Cellular Respiration

1
Cellular Respiration

• Obtain energy from the degradation of sugars
• Uses Oxygen and produces CO2
• Many steps take place in the mitochondria of
  cells
• Complementary process to photosynthesis
• Will recognize many of the same molecules

2
Oxidation-Reduction reactions

• Type of reaction when an electron is transferred
  from one atom or molecule to another
• Electron donor is reducing agent
• Electron acceptor is oxidizing agent
• The addition of electron to a molecule or atom is
  called reduction
• Energy is released when electrons are transferred
  to lower energy state molecules
• Electron transfer chains

3
Cellular Respiration Mechanisms

• 3 Stages
• Glycolysis-happens in cytosol of cell
• Krebs cycle-happens in matrix of mitochondria
• Electron transport and oxidative
  phophorylation-cristae

4
Glycolysis

• Means sugar splitting-glucose is split into
  Pyruvate
• First step of respiration
• Broken into two stages
• Energy investment phase-uses 2ATP
• Energy Payoff Phase-Yields 4 ATP 2 NADH
• Net of 2 ATP

5
Energy Investment Phase

• Begins with Glucose
• 2 ATPs are used to phosphorylate Carbons 1 and 6
• Activated intermediates
• Isomerase converts glucose to fructose structure
• Isomerase is enzyme that changes one molecule to
  an isomer
• Eventually yields 2 molecules of glyceraldehyde
  phosphate
• Enters energy payoff phase

6
Energy Payoff Phase

• Starts with Glyceraldehyde phosphate
• 2 for every glucose
• Enzyme adds phosphate GP while 2 NADH molecules
  are produces
• Phosphates are eventually loss resulting in the
  production of 4 ATP molecules
• The final product is Pyruvate
• Moves into Krebs cycle

7
Transition

• Once Pyruvate enters Mitochondrion it is
  converted to Acetyl CoA and CO2
• Acetyl CoA is the starting molecule for the Krebs
  cycle

8
Krebs cycle

• Completes the oxidation of organic molecules
• Takes place in matrix of mitochondria
• Cyclic like Calvin cycle
• Produces 1 ATP for each acetyl CoA
• 2 per glucose
• Many high energy electrons are saved as 3NADH and
  FADH2 per cycle
• Also produces 2 CO2 molecules per cycle

9
Krebs Cycle 2
10
Transition 2

• NADH and FADH2 are used in the electron
  transport chain
• Happens in cristae of mitochondrion
• Uses Oxygen as ultimate electron acceptor