Getting energy to make ATP

Process of breaking down food (glucose) to get energy. b/c food is not the direct source of energy, it has to be broken down by cells Happens in the mitochondria. C 6 H 12 O O 2  6CO 2 + 6H 2 O Basically the opposite of photosynthesis

Occurs 2 Ways: 1.Anaerobic w/o oxygen Has 1 stage: Glycolysis 2.Aerobic with oxygen has 3 stages– Glycolysis Krebs (citric acid) cycle Electron transport chain Glycolysis works the same way in both!!!

In two parts of the cell: Glycolysis occurs in the cytoplasm (Anaerobic) Krebs cycle & Electron transport chain takes place in the mitochondria (Aerobic) mitochondrion animal cell

Glycolysis must happen before cellular respiration can take place. –anaerobic process (does not require oxygen) –takes place in cytoplasm –splits glucose into two three-carbon molecules called pyruvate –produces 2 ATP molecules –Requires input of energy, but gets a good return *Like putting money into an account in order to gain interest *2 ATP in, 4 ATP out = 2 ATP net gain - Fast energy production, but not long STEP 1 a Pyruvate

Glycolysis Krebs

The Krebs cycle transfers energy to an electron transport chain. takes place in mitochondrial matrix breaks down pyruvate from 1a step glycolysis –makes 2 ATP –releases carbon dioxide –transfers energy-carrying molecules to next step (Electron transport chain) –Energy-carrying molecules called NADH & FADH 2 –they specifically carry electrons 6H O 2 6CO 2 6O 2 mitochondrion matrix (area enclosed by inner membrane) inner membrane ATP energy energy from glycolysis and Krebs Cycle Step 1b (requires Oxygen input after glycolysis) Electrons transferred via NADH

6H O 2 6CO 2 6O 2 mitochondrion matrix (area enclosed by inner membrane) inner membrane ATP energy energy from glycolysis and The electron transport chain produces 34 ATP. ( this is the 3 rd & last step!) –An ETC is made of proteins & needs energy-carrying molecules from the Krebs cycle & glycolysis –oxygen is also needed –takes place in inner membrane of mitochondria –34 ATP molecules are made –Water & heat are given off as wastes Electron Transport Electrons transferred via NADH

38 ATP 2 from Glycolysis 2 from the Krebs (Citric Acid) Cycle 34 from the Electron Transport Chain. Without oxygen (Anaerobic respiration) you only get 2 because O 2 is needed for the last two stages.

The equation for the overall process is: C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O The reactants in photosynthesis are the same as the products of cellular respiration.

6H 2 O 6CO 2 6O 2 mitochondrion matrix (area enclosed by inner membrane) inner membrane ATP Energy carrying Compounds (NADH, FADH 2 ) and Kreb’s cycle Glycolysis Electron Transport Chain ATP Energy carrying Compounds (NADH)