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2 Cellular Respiration Harvesting Chemical Energy ATP

3 Energy needs of life Animals are energy consumers –What do we need energy for? Synthesis – building molecules and compounds in the body Reproduction Active transport – remember from last week? Movement Temperature control – oh yea…homeostasis

4 Where do we get energy? Energy is stored in organic molecules –carbohydrates, fats, proteins – oh yea, we learned about these things three weeks ago! Animals eat these organic molecules – food!!! Food is digested, providing –fuels for energy (ATP) –raw materials for building more molecules –carbohydrates, fats, proteins, nucleic acids

5 ATP What is energy in biology? Whoa! Hot stuff!

6 How do we harvest (get) energy stored in food? Cellular respiration –Process of breaking down food to produce ATP Occurs in mitochondria – remember these from two weeks ago? using oxygen –formula identified below shows glucose, but could be other sugars, fats or proteins glucose + oxygen  carbon + water + energy dioxide C 6 H 12 O 6 6O 2 6CO 2 6H 2 O36ATP  + +++ heat

7 CO 2 + H 2 O + heat Fuel (firewood) O2O2 We “burn fuels” to make energy 1) Combustion – (when you burn firewood, a familiar example) making heat energy by burning fuels in one step ATP CO 2 + H 2 O + ATP (+ heat) 2) Respiration – when you “burn” food making ATP energy (& some heat) by burning fuels in many small steps food (carbohydrates) O2O2

8 How do we use ATP for work in our bodies? A working muscle recycles over 10 million ATPs per second Whoa! Pass me the glucose & oxygen! We can’t store ATP  too unstable  only used in cell that produces it  only short term energy storage  carbohydrates & fats are long term energy storage

9 What do we need to make energy? The “Furnace” –mitochondria Fuel –food carbohydrates, fats, proteins The Helpers –oxygen “aerobic” –enzymes O2O2 food ATP Make ATP! Make ATP! All I do all day… And no one even notices!

10 How do we make ATP from food? ATP ADP + P work 1.The molecule ADP (adenosine diphosphate (“di” means two) joins with another phosphate (P) molecule to form adenosine triphosphate 2.ADP + P  ATP 3.The ATP is then used for cellular work and is broken down again to ADP and P 4.When energy is made available from food, the ADP and P will join together again to produce ATP The cycle repeats, just like a rechargeable battery Follow the numbered steps that correspond with the graphic 1, 4 2 3

11 What if oxygen is missing? Cells are unable to complete aerobic cellular respiration, and anaerobic respiration occurs –Alcohol fermentation can occur Yeast are the organisms that do this –glucose  (breaks down into) ATP + CO 2 + alcohol –beer, wine, bread made this way –Lactic acid fermentation – this is what happens in our muscles! (Ever feel or hear of a “runner’s or swimmer’s burn”? Occurs in bacteria, animals –glucose  (breaks down into) ATP + lactic acid –animals feel muscle fatigue Yogurt made this way O2O2 These only make a little bit of ATP!

12 Resources www.bio.kimunity.com Miller, Ken and Joe Levine. Prentice hall Biology. Pearson Education Inc. New Jersey, 2005.