Breathing Is Only the Beginning Cellular Respiration Breathing Is Only the Beginning

Food Serves as source of materials for anabolic reactions in the body Serves as source of energy calorie: amount of energy needed to raise the temperature of 1 gram of water by 1-degree Celsius Calorie: used on food labels; amount of energy needed to raise the temperature of 1000 grams (1kg) of water by 1-degree Celsius

Cellular Respiration-An Overview Process that releases energy by breaking down glucose and other food molecules usually in the presence of oxygen

Cellular Respiration-An Overview 6O2 + C6H12O6 ---- > 6CO2 + 6H2O + energy Where in the cell is energy produced? Mitochondria What is the energy molecule in cells? ATP

Cellular Respiration-An Overview Three Stages Glycolysis Kreb’s Cycle Electron Transport Chain

Glycolysis The process of breaking one molecule of glucose (6C sugar) in half (2-3C sugars) to form pyruvic acid Needs 2 ATP molecules to start this reaction Forms 4 ATP molecules when completed

Glycolysis Releases 4 high energy electrons from glucose Does NOT require oxygen to occur Picked up by 2-NAD+ ions to form 2 NADH molecules that go to electron transport chain

Glycolysis

The Choice If oxygen is present in the cells what follows glycolysis is the Krebs Cycle thru aerobic cellular respiration If oxygen is not present in the cells what follows glycolysis is fermentation thru anaerobic cellular respiration

Kreb’s (citric acid) Cycle

Kreb’s (citric acid) Cycle 1-Pyruvic acid from glycolysis is broken down to carbon dioxide in a series of energy releasing reactions Produces 3-CO2 released as waste Produces 4-NADH and 1-FADH2 that goes to electron transport chain Produces 1-ATP

Electron Transport Chain Uses electrons from NADH (from glycolysis and Krebs Cycle) and FADH2 (from the Krebs Cycle) to make ATP from ADP

The Totals

The Totals

The Totals

The Totals

The Totals 1 molecule of glucose

Two Branches Fermentation Process of producing energy from pyruvic acid without the presence of oxygen Two Branches Alcoholic Lactic Acid

Alcoholic Fermentation Used by yeast and some other microorganisms Pyruvic acid + NADH ---- > ethyl alcohol + carbon dioxide + NAD+

Lactic Acid Fermentation Produces by muscle cells during rapid exercise Produces burning sensation in muscles since it is a muscle paralyzer Pyruvic acid + NADH ---- > lactic acid + NAD+

Lactic Acid Fermentation Produces by microorganisms as a defense against predators Pyruvic acid + NADH ---- > lactic acid + NAD+

Review Questions What is the difference between a calorie and a Calorie? Where does cellular respiration occur in the cell? What are the two reactants in cellular respiration? What are the three products? Name the three stages of cellular respiration. What is the starting chemical in glycolysis? What are the two products of glycolysis? Where do the electrons from the glucose molecules end up at the end of glycolysis? What chemical determines if glycolysis is followed by aerobic or anaerobic respiration? Why is breathing an important part of cellular respiration to animals?

Where does the pyruvic acid come from that starts the Kreb’s cycle? What are the products of the Kreb’s cycle? What are the products of the electron transport chain in cellular respiration? How is aerobic cellular respiration different from anaerobic cellular respiration? List at least two ways that alcoholic fermentation is different from lactic acid fermentation? Why do both types of fermentation produce NAD+? Where does the pyruvic acid come from that starts both types of fermentation?