Download Cellular respiration

I. Cellular respiration
• The process of breaking down food to make
energy.
• Occurs in the mitochondria of the cell.
• A process called glycolysis must take place first
before it can happen.
A. Glycolysis
• The process of breaking down food, usually
glucose.
• Occurs in the cytoplasm of cells.
• Doesn’t require oxygen.
• The cell must borrow 2 ATP to start the process.
• Creates a product called pyruvic acid.
• The end product, pyruvic acid, will enter cellular
respiration if oxygen is available in the cell.
• 4 ATP is made but because 2 was borrowed, 2
must be paid back. Net gain is only 2ATP.
B. Cellular respiration – Kreb Cycle
• If oxygen is available in the cell, pyruvic acid will
enter the mitochondria for aerobic cellular
respiration.
• The first step is the Kreb cycle.
• The Kreb cycle produces some ATP but also
produces carbon dioxide. This carbon dioxide is a
waste product of the Kreb cycle that we exhale.
• The products NADH and FADH2 will then enter
the electron transport chain.
C. Cellular Respiration – electron transport chain (ETC)
• When the kreb cycle is done, the 2nd step of cellular
respiration occurs. The electron transport chain.
• In this 2nd step, the most number of ATP is produced.
About 36 molecules of ATP is made. More or less can
be made depending on the type of cell. A fat cell will
make less ATP than a muscle cell.
• In addition to making ATP water is also produced.
• NADH and FADH2 drops of the “hydrogen” becoming
NAD and FAD to pick up more “hydrogen”.
II. What if there’s no oxygen?
• After glycolysis, if oxygen is not available in the cell
pyruvic acid will enter an alternate pathway called
Anaerobic Fermentation.
• There are two types:
– Alcoholic fermentation (how beer, wine and cider is made).
– Lactic acid fermentation (done by animals & yeasts)
• the cramping you feel in your muscle after heavy heavy exercise…
“charlie horse”
• How sour foods such as sauerkraut, dry sausages, kimchi, yogurt
and other pickled foods
• Fermentation is important because it produces NAD+
which is needed to keep glycolysis running until oxygen
becomes available.