Transcript Chemical Pathways

Chemical Pathways
Food is your source of energy!
 Calorie-amount of energy needed to raise the temperature of
1 gram of water 1 degree Celsius
 1 kilocalorie is 1000 calories
 Kilocalories are actually on the food package but we call it
CALORIES
 Cells use calories from food to make ATP
 Cellular energy
 Break off the phosphate molecules and we release energy
 Form ADP
 ADP is made back into ATP through cell respiration
 Plants and animals carrying out cell respiration.
Cell Respiration Overview
 Release energy by breaking down glucose and other food
molecules with the help of oxygen
 Equation
 Oxygen + glucose= carbon dioxide + water+ ATP
 Take place in the mitochondria
 Two types of respiration:
 Anaerobic-does not use oxygen
 Aerobic-uses oxygen
Glycolysis
 Takes place in the
cytoplasm of the cell
 INPUTS: Glucose and 2
molecules of ATP
 OUTPUTS: 4 ATP (net
gain of 2) and pyruvic acid
 NADH holds electrons for
later use to create tons of
energy
 Called an electron carrier
Fermentation
 If oxygen is not present, fermentation takes place after
glycolysis
 Fermentation-releases ATP from food without the use of
oxygen
 Two main types
 Alcoholic fermentation-yeast form ethyl alcohol and carbon dioxide as
waste; cause bread dough to rise
 Lactic acid fermentation-lactic acid is produced
 Created when your muscles do not have enough oxygen to produce
ATP when exercising
o Buildup of lactic acid creates a painful burning sensation
 Unicellular organisms use to make food like yogurt, cheese, sour
cream, pickles, sauerkraut
Section 9.2 Kreb Cycle (citric acid
cycle)
 Pathway is aerobic-needs oxygen
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to function
Pyruvic acid from glycolysis
enters the mitochondria
Carbon is removed from this
acid to form carbon dioxide
Pyruvic acid will turn into acetyl
CoA
Acetyl CoA will turn into citric
acid
Citric acid goes through the
cycle to form ATP, carbon
dioxide, NADH and FADH2
(these two items hold high
energy electrons that will be
used in the next cycle)
Electron Transport Chain
 NADH and FADH2 is passed
to this stage in the membrane
of the mitochondria
 The electrons that are in
these two molecules are
passed along the carrier
proteins in the membrane
 Water will form at the end of
this chain
 Kreb and electron transport
chain produce 36 ATP per
one molecule of glucose
We don’t always consume glucose
so how do we make ATP?
 Complex carbohydrates are broken down into glucose.
 Lipids and proteins can be broken down into molecules that
enter the Kreb cycle and electron transport chain
Energy and exercise
 Quick energy
 Enough ATP for a short time
 Rest of time ATP is produced by lactic acid fermentation
 After race, heavy breathing is used to increase oxygen to repay
the oxygen debt
 Long term energy
 For exercise that is 90 seconds or longer, body relies on cell
respiration
 Use stored energy in the form of glycogen
 Body will begin to break down other stored molecules like fat