9'3 Cellular Respiration: Harvesting Chemical Energy to Make ATP

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• 9.3 Cellular Respiration Harvesting Chemical
  Energy to Make ATP

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How can cells replenish ATP?

• CELLULAR RESPIRATION
• uses food and breathing to make E
• (glucose) (oxygen) (ATP)
• ? THE GENERAL EQUATION
• C6H12O6 6O2 38ADP 38Pi ?
• 6CO2 6H2O 38ATP

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How can cells replenish ATP?

• BUT
• To break the glucose we use 2 ATPs so what is
  the net ATP from cellular respiration?
• Cellular Respiration takes the energy in glucose
  to make ATPs
• Aerobic Respiration Using oxygen to make Energy

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Cellular Respiration

• 3 Steps
• Glycolysis
• Citric Acid Cycle
• Electron Transport Chain
• Also called oxidative phosphorylation

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Cellular Respiration STEP 1

• Glycolysis
• Oxygen is NOT required!
• Glucose is split to form pyruvate.
• Takes place in the cytoplasm of the cell.
• ATP is a byproduct.

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Cellular Respiration STEP 1

• Glycolysis
• Glucose 2ATP 2NAD ?2 Pyruvic Acid 4ATP
  2NADH
• (pyruvate)
• Not very efficient to make more ATP cells must
  move on to step II and III (only if O2 is
  present)
• NAD Coenzyme which carries electrons (Hs) to
  make NADH (used later to make ATP)

Why is this only 2 ATP?
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Cellular Respiration STEP 1

• Pyruvate now moves into the mitochondria step 2

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Cellular Respiration STEP 2

• Citric Acid Cycle (Krebs)
• Pyruvate is used to build citric acid (a carbon
  compound), which is broken down to release ATP.
• Takes place in the cristae (the folded membrane
  in the mitochondrion).
• CO2 is released
• NADH FADH2 carry hydrogen ions electrons to
  the electron transport chain (step 3)

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Cellular Respiration STEP 2

• Citric Acid Cycle (Krebs cycle)
• Pyruvic acid oxidizes (breaks) into Acetyl-CoA
• happens PRIOR to the cycle
• Also made NADHs, FADH2, GTP (converts to ATP)

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Formation of Acetyl CoA
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Cellular Respiration STEP 2

• CITRIC ACID CYCLE
• 2-C (acetyl-coA) 4-C (oxaloacetic acid) 6-C
  (citric acid)
• The 4-C molecule is recycled
• Releasing 2 Cs as.
• Cycle turns twice WHY?

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Cellular Respiration STEP 3

• Electron Transport Chain
• hydrogen ions are stripped of their energy
  large amounts of ATP are formed.
• Takes place in the inner membrane of the
  mitochondrion.
• The used ions are combined with oxygen to form
  H2O.
• Also called oxidative phosphorylation

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Cellular Respiration STEP 3

• Electron Transport Chain
• H concentration gradient builds
• NADH and FADH2 pass electrons (Hs) to water
• Flow of H to matrix through ATP synthase protein
  channel ? ADP into ATP (34)
• H and O make H2O

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Electron Transport Chain Animation

• http//www.science.smith.edu/departments/Biology/B
  io231/etc.html

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Cellular Respiration SUMMARY
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Cellular Respiration SUMMARY

• C6H12O6 6O2 ? 6CO2 6H2O Energy
• (glucose) (breath) (used in photosyn.)
  (ATPs)

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Heat
Electron Transport System
O2
ATP
H2O
NADH
NAD
CO2
citric acid cycle
Glucose
ATP
Pyruvate
MITOCHONDRION
ATP
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Sunlight
Heat
O2
Photo- System I
Photo- system II
Electron Transport System
ATP
H2O
ATP
NADP ADP
NADPH
NAD
NADH
CO2
Calvin
Citric Acid
Cycle
Cycle
ATP
Glucose
Pyruvate
CHLOROPLAST
MITOCHONDRION
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Cellular respiration
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What if O2 is not present?

• Anaerobic Respiration
• Making E without oxygen
• Glycolysis can still occur
• Its an ANAEROBIC AEROBIC process
• This is NOT efficient enough why?
• Two types of respiration occurring without
  oxygen
• Lactic Acid Formation
• Fermentation

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What if O2 is not present?

• Lactic acid fermentation in muscles
• When O2 runs out, but glucose is still starting
  to break down into pyruvate
• C6H12O6 4ADP 4Pi? 2CH3CHOHCOOH 4ATP
• (lactic acid/lactate)
• Note the ATP difference
• Converts pyruvate to lactate (lactic acid)

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What if O2 is not present?

• Alcoholic fermentation in plants (foods)
• Makes CO2 and ethanol (an alcohol)
• C6H12O6 4ADP 4Pi ? 2C2H5OH 2CO2 4ATP
• (ethnaol)
• Converts pyruvate to lactate (lactic acid)

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