Ch. 9:

1
Ch. 9 Cellular Respiration

• 9.1 Chemical Pathways

2
Chemical Energy and Food

• There is quite a bit of energy contained in the
  food that we eat.
• The process of releasing the energy contained in
  the foods that we eat begins with a process
  called glycolysis.
• Glycolysis releases only a small amount of
  energy.
• If oxygen is present, glycolysis leads to two
  other pathways that release a great deal of
  energy.
• If oxygen is not present, however, glycolysis is
  followed by a different pathway.

3
Overview of Cellular Respiration

• In the presence of oxygen, glycolysis is followed
  by the Krebs cycle and the electron transport
  chain.
• In the absence of oxygen, glycolysis is followed
  by fermentation.
• Glycolysis, the Krebs cycle, and the ETC make up
  a process called cellular respiration.
• This process releases energy by breaking down
  glucose and other food molecules in the presence
  of oxygen.

4
Glycolysis

• Glycolysis is the process in which one molecule
  of glucose is broken in half, producing two
  molecules of pyruvic acid, C3H6O3.
• For glycolysis to begin, 2 ATPs must be borrowed
  and repayed at the end.
• The energy yield from glycolysis is small 2
  ATPs, but the process itself is quite fast.
• Glycolysis does not require oxygen, so energy can
  still be supplied when oxygen is not available.
• Because it does not require oxygen, it is called
  anaerobic.

5
Fermentation

• When oxygen is not present, glycolysis proceeds
  to fermentation.
• Fermentation releases energy from food by
  producing ATP in the absence of oxygen.
• Fermentation is anaerobic.
• There are two types of fermentation alcoholic
  fermentation and lactic acid fermentation.

6
Fermentation Anaerobic Respiration.
http//www.5min.com/Video/How-Fermentation-Works-8
3226972

• Alcoholic Fermentation
• Used by yeast and a few other microorganisms
• Produces ethyl alcohol and carbon dioxide as
  wastes.
• Pyruvic acid NADH ? alcohol CO2 NAD
• This process is used by the beer, wine, bread
  industries for the production of their products.

• Lactic Acid Fermentation
• Used by multicellular organisms and some
  unicellular organisms.
• Lactic acid is produced in your muscles during
  rapid exercise when the body cannot supply enough
  oxygen to the tissues.
• The buildup of lactic acid in your muscles will
  make them sore!!
• Prokaryotes are used in the production of a wide
  variety of foods and beverages such as cheese,
  yogurt, buttermilk, and sour cream.
• Pyruvic acid NADH ? lactic acid NAD