Cellular Respiration Notes. Biology - Mrs. Kaye

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1 Cellular Respiration Notes Biology - Mrs. Kaye

2 Energy Transfer In cellular respiration, chemical energy is converted into usable energy which is converted into heat energy.

3 ATP and ADP ATP acts as an energy carrier that stores, releases, and converts energy to a usable form for cells. The energy in ATP is found in the bonds connecting the phosphate groups. To release energy from ATP, the last phosphate group needs to break free, turning ATP into ADP.

4 Energy Production - ATP: The Ultimate Energy Source Carbon dioxide and water are byproducts that we release as we exhale. ATP is the energetic push that starts reactions in cells. When the body needs more energy, mitochondria detect increased ADP levels and respond by increasing the rate of respiration.

5 Energy Production - ATP: The Ultimate Energy Source The presence or absence of oxygen in cells determines the fate of pyruvate. With oxygen, about 38 ATP are made per molecule of glucose. Without oxygen, 2 ATP are made with alcohol, or lactic acid in muscles.

6 Supply and Demand When there is a high demand of energy needed (during exercise), sugar is rapidly absorbed from the blood into cells. The liver breaks down glycogen into glucose to restore the blood levels.

7 Supply and Demand When there is a low demand of energy needed (during rest), cells use excess glucose to make glycogen in the liver then convert it to fat.

8 Cellular Respiration Cellular respiration - the series of chemical reactions by which a living cell breaks down food molecules and obtains energy from them. Potential energy in food molecules must be converted into a usable form. Enzymes convert energy stored in macromolecules (starch/glycogen) or small molecules (glucose) into a usable form of ATP.

9 Cellular Respiration C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + 38 ATP Glucose Oxygen Carbon Dioxide Water Energy

10 Cellular Respiration Cellular respiration begins in the cytoplasm of cells and continues into the mitochondria.

11 Cellular Respiration

12 The Three Stages of Cellular Respiration 1. Glycolysis - the initial breakdown of a carbohydrate, usually glucose, into smaller molecules at the beginning of cellular respiration. 2. Krebs cycle - the energy-releasing cycle in cellular respiration that completes the breakdown of intermediate products of glycolysis.

13 The Three Stages of Cellular Respiration 3. Electron Transport System (Chain) - the process in which electrons are transferred from one carrier molecule to another in photosynthesis and in cellular respiration.

14 Glycolysis Glycolysis takes place in the cytoplasm of a cell. Oxygen is not required for this process. Glyco = sugar; lysis = split. Glucose (sugar) is broken down into 2 pyruvate molecules. Pyruvate - an organic molecule consisting of a 3-carbon backbone.

15 Glycolysis - The Fate of Pyruvate If oxygen is not present (anaerobic), glycolysis will continue and the pyruvate molecules will take part in fermentation. Anaerobic respiration - respiration that does not require oxygen.

16 Glycolysis - The Fate of Pyruvate If oxygen is present (aerobic), pyruvate will move to the Krebs cycle and Electron Transport System. Aerobic respiration - respiration that requires oxygen.

17 Glycolysis - Fermentation Fermentation - a metabolic process that consumes sugar in the absence of oxygen. Lactic acid fermentation occurs in animals and humans and produces energy. Alcoholic fermentation is used by yeast to produce energy.

18 Glycolysis - Lactic Acid Fermentation During exercise, oxygen (O 2 ) is not supplied fast enough and pyruvic acid is converted to lactic acid. After exercise, oxygen (O 2 ) is still needed to convert lactic acid back into pyruvic acid.

19 Glycolysis - Lactic Acid Fermentation Some organisms get energy from this process; we use lactic acid to make cheese, yogurt, and sour cream. In muscles, lactic acid builds up and causes eventual fatigue.

20 Glycolysis - Alcoholic Fermentation Pyruvic acid is converted into ethyl alcohol and carbon dioxide (CO 2 ). Yeast use alcoholic fermentation to obtain energy (ATP). Humans use yeast to make bread and alcoholic beverages.

21 Glycolysis - Products 2 molecules of ATP. 2 molecules of NADH. NADH - a high energy molecule used by cells to generate ATP. These will be carried away to be used later in the Electron Transport System.

22 The Krebs Cycle The Krebs cycle takes place in mitochondria. Oxygen is required for this process. The reactions in this process release most of the remaining energy in pyruvate by using enzymes to convert pyruvate into a 2-carbon molecule by removing a molecule of CO 2.

23 The Krebs Cycle Acetyl-CoA from pyruvate combines with a 4-carbon molecule. A 6-carbon molecule is formed (citric acid). The 6-carbon molecule is broken down into a 5-carbon molecule and then into a 4-carbon molecule. CO 2 is released at each step. The 4-carbon molecule is available to combine with new acetyl-coa that enters the cycle.

25 The Krebs Cycle - Products 6 molecules of CO 2. 2 ATP. 10 NADH.

26 The Electron Transport System This is the final step in the cellular respiration process; also called the Electron Transport Chain. Oxygen is required. Hydrogen atoms, containing 1 electron (e - ) and 1 proton (p + ), carried by NADH are separated into electrons and protons (H + ). The electrons join with oxygen and protons to form water (H 2 O) and the flow of protons makes ATP.

27 The Electron Transport System

28 The Electron Transport System - Products 34 ATP. 6 molecules of H 2 O.

Cellular Respiration. How our body makes ATP, ENERGY!!

Cellular Respiration. How our body makes ATP, ENERGY!! Cellular Respiration How our body makes ATP, ENERGY!! Useable Energy Adenosine Tri-Phosphate (ATP) Adenosine Ribose Sugar 3 Phosphates November 27, 2017 November 27, 2017 Where do our cells get energy?