BIOLOGY 414 NOTES
MS. VITALE / MS. MENDENHALL
Name:________________________
CHAPTER 9: CELLULAR RESPIRATION
The 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 1 oC
1000 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 + NADH
2. 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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