Chapter 9 Cellular Respiration

9-1 Chemical Pathways Food provides living things with the chemical building blocks they need to grow and reproduce. Chemical Energy and Food - One gram of Glucose – 3811 calories of heat energy when burned ( C) - One gram of Glucose – 3811 calories of heat energy when burned ( C) calorie – energy needed to raise one gram of water one degree C ◦ (1C=1000 c) Glycolysis releases only a small amount of energy.

Flow of Cellular Respiration

A. Overview of Cellular Respiration 1. In the presence of oxygen Glycolysis is followed by the Krebs cycle and the Electron Transport Chain 2. Cellular Respiration – process that releases energy by breaking down glucose and other food molecules in the presence of Oxygen. 6O 2 + C 6 H 12 O 6 --> 6CO 2 + 6H 2 O + energy 6O 2 + C 6 H 12 O 6 --> 6CO 2 + 6H 2 O + energy

3. CR cannot take place in one step, because it would release all the energy at once, mostly in the form of light and heat. 4. There are three main stages of CR A. Glycolysis B. Krebs Cycle C. ETC – Electron Transport Chain

Checkpoint! 1. How is a calorie of energy measured? a. 1 cal can raise one ounce of water one degree C ◦ b. 1 cal can raise ten grams of water one degree C ◦ c. 1 cal can raise one gram of water one degree C ◦ d. 1 cal can raise one gram of water ten degree C ◦ 2. What is the first step in CR? a. Krebs Cycles b. Glycolysis c. Electron Transport Chain d. Fermentation

B. Glycolysis 1. Glycolysis- breaking down of one molecule of glucose into two molecules of pyruvic acid 2. ATP production – a. 2 molecules of ATP used to get reaction started b. 4 ATP molecules produced by the end Net Gain ATP molecules

3. NADH Production a. NAD + - electron carrier b. becomes NADH when the molecule is full of high energy electrons and H+ 4. Advantages of Glycolysis - fast and can produce thousands of ATP in milliseconds - fast and can produce thousands of ATP in milliseconds - Does not require O 2 - Does not require O 2

C. Fermentation 1. Fermentation – process that follows glycolysis if O 2 is not present 2. Anaerobic – does not require oxygen a. NADH passes high energy electrons to back to pyruvic acid a. NADH passes high energy electrons to back to pyruvic acid b. this allows glycolysis to keep happening b. this allows glycolysis to keep happening

Checkpoint! 1. What is the starting molecule for glycolysis? a. oxygen b. glucose c. carbohydrate d. CO 2 2. What is the electron acceptor for glycolysis? a. NADPb. NAPDc. NAD + d. NADPH 3. Fermentation occurs in the absence of O 2 … it is called a. aerobic b. anaerobic c. oxygenic d. non-oxygenic a. aerobic b. anaerobic c. oxygenic d. non-oxygenic

D. 2 Types of Fermentation 1. Alcoholic Fermentation – Pyruvic acid + NADH --> alcohol +CO 2 +NAD + (Produces CO2 as well as alcohol)

2. Lactic Acid Fermentation a. pyruvic acid can accumulate and convert to lactic acid b. regenerates NAD+ so that glycolysis can continue pyruvic acid + NADH --> lactic acid + NAD + pyruvic acid + NADH --> lactic acid + NAD +

9-2 The Krebs Cycle and Electron Transport Chain - 90 % of the energy from glucose is still unused in pyruvic acid – in the electrons - Aerobic – with oxygen - world’s best electron receptor - Energy releasing pathways require oxygen – therefore this is why we breathe - Energy releasing pathways require oxygen – therefore this is why we breathe

A. Krebs Cycle

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