Harvesting Energy: Glycolysis Fermentation Cellular Respiration

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Harvesting Energy Glycolysis Fermentation
Cellular Respiration
Chapter 7
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Introduction and Vocabulary

• Metabolism
• Cells can metabolize a variety of organic
  compounds,but we will concentrate on the
  metabolism of glucose because it is the most
  common form of metabolism
• NAD Coenzyme used in reactons, can accept
  electrons and becomes NADH
• Aerobic with oxygen
• Anaerobic without oxygen

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Different Stages of Glucose Metabolism

• 1. Glycolysis
• Does not require oxygen
• Occurs in Cytoplasm of the cell
• Produces pyruvate, 2 ATP, and 2 NADH

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Different Stages of Glucose Metabolism

• 2. Fermentation
• Without oxygen
• Anaerobic
• Pyruvate is converted into lactate or ethanol and
  CO2
• No ATP Produced
• Occurs in cytoplasm of cells

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Different Stages of Glucose Metabolism

• 3. Cellular Respiration Includes glycolysis,
  Krebs cycle, and electron transport chain
• Presence of oxygen
• Aerobic
• Pyruvate converted into CO2 and H2O, and 36 to 38
  ATP are produced
• Occurs in the mitochondria of cells

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How is The Energy of Glucose Captured During
Glycolysis?

• Glycolysis means to break apart
• Glucose is broken down with or without oxygen in
  the cytoplasm into pyruvate
• One Glucose is cleaved into two pyruvate
• Produces little energy
• Two ATP and Two NADH produced

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Glycolysis Has Two Steps

• a). Glucose Activation
• b). Energy Harvesting Stage

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a).Glucose Activation

• Before glucose is broken down, it is activated.
  This takes energy (2 ATP)
• This reaction cost 2 ATP molecules

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b).Energy Harvesting Steps

• 1 Glucose splits into 2 G3P (3 carbon molecule)
• G3P molecule converts to 2 pyruvate
• 2 ATP are generated for each G3P to total 4 ATP,
  but you only get 2 ATP since you used 2 ATP to
  activate glucose
• 2 NADH produced, NADH is an electron carrier,
  NAD is an electron acceptor

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Glycolysis
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• Note if oxygen is available, cellular
  respiration will occur in the mitochondria of the
  cell, but there is no available oxygen,
  fermentation will take place in the cytoplasm.
• Absence of oxygen
• Production of ethanol or lactate
• This is called fermentation
• No ATP produced
• Occurs in cytoplasm

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Two Types of Fermentation

• a). Conversion of pyruvate into lactate (lactic
  acid)
• b).Conversion of pyruvate into Co2 Ethanol

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a). Fermentation to Lactate (Muscles)

• Occurs in cytoplasm of muscles after vigorous
  exercise, sprinting fast, anaerobic activity
• Build up of Lactic acid
• Not enough oxygen to lungs, blood, and muscles to
  allow for cellular respiration
• Glycolysis does not stop
• Without oxygen, muscle cells ferment pyruvate to
  lactate or lactic acid
• If you stop the anaerobic exercise or slow down,
  and as you breath, oxygen becomes available.

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Fermentation Continued

• Lactate converts back to pyruvate, this happens
  in the liver
• Pyruvate then in presence of oxygen can be broken
  down into CO2 H2O by cellular respiration

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2 ADP 2
Glycolysis
2 NAD?
2 NAD?
Glucose
2 Pyruvic acid
2 H?
2 Lactic acid
(a) Lactic acid fermentation
Figure 6.15a
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b). Fermentation to Alcohol( microorganisms)

• Many microorganisms use this process
• Anaerobic conditions
• Produces ethanol and CO2 from pyruvate
• Yeast (microorganism), fermented fruits and
  grains into alcoholic beverages
• Champaign is bottled while the yeast are still
  alive so it traps both ethanol and CO2 and gives
  the cork a pop when opened
• Bakers yeast produces CO2, that is what makes the
  bread rise, the ethanol evaporates while cooking
  in the over

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• THE END OF HARVESTING ENERGY
• Part 1
• Glycolysis and Fermentation