Section Objectives:

1

• Section Objectives
• Compare and contrast cellular respiration and
  fermentation.
• Explain how cells obtain energy from cellular
  respiration.

2
Cellular Respiration

• The process by which mitochondria break down food
  molecules to produce ATP
• There are three stages of cellular respiration
  glycolysis, the citric acid cycle, and the
  electron transport chain.

High-energy electrons carried by NADH
ELECTRONTRANSPORT CHAIN
citric acid cycle,
GLYCOLYSIS
Cytoplasmicfluid
Mitochondrion
3
Cellular Respiration

• The first stage, glycolysis, is anaerobicno
  oxygen is required.
• The last two stages are aerobic and require
  oxygen to be completed.
• SUMMARY EQUATION

4
Glycolysis

• a series of chemical reactions in the cytoplasm
  of a cell that break down glucose, a six-carbon
  compound, into two molecules of pyruvic acid, a
  three-carbon compound
• produces only two ATP molecules for each glucose
  molecule broken down. (4-22)
• 2 molecules of NADH are formed

4ATP
2ATP
2ADP
4ADP 4P
Glucose
2 Pyruvic acid
2NAD
2NADH 2H
5
TransitionPhase.

• Before citric acid cycle and electron transport
  chain can begin, pyruvic acid undergoes a series
  of reactions in which it gives off a molecule of
  CO2 and combines with a molecule called coenzyme
  A to form acetyl-CoA.

Acetyl CoA(acetyl coenzyme A)
Pyruvicacid
CO2
6
The citric acid cycle

• also called the Krebs cycle, is a series of
  chemical reactions in that the molecule used in
  the first reaction is also one of the end
  products.
• For every turn of the cycle, one molecule of ATP
  and two molecules of carbon dioxide, 3 NADH, 1
  FADH2 are produced.
• Occurs in mitochondria

CO2
7
The electron transport chain

• In the electron transport chain, the carrier
  molecules NADH and FADH2 gives up electrons that
  pass through a series of reactions. Oxygen is
  the final electron acceptor
• the electron transport chain adds 32 ATP
  molecules to the four already produced

8
Fermentation

• During heavy exercise, when your cells are
  without oxygen for a short period of time, an
  anaerobic process called fermentation follows
  glycolysis and provides a means to continue
  producing ATP until oxygen is available again.
• 2 types 1. lactic acid
• 2. alcohol

9
Lactic acid fermentation

• Glucose-gtpyruvic acid -gt 2
  lactic acid
• 2ATP
• GLYCOLYSIS
  FERMENTATION
• used to make cheese and yogurt
• in humans during strenuous exercise
• not enough oxygen from blood oxygen debt
• lactic acid accumulates in muscle leads to
  fatigue and pain
• Will be converted back to pyruvic acid in liver

10
Alcoholic fermentation

• glucose -gt pyruvic acid-gt 2 ethyl alcohol
  2 CO2
• 2ATP
• GLYCOLYSIS
  FERMENTATION

• used by yeast cells and some bacteria to produce
  CO2 and ethyl alcohol