Cellular Respiration Why we breathe and how food

Cellular Respiration: Why we breathe and how food becomes ENERGY Chapter 9 http: //www. youtube. com/watch? v=Oi. Hw. Ed 2 B 3 o 0

How much energy is in food? A lot! Carbs and fats have more. 1 gram of glucose releases 3811 calories. Cells have to GRADUALLY release the energy from foods, like gas in your car.

9 – 1 Cellular Respiration Takes glucose (big molecule) and breaks it down, in the presence of oxygen (aerobic), to ATP. Know this equation: 6 0 + C H O = 6 CO 2 + 6 H O + energy(ATP) 2 6 12 It’s the opposite of photosynthesis! 6 2

This happens in 3 steps: #1 Glycolysis (glucose splitting) happens in the cytoplasm (gel like filler) of your cells. #2 Krebs Cycle #3 Electron Transport Chain– both in the mitochondria (remember the power station)?

Glycolysis: The 6 Carbon glucose is split in to two equal parts. So how many carbons are in each? These are now pyruvic acid.

Krebs Cycle If oxygen is present – pyruvic acid goes into the mitochondria. Here the 3 C is broken down and CO 2 comes off. 2 ATP are created and electron carriers NAD and FAD are loaded with Hydrogen ions to become NADH and FADH.

Electron Transport Chain http: //www. youtube. com/watch? v=_Pgjsf. Y 71 AM Here the electrons from the H move through proteins in the inner membrane while pumping the protons out into the space between the inner and outer membrane. This creates a concentration gradient where H+ are high outside and low inside. They will diffuse through a big enzyme (ATP Synthase) which powers the enzyme to add a phosphate group back to ADP to recreate ATP – Energy for you!!

End result: Our cells have usable energy in the form of ATP. We breathe out the CO 2 that is created as a waste product – from our lungs, and some water is formed in our cells. You have to breathe O 2 for this to happen or no ETC and you die from lack of ATP.

Fermentation: Releases energy from food by producing ATP when no oxygen is present (anaerobic). So what can live if no oxygen is present?

2 Types of Fermentation: 1) Alcoholic – alcohol and CO is formed from pyruvate. Ex: yeast making dough rise, fermented grapes make wine. Humans can’t do this. 2

2) Lactic Acid Fermentation Lactic acid is formed in your muscles during rapid exercise when the body can’t supply enough O 2 to the tissues. You feel sore the next day because of this!

Bromothymol Blue Indicator: Shows when CO 2 (an acid) is being produced from respiration by changing color.