytoplasm 2 net ATP molecules are produced 2 pyruvic acid, 3- carbon, molecules are produced Does not require oxygen to occur

11 Mitochondria (plural) The mitochondrion (singular) is the organelle of Cellular Respiration. Mitochondria combine oxygen with food molecules to obtain energy, ATP molecule, for the cell.

12 In plant and animal cells, the second and third stages of cellular respiration take place in mitochondria. Mitochondria contain some DNA, the molecule that carries genetic information. A mitochondrion has two membranes.

13 The second stage of cellular respiration, the Krebs Cycle, take place in the matrix. The matrix is the inner compartment of the mitochondrion filled with about half water and half protein.

14 The third stage of cellular respiration, Electron Transport, takes place in the cristae. The cristae is the folded up inner membrane.

15 Mitochondrion Summary The mitochondrion is the only place in the cell where oxygen can be combined with food molecules to release the energy in them for use by the cell. Mitochondria contain some DNA. The second stage of cellular respiration, the Krebs Cycle, take place in the matrix. The third stage of cellular respiration, Electron Transport, takes place in the cristae.

16 Krebs Cycle Stage #2 Because the pathways of cellular respiration require oxygen, they are said to be aerobic. The term cellular respiration to refer to energy-releasing pathways within the cell that require oxygen.

17 During the Krebs cycle, pyruvic acid, 3 carbon molecule, is broken down into carbon dioxide in a series of energyextracting reactions. The Krebs cycle is also known as the citric acid cycle, because citric acid is one of its first products. The Krebs cycle occurs in the matrix. The matrix is the inner compartment of the mitochondrion filled with about half water and half protein.

18 Here are the stages of the Krebs cycle. The Krebs cycle starts when pyruvic acid formed by glycolysis enters the mitochondrion. This step requires oxygen. CO2

19 The pyruvic acid is broken down into carbon dioxide. The carbon dioxide is released as a waste product. The Krebs cycle continues in a series of reactions. CO2

20 In these reactions, two energy carriers, NAD+ and FAD+, accept highenergy electrons. NAD+ is changed to NADH, and FAD+ is changed to FADH2. These molecules carry the high-energy electrons to the electron transport chain.

21 Krebs Cycle Summary Requires oxygen. Pyruvic acid is the starting 3-carbon molecule. Carbon dioxide is the waste product. Occurs in the matrix. Produces some ATP.

22 Electron Transport Stage #3 The electron transport chain uses the high-energy electrons, NADH and FADH2, to change ADP into ATP. Electron Transport is known as the Energy Extraction phase since many ATP molecules are produced. It occurs in the cristae.

23 In the electron transport chain, high energy electrons move from one carrier protein to the next.

24 At the end of the chain, oxygen pulls electrons from the electron chain. Oxygen is the final electron acceptor. These electrons join with hydrogen ions, H+, forming water.

25 Each transfer along the chain releases a small amount of energy. ATP synthase uses the energy to produce ATP.

26 Electron Transport Summary Requires Oxygen. Uses the high-energy electrons, NADH and FADH2, to change ADP into ATP. Water is produced. Occurs in the cristae. Produces many ATP molecules.

27 Cellular Respiration Flowchart *From 1 molecule of glucose, up to 36 ATP molecules are made. 1 Glucose (C 6 H ) + Oxygen (0 2 ) Glycolysis CYTOPLASM Krebs Cycle MATRIX Carbon Dioxide (CO2) Released Electron Transport Chain CRISTAE Water (H2O) Formed 36 ATP produced

28 Electrons carried in NADH Mitochondrion Pyruvic acid Electrons carried in NADH and FADH 2 H2O Glucose Glycolysis Krebs Cycle Electron Transport Chain Cytoplasm CO2 Mitochondrion

29 Respiration vs. Photosynthesis The energy flows in photosynthesis and cellular respiration occur in opposite directions. On a global level, photosynthesis and cellular respiration are also opposites. Photosynthesis removes carbon dioxide from the atmosphere and puts back oxygen. Cellular respiration removes oxygen from the atmosphere and puts back carbon dioxide.