The Krebs / Citric Acid Cycle and the Electron Transport Chain!! Aerobic Respiration!! The Krebs / Citric Acid Cycle and the Electron Transport Chain!!

Yeast! – Overview of Yeast Worksheet Which beaker has more ‘bubbles’?

What are the bubbles made of?

Yeast experiment; Which flour sample had sugar added to it? Both produce CO2, but one produced many more bubbles much more quickly. Aerobic respiration is much more efficient than anaerobic respiration (or fermentation) and produced CO2 much faster as well. Which dough had the sugar added?? Beaker B!!

Fermentation Occurs when O2 NOT present (anaerobic) Called Lactic Acid fermentation in muscle cells (makes muscles tired) Called Alcoholic fermentation in yeast (produces CO2 and ethanol; this is what gives beer, wine, etc., their alcohol content!)

Aerobic Respiration Intro Activity Follow instructions on the hand-out and complete the graph. DON’T get any of the solution in your mouth! Exhale into the straw at a normal breathing pace, even after 2 minutes of exercise (slow it down!).

Speaking like a scientist: Analyzing Data: How did exercise affect the time it took for the solution to change colour? E.x. “Based on the data, exercise (increased / decreased) the time it took for the bromothymol blue solution to change colour.” **WAIT before making your final conclusions! **

Respiration Overview: 2x 2x 34x

1) Where Does Cellular Respiration Take Place? Aerobic respiration takes place in the Mitochondria It takes place in two parts of the cell: Anaerobic respiration (Glycolysis + fermentation) occur in the Cytoplasm

2) Review of Mitochondria Structure Smooth outer Membrane Folded inner membrane Folds called Cristae Space inside cristae called the Matrix

3) When oxygen is available, Pyruvic Acid is transported into the mitochondria and converted to Acetyl-CoA. This molecule is then used as part of the next respiration phase, the Krebs Cycle; The Pyruvic Acid  Acetyl-CoA conversion also released 1 CO2 molecule !! Cytoplasm + Fermentation if no O2

4) History Lesson – The Krebs Cycle!! Discovered by Hans Krebs in 1937 He received the Nobel Prize in physiology or medicine in 1953 for his discovery Forced to leave Germany prior to WWII because he was Jewish

5-7) Krebs Cycle – Also called the Citric Acid Cycle During a single “turn” of the Krebs cycle an acetyl-CoA molecule is converted to a molecule of citric acid! The citric acid molecule’s bonds are broken and re-arranged, releasing ENERGY and TWO CO2 molecules! Enough energy is produced to make _______ ATP. 1

6) Krebs Cycle Summary Also during the Krebs Cycle, electrons are attached to NAD+ and FAD+, another electron-carrying molecule, forming NADH and FADH2 These molecules are then used in the E.T.C.!

7) How many turns? 7) Each glucose molecule allows for TWO turns of the Krebs cycle, and a total of: 6 CO2 and 2ATP are produced!! (Remember the 2 CO2 produced from the conversion of Pyruvic Acid to Acetyl-CoA!) ***Now you have enough information to write your 3-sentence conclusion from the lab before!!***

The Electron Transport Chain !! 1) The inner membrane of the mitochondria is lined with structures that remove the electrons and H+ from the electron transporting molecules: ____________ and _____________! NADH FADH2

The Electron Transport Chain !! 2) The H+ ions are forced out of the matrix and into the inter-membrane space (the space between the inner and outer membrane of the mitochondria – see text p. 259) H+ pumps move the H+ into the inter-membrane space by active transport.

The Electron Transport Chain !! 3) The H+ ions want to move from the inter-membrane space back into the matrix; to get back in they must travel through an enzyme, called _______________, that’s attached to the inner membrane. ATPsynthase

The Electron Transport Chain !! 3) The H+ ions want to move from the inter-membrane space back into the matrix; to get back in they must travel through an enzyme, called _______________, that’s attached to the inner membrane. ATPsynthase

The Electron Transport Chain !! 4) The movement of the H+ molecules through ATPsynthase makes it spin! With each rotation, a phosphate is attached to an ADP molecule, forming __________! ATP!

The Electron Transport Chain !! 5) Inside the mitochondrial matrix, these H+ ions (a.k.a. protons), O2 molecule and free-flowing electrons (e-) combine to form water. The formation of water is an_____________ reaction, meaning it produces energy! _____________ is so important for cellular respiration because it’s the final electron acceptor in the E.T.C.!! Without it, the E.T.C. wouldn’t function. exothermic O2

The Electron Transport Chain !! 6) This chain continues all along the inner mitochondrial membrane, with H+ moving in and out the whole way… and in total, from 1 glucose molecule _______ ATP are produced! (the multi-step chain has some sections that produce more or less ATP than others!) 32-34

Electron Transport Chain Summary 32-34 ATP Produced ~6 H2O Produced NAD+ and FAD+ are regenerated for use in the Krebs Cycle and glycolysis!!

Cytoplasm Pyruvic acid 2 ATP 32-34 Total ATP Output: 36-38 ATP!

**see next slide for clarification

CLARIFICATION!! -- There are two types of Lactic Acid Fermentation… Homolactic and Heterolactic Fermentation In Homolactic Acid Fermentation (like in humans), all of the pyruvic acid is converted to lactic acid, and no CO2 is produced. In heterolactic acid fermentation, some of the pyruvic acid isn’t fully converted to pyruvic acid, and CO2 is produced as a byproduct.

Ignore / cross out

Overall Equation for Cellular Respiration YIELDS C6H12O6 + 6O2 6CO2 + 6H20 + 34-36ATP

Images Reference: https://room114.wikispaces.com/Cellular+Respiration

Structure of ATP

Copyright Cmassengale The ADP-ATP Cycle ATP Synthetase ATP-ase Copyright Cmassengale