cellular respiration notes - mr. uchimerespiration notes •the transformation of chemical energy in...
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CELLULAR RESPIRATION
NOTES
• The transformation of chemical energy in food into chemical energy cells can use: ATP, adenosine triphosphate.
• These reactions proceed the same way in plants and animals. Process is called cellular respiration.
• Overall Reaction:• C6H12O6 + 6O2 → 6CO2 + 6H2O
• FLIP THE REACTANTS & PRODUCTS TO GET THE EQUATION FOR PHOTOSYNTHESIS!
Cellular Respiration Overview
Cellular Respiration Overview
• Breakdown of glucose begins in the cytoplasm.
• At this point life diverges into two forms and two pathways• Anaerobic cellular respiration (aka fermentation)
• Aerobic cellular respiration
STEPS OF CELLULAR RESPIRATION
1. Glycolysis• Series of reactions which break
the 6-carbon glucose molecule down into two 3-carbon molecules called “pyruvate”
• This process is an “ancient one” because all organisms from simple bacteria to humans perform it the same way
• Yields 2 ATP molecules for every one glucose molecule broken down
Anaerobic Cellular Respiration
• Some organisms thrive in environments with little or no oxygen• Marshes, bogs, gut of animals,
sewage treatment ponds
• No oxygen used= ‘an’aerobic
• Results in no more ATP, final steps in these pathways serve ONLY to regenerate NAD+ so it can return to pick up more electrons and hydrogens in glycolysis.
• End products such as ethanol and CO2 (single cell fungi (yeast) in beer/bread) or lactic acid (muscle cells)
Aerobic Cellular Respiration
• Oxygen required=aerobic
• Steps 2 & 3 of cell respiration will occur in succession in the presence of oxygen. This set of reactions will occur in a specialized structure within the cell called the mitochondria• 2. Kreb’s Cycle
• 3. Electron Transport Chain
KREB’s Cycle &The ETC
A Little Krebs Cycle History
Discovered by Hans Krebs in 1937
He received the Nobel Prize in physiology &medicine in 1953 for his discovery
Forced to leave Germany prior to WWII because he was Jewish
2. Kreb’s Cycle / Citric Acid Cycle
• Completes the breakdown of glucose• Takes both pyruvates and simultaneously
completes the reaction needed to break down the each pyruvic acid into CO2 and H2O
• Hydrogens and electrons are stripped and loaded onto NAD+ and FAD to produce NADH and FADH2
• Yields only 2 more ATP but loads up the coenzymes with H+ and electrons which move to Step 3.
What is NAD or NADH?
NAD+ (nicotinadeninedinucleotide) acts as the energy carrier by carrying electrons
NAD+ is a “coenzyme”
It’s Reduced to NADH when it picks up two electrons and one hydrogen atom (hence the name, NAD+H)
INACTIVESTATE
ACTIVESTATE
Coenzymes
Other Electron Carriers
FAD+ (Flavin adenine dinucleotide)
Also a coenzyme!
Reduced to FADH2
• Both NAD & FAD are election carriers. The main difference seen between in the two is in accepting the excess Hydrogen Atoms.
• NAD is reduced when it accepts a single hydrogen whereas FAD is reduced by a two Hydrogen atoms, hence their names NADH and FADH2.
Cytoplasm
Net Gain = 2 ATP Net Gain = 2 ATP
KREB’s Cycle
In Depth Look
Cytoplasm
3. Electron Transport Chain
• Electron carriers loaded with electrons and protons from the Kreb’s cycle move to this chain-like a series of steps (staircase).
• As electrons drop down stairs, energy released to form a total of 34 ATP
• Oxygen waits at bottom of staircase, picks up electrons and protons and in doing so becomes water
• HAPPENS IN THE CRISTAE of the MITOCHONDRIA
Diagram of the Process
Occurs in Cytoplasm
Occurs in Matrix
Occurs across Cristae
Cytoplasm
Energy Tally
• 36 ATP for aerobic vs. 2 ATP for anaerobic
• Glycolysis 2 ATP
• Kreb’s 2 ATP
• Electron Transport 34 ATP38 ATP
- 2ATP to get Glycolysis started! - “TOTAL” ATP produced – 38 ATP- “Net Gain” ATP produced – 36 ATP
• Anaerobic organisms can’t be too energetic but are important for global recycling of carbon