1. Cellular Respiration ATP

2. Sunlight energy ECOSYSTEM Photosynthesis in chloroplasts Glucose Cellular respiration in mitochondria H2OH2O CO 2 O2O2  (for cellular work) ATP Heat energy

3.  Breathing and cellular respiration are closely related –Breathing is necessary for the intake of O 2 and getting rid of CO 2 –Cellular respiration uses O 2 to help harvest energy from glucose and produces CO 2 in the process

4. Breathing Cellular Respiration Muscle cells carrying out CO 2 + H 2 O + ATP Lungs Bloodstream CO 2 O2O2 O2O2 Glucose + O 2

5.  Cellular respiration is an exergonic process that transfers energy from the bonds in glucose to ATP –Cellular respiration produces 36 ATP molecules from each glucose molecule –Other foods (organic molecules) can be used as a source of energy as well

6. C 6 H 12 O 6 + 6O2O2 Glucose Oxygen 6 CO 2 Carbon dioxide + 6 H2OH2O Water + ATPs Energy

7.  The average adult human needs about 2,200 kcal of energy per day –A kilocalorie (kcal, 1000 cal) is the quantity of heat required to raise the temperature of 1 kilogram (kg) of water by 1 o C –This energy is used for body maintenance and for activities

9.  The energy necessary for life is contained in the chemical bonds in organic molecules  How do cells extract this energy?

10.  When the covalent bonds that hold glucose together are broken, electrons start getting transferred to other molecules and, finally, to oxygen –Remember, oxygen likes electrons—we saw that in the H 2 0 molecule

11.  How does energy get released from glucose?  You can burn it, but that might hurt!  We would catch on fire and maybe explode.  (Have you ever microwaved marshmallows?)

12.  Our other choice: Use cellular respiration for a controlled, stepwise explosion. –Energy is released in small amounts that can be captured by a biological system and stored in ATP ATP

13.  What is the bottom line in cellular respiration? –Glucose loses its hydrogen atoms (proton & electron) and is ultimately converted to CO 2 –At the same time, O 2 gains hydrogen atoms (proton & electron) and is converted to H 2 O –Loss of electrons is called oxidation –Gain of electrons is called reduction

14. A “reducing agent” becomes oxidized. An “oxidizing agent” becomes reduced.

15. C 6 H 12 O 6 + 6 O 2 Glucose Loss of hydrogen atoms (oxidation) 6 CO 2 + 6 H 2 O + Energy Gain of hydrogen atoms (reduction) (ATP) Oxidation & Reduction Together, its called a “Redox” equation

16.  Many enzymes are necessary to oxidize glucose –One enzyme removes hydrogen from an organic molecule: dehydrogenase –Dehydrogenase requires a coenzyme called NAD + (nicotinamide adenine dinucleotide) to shuttle electrons –NAD + can become reduced when it accepts electrons and oxidized when it gives them up –“NADH, H+” is the reduced form

17. 2 H + + 2 e – Oxidation Dehydrogenase Reduction NAD + + 2 H NADH + H+H+ (carries 2 electrons)

18.  There are other electron “carrier” molecules that function like NAD + (ex. FAD, NADP+) –They form a staircase where the electrons pass from one to the next down the staircase –These electron carriers collectively are called the electron transport chain, and as electrons are transported down the chain, ATP is generated

19. ATP NAD + NADH H+H+ H+H+ 2e – Electron transport chain Controlled release of energy for synthesis of ATP + O2O2 H2OH2O 1212