Transcript CH- 9 Cellular Respiration

You eat food to get
energy…..how does this
work? By a process called……
Plants make their food, so to
get energy from the food
they produce they also use a
process called …..
1st step – Glycolysis (using Latin P&S,
glycolysis means – loosening of glucose)
 The process in which one molecule of
glucose is broken in half, producing
two molecules of pyruvic acid.
 Takes place in the cytoplasm
 Creates 2 ATP
2nd step – the Krebs Cycle
 Pyruvic acid is broken down in to
carbon dioxide in a series of energy
extracting reactions.
 Creates NADH and FADH2 (energy
carriers, full batteries)
 Takes place in the mitochondria
 Creates 2 ATP
3rd step – Electron Transport Chain
 Uses the energy stored in NADH and
FADH2 to create ATP
 Takes place in the mitochondria
 Creates 32 ATP
ATP
Big Picture
 Glycolysis + the Krebs Cycle + Electron Transport Chain
= CELLULAR RESPIRATION
 6O2 + C6H12O6  6CO2 + 6H20 + energy
o This equation is the OPPOSITE of
photosynthesis
Cellular Respiration only works if
you have oxygen (which we
breathe in), but sometimes your
body can’t get oxygen quickly
enough to do cellular respiration
… what happens then?
1st step – Glycolysis
 Glycolysis does NOT require oxygen, so
the first step is the same.
2nd step – Alcoholic Fermentation
 Yeasts and a few other microorganisms
take the two molecules of pyruvic acid
produced in glycolysis and convert it to
alcohol, carbon dioxide and NAD+
 Pyruvic acid + NADH  alcohol + CO2 + NAD+
 Alcoholic fermentation of yeast is what causes bread
to rise. When yeast in the dough runs out of oxygen
it begins producing carbon dioxide which forms the
air spaces you see in a slice of bread. The small
amount of alcohol produced in the dough evaporates.
OR 2nd step – Lactic Acid Fermentation
 In many cells, the pyruvic acid from glycolysis
is converted to lactic acid.
 Pyruvic acid + NADH  Lactic Acid + NAD+
 When you exercise vigorously by running, swimming or
riding a bike, your large muscles quickly run out of
enough oxygen to do cellular respiration. Instead
your muscle cells start doing lactic acid fermentation
to make ATP (energy). The build up of lactic acid
causes a painful burning sensation.
 The only way to get rid of this lactic acid is through a
process that requires oxygen. This is why you
breathe harder after physical activity.