CELL RESPIRATION

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CELL RESPIRATION

• Stage 4 - Electron Transport Chain (ETC)

This lesson meets the following DoE Specific
Curriculum Outcomes for Biology 11 314-2 and
314-9.
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ELECTRON TRANSPORT CHAIN

• The electron transport chain is located on the
  inner membrane of the mitochondrion.
• It consists of several electron carriers which
  accept electrons from NADH and FADH2 (from
  glycolysis and Krebs cycle).
• It requires O2!

3
ELECTRON TRANSPORT CHAIN

• Energized electrons from Glycolysis and Krebs
  cycle are carried to the electron transport chain
  via NADH and FADH2.
• Electrons are passed through a series of electron
  carriers which become reduced then oxidized as
  they accept then pass off the electrons.

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ELECTRON TRANSPORT CHAIN

• The free energy gained from the electrons as they
  pass from carrier to carrier is used to
  phosphorylize ADP to ATP .
• The electrons eventually unite with protons (H)
  and oxygen at the end of the ETC to form water..
• Oxidative phosphorylation!!

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ELECTRON TRANSPORT CHAIN

• If insufficient O2 is available in the cell, the
  ETC will not work!
• Cyanide inhibits cytochrome oxidase activity,
  preventing oxygen from acting as the final
  electron acceptor in the electron transport
  chain.
• This disruption virtually shuts down ATP
  production resulting in coma and death.

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METABOLIC PATHWAYS

• Although glucose is a major energy fuel for cell
  respiration, other carbohydrates (sugars) can
  also be used.
• Complex carbohydrates are broken down into simple
  sugars like glucose by the digestive system
  before being catabolised by glycolysis.

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METABOLIC PATHWAYS

• Other fuel sources include proteins, lipids
  (fats) or nucleic acids.
• Proteins are digested into amino acids.
• The amino groups are converted to ammonia (a
  waste product) and the remainder is converted to
  Pyruvate or Acetyl CoA and enters cell
  respiration.

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METABOLIC PATHWAYS

• Lipids are digested into glycerol and fatty
  acids.
• Glycerol in converted to glucose or PGAL and is
  then metabolized by cell respiration.
• Fatty acids are converted to Acetyl CoA.
• Nucleic acids are digested into nucleotides that
  are then converted to A CoA and NH4.

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METABOLIC PATHWAYS