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

1. Humans use fats, proteins, and carbohydrates as sources of energy or food.

2. When you eat food energy is released

3. Calories can measure how much energy is in the food you eat

4. 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

1. 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

2. Food is the material for the mitochondria in the cells in the body & to produce energy.

Mitochondria

Animal Cell

Plant Cell

Animal

Plant

Discuss w/ Partner

1. What chemical in organisms is used as a source of energy?

* Hint- it has three letters

Answer

ATP

III. GLYCOLYSIS

1. Glycolysis– the process that breaks one molecule of glucose (C6H12O6) a 6- carbon compound in half into pyruvic acid, a 3- carbon compound.

2. Glycolysis happens in the cytoplasm of the cell

3. Glycolysis can take place w/ or w/o oxygen The glycolysis pathway

4. During glycolysis:NAD+ becomes NADHPyruvic Acid (a 3-carbon molecule) is formed

5. Glycolysis results in : • 2 ATP molecules

• 2 NADH molecule• 2 pyruvic acid

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

6. ATP Production • At the beginning of glycolysis, the cell uses up 2 molecules of ATP to start glycolysis

2 ADP 4 ADP 4 ATP

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?

7. Advantages of glycolysis:

a) No oxygen is needed

b) 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

1. If no oxygen is present after glycolysis fermentation takes place

2. Fermentation- the release of energy from food without oxygen being present

3. Fermentation is an anaerobic process

4. Anaerobic- Oxygen is not needed (w/o oxygen)

5. There are two types of fermentation:a) Alcoholic

b) Lactic Acid

6. 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+

7. 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+

Discuss w/ Partner:

Does Fermentation take place with O2?

Answer

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