BIOLOGY 414 NOTES Name:________________________MS. VITALE / MS. MENDENHALL

CHAPTER 9: CELLULAR RESPIRATIONThe Cellular Basis of Life

How do organisms obtain energy?

Questions you will be able to answer by the end of the chapter:1. Where do organisms get energy?2. What is cellular respiration?3. What is the relationship between photosynthesis and cellular respiration?4. What happens during the process of glycolysis?5. What happens during the Krebs cycle?6. How does the electron transport chain use high-energy electrons from glycolysis and

the Krebs cycle? 7. How much ATP does cellular respiration generate? 8. How do organisms generate energy when oxygen is not available?9. How does the body produce ATP during different stages of exercise?

1. Where do organisms get energy?

Organisms get the energy they need from “food” .

Where do we get the energy we need? Where do plants get the energy they need?- carbohydrates, fats, proteins - stored sugars

Do we release all the energy at once? No - we need a “controlled release” of energy -

release it slowly - otherwise most energy would be lost as heat and light (example: campfire with lighter fluid vs. without)

How do we measure the energy in the food we eat? calories (a unit like cm for distance)

calorie = the amount of energy needed to raise the temperature of 1 gram of water 1oC1000 calories = 1 kilocalorie = 1 Calorie

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2. What is cellular respiration?

Cellular respiration: the process that releases energy from food when oxygen is present

(“respiration” = “breathing” (exchange of gases - oxygen and carbon dioxide))

There are 3 stages:

1. Glycolysis - occurs in the cytoplasm- produce 2 ATP + NADH2. Krebs Cycle - occurs in the mitochondria (the “powerhouse” of the cell)- produce 2 ATP + NADH + FADH2

3. Electron Transport Chain (ETC) - occurs in the mitochondria- produce 32 ATP

Glucose (C6H12O6) is broken down through a series of reactions - when chemical bonds are broken energy is released - this energy is captured in a form cells can use (ATP)

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3. What is the relationship between photosynthesis and cellular respiration?

Cellular respiration and photosynthesis are REVERSE processes.

Equation for photosynthesis:

Carbon Dioxide + Water + Sunlight → Glucose + Oxygen

CO2 + H2O + Sunlight → C6H12O6 + O2

Equation for cellular respiration:

Glucose + Oxygen → Carbon Dioxide + Water + ENERGY

C6H12O6 + O2 → CO2 + H2O + 36 ATP

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4. What happens during the process of glycolysis?

Stage 1: Glycolysis

Location: cytoplasm

Inputs: glucose Outputs: pyruvic acid (pyruvate) + 2 ATP + NADH (NADH + FADH2 are high-energy molecules like NADPH in photosynthesis - they store energy but must be “exchanged” for ATP later in cellular respiration)

Oxygen needed? no

5. What happens during the Krebs cycle?

Stage 2: Krebs Cycle

Location: mitochondria (matrix)

Inputs: pyruvate + oxygen Outputs: carbon dioxide + 2 ATP + NADH + FADH2

(this is where the NADH + FADH2 produced earlier are “exchanged” for ATP)

Oxygen needed? yes

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6. How does the electron transport chain use high-energy electrons from glycolysis and the Krebs cycle?

Stage 3: Electron Transport Chain

Location: mitochondria (inner membrane)

Inputs: oxygen + NADH + FADH2 Outputs: water + 32 ATP

Oxygen needed? yes

7. How much ATP does cellular respiration generate?

Glycolysis: 2 ATP

Krebs cycle: 2 ATP

Electron Transport: 32 ATP_______________________

Total: 36 ATP

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8. How do organisms generate energy when oxygen is not available?

In the absence of oxygen, fermentation releases energy from food molecules by making ATP - but it is not nearly as efficient (2 ATP vs. 36 ATP)

1. Alcohol Fermentation

Location: yeast (microscopic fungi)

Inputs: pyruvic acid + NADH Outputs: alcohol + carbon dioxide + NAD+

pyruvic acid (3 carbon) + NADH → alcohol (2 carbon) + carbon dioxide + NAD+

Why?generate ATP without oxygen (an anaerobic environment) and recycle NADH to NAD+

2. Lactic Acid Fermentation

Location: bacteria (cheese/yogurt) + muscle cells

Inputs: pyruvic acid + NADH Outputs: lactic acid + NAD+

pyruvic acid (3 carbon) + NADH → lactic acid (3 carbon) + NAD+

Why?generate ATP without oxygen (an anaerobic environment) and recycle NADH to NAD+

What happened in the ball squeezing lab? Why did your arm muscles burn?

9. How does the body produce ATP during different stages of exercise?

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Quick bursts (sprint): first 90 seconds

first: use small amount of ATP stored in muscle cells (50 meters)second: lactic acid fermentation (does not require oxygen) (200 meters)

Long-Term (marathon):

cellular respiration (requires oxygen)

Extra Resources:● Video: ATP & Respiration: Crash Course Biology #7 http://www.youtube.com/watch?

v=00jbG_cfGuQ● Podcast: Cellular Respiration (Bozeman Science) http://www.youtube.com/watch?

v=Gh2P5CmCC0M● Notes: Cellular Respiration (Biology Junction)

http://www.biologyjunction.com/cell_respiration_bi.htm

Recursos en Español (de respiración celular):● Resumen: http://es.wikipedia.org/wiki/Respiración_celular● Podcast: http://www.investiciencias.com/index.php/articulos/respiracion/respiracion● Podcast: http://www.youtube.com/watch?v=m1Gk78i4Sjc

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