Unit C: Cellular Respiration

Unit C: Cellular Respiration

1. Cellular Respiration: how plants and animals generate energy from stored glucose

   • Glucose is stored as cellulose and starch in plants and it is stored as glycogen in animals. There are 2 types of CR: -Aerobic -Anaerobic
   • Anaerobic CR = NO OXYGEN
     • ALL organisms perform anaerobic cellular respiration - no special organelle is required.
     • Step 1: Glycolysis
       • Remember that this only yields 2 ATP in total
     • Step 2: Fermentation
       • Alcoholic Fermentation
         • 1) Water is added to pyruvate and a CO2 is expelled which creates a 2 carbon compound (Acetaldehyde) 2) NADH loses its electrons and becomes NAD+ as it reduces acetaldehyde into ethanol
         • Used in Brewing, Wine Making, and Baking
           • Also used in making Soy Sauce, Chocolate, Saki, Vinegar, and Biofuel
       • Lactic Acid Fermentation
         • 1) Pyruvate from glycolysis is reduced into lactic acid by NADH as it is oxidized into NAD+
         • Accounts for Sore muscles, Rigor Mortis, Yogurt & Sauerkraut
       • *remember that there are 2 pyruvates, so these rxns occur twice!
     • *The goal is to get the NAD+ back in order to keep performing glycolysis
   • Aerobic CR = OXYGEN
     • Organisms must have mitochondria in order to perform aerobic cellular respiration
     • Step 1: Glycolysis
       • 1) A glucose molecule is split into 2 PGAL molecules by the oxidation of 2 ATP (Energy investment) 2) NAD+ and ADP are reuced into NADH and ATP as they take electrons from the PGAL and become Pyruvate *this happens twice so a total of 2 NADH are produced & 4 ATP (2 ADP per PGAL)
       • *in cytoplasm
       • Energy input & payoff
         • Results in 2 ATP, 2NADH and 2 Pyruvates
       • not very efficient
         • - You only get 2 ATP from it
     • Step 2: Pyruvate Oxidation
       • 1) Pyruvate moves into the mitochondrial matrix and 1 carbon (CO2) is removed 2) NAD+ is reduced into NADH and an intermediate acetic acid is the result 3) Coenzyme A attaches to the acetic acid which forms Acetyl CoA
       • *in the mitochondria
       • Results in 2 NADH and 2 Acetyl CoA
       • *Happens twice b/c there were 2 Pyruvates made in glycolysis
     • Step 3: Kreb's Cycle
       • *in the matrix
       • *happens twice because 2 acetyl CoA's were made
       • Results in 6 NADH, 2ATP and 2 FADH2 & releases 4 CO2
     • Step 4: ETC & Chemiosmosis
       • 1) NADH and FADH2 enter the electron transport system in the inner mitochondrial membrane 2) They drop off their electrons & as they are transferred, an H+ is transported into the intermembrane space (this causes a very high concentration of protons) 3) The electrons are transpired to oxygen and join with a proton to produce water 4) The protons in the intermembrane space down their concentration gradient through ATP Synthase and facilitate the creation of ATP *The NADH that was made in glycolysis has to be converted into FADH2 in order for it to go through the mitochondrial membranes
       • occurs in the mitochondria
       • *where the most ATP is directly created
       • NADH = 3e- --> 3 ATP FADH2 = 2e- --> 2 ATP
       • Oxygen = terminal electron acceptor
       • Results in 24ATP
   • Electron carriers involved = NADH and FADH2
     • NADH is oxidized into NAD+ FADH2 is oxidized into FAD+
   • 36% Efficient
     • Only 36% of the energy in glucose is converted into ATP - the rest is lost as heat (this is used by warm-blooded organisms to stay warm)

2. ATP is used for many things

   • MOTION
   • TRANSPORTING IONS & MOLECULES
   • BUILDING MOLECULES
   • CONTROLLING RXNS
   • BIOLUMINESCENCE

3. Mitochondria are involved in anaerobic CR

   • -Double layered organelle that produces lots of ATP
   • Mitochondrial Matrix: protein rich liquid filling the inside of the organelle
     • *Pyruvate oxidation, the Kreb's Cycle, and Electron Transport and Chemiosmosis occur here
   • Intermembrane Space: fluid filled space between inner & outer membranes

4. Poisons & Supplements

   • Creatine Phosphate
     • = source of phosphate *more phosphate = more ATP? = harder workout session
   • Carbon Monoxide
     • -Binds to RBCs to prevents O2 transport which means there is no terminal electron acceptor -CR stops = death
   • Cyanide & Hydrogen Sulfide
     • Prevent electron transfer in the ETS -body can't survive off of 2 ATP from glycolysis so you die

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