Ch. 9 Cellular Respiration This football player uses cellular respiration to get energy during football games

9-1 Chemical Pathways An overview of glycolysis, cell respiration, & Fermentation

I. Chemical energy and food

When you eat food energy is released Humans use fats, proteins, and carbohydrates as sources of energy or food. When you eat food energy is released Calories can measure how much energy is in the food you eat Calorie- the amt. of energy needed to raise the temp. of 1 gram of water 1oC The fruit this lady eats will be digested & the energy from the food will be released into her body.

II. Overview of cellular Respiration

During cellular respiration energy is released from food by breaking it down in the presence of oxygen (O2) The equation for cellular respiration is: 6O2 + C6H12O6 → 6CO2 + 6H2O + Energy oxygen + glucose → carbon dioxide + water + energy

Food is the material for the mitochondria in the cells in the body & to produce energy. Animal Cell Animal Mitochondria Plant Plant Cell

Discuss w/ Partner What chemical in organisms is used as a source of energy? * Hint- it has three letters

Answer ATP

III. Glycolysis

Glycolysis happens in the cytoplasm of the cell Glycolysis– the process that breaks one molecule of glucose (C6H12O6) a 6- carbon compound in half into pyruvic acid, a 3- carbon compound. Glycolysis happens in the cytoplasm of the cell Glycolysis can take place w/ or w/o oxygen The glycolysis pathway

Glycolysis results in : 2 NADH molecule 2 pyruvic acid During glycolysis: NAD+ becomes NADH Pyruvic Acid (a 3-carbon molecule) is formed Glycolysis results in : 2 ATP molecules 2 NADH molecule 2 pyruvic acid

What kind of molecule is NAD+? *Hint: think of photosynthesis! Discuss w/ Partner: What kind of molecule is NAD+? *Hint: think of photosynthesis!

Answer! An electron Carrier! It carries hydrogen electrons like NADP+ carries hydrogen electrons during photosynthesis

ATP Production At the beginning of glycolysis, the cell uses up 2 molecules of ATP to start glycolysis 4 ADP 4 ATP 2 ADP 2

Show How Cells Get Energy Video

Discuss w/ Partner: Look at Figure 9-2 on page 222 and answer the following questions. 1. Where does the glucose used in respiration come from? 2. How do you know that this series of reactions occurs in the presence of oxygen? 3. What does glycolysis supply to the Krebs Cycle and to the electron transport chain?

Advantages of glycolysis: No oxygen is needed Takes place extremely fast thousands of ATP molecules can be produced in less than one second. Every molecule of glucose in the bread this little girl eats will turn into 2 ATP molecule and 2 pyruvic acid molecules

IV. Fermentation

If no oxygen is present after glycolysis fermentation takes place Fermentation- the release of energy from food without oxygen being present Fermentation is an anaerobic process Anaerobic- Oxygen is not needed (w/o oxygen) There are two types of fermentation: Alcoholic Lactic Acid

Alcoholic Fermentation Pyruvic acid from glycolysis forms ethyl alcohol and carbon dioxide as waste Used by yeasts and other organisms The equation for alcoholic fermentation after glycolysis is: pyruvic acid + NADH → alcohol + CO2 + NAD+

Takes place in muscle cells during rapid exercise due to lack of O2 Lactic Acid Fermentation- forms 2 lactic acid molecules from 2 pyruvic acid molecules; results in the production of ATP Regenerates NAD+ so glycolysis can continue Takes place in muscle cells during rapid exercise due to lack of O2 The result: the muscle cells are able to produce ATP

Some unicellular organisms produce lactic acid as a waste product, which allows humans to make cheese, yogurt, etc. The equation for lactic acid fermentation after glycolysis is: pyruvic acid + NADH → lactic acid + NAD+

Does Fermentation take place with O2? Discuss w/ Partner: Does Fermentation take place with O2?

Fermentation takes place after glyco lysis if there is no oxygen! Answer NO Fermentation takes place after glyco lysis if there is no oxygen!