cellular respiration 1. the process by which glucose is converted is into carbon dioxide, water, and...
DESCRIPTION
Comparing Combustion to RespirationTRANSCRIPT
Cellular Respiration
1
Cellular Respiration• The process by which glucose is converted is into
carbon dioxide, water, and ENERGY
+ O2 CO2 + H2O + Energy
Comparing Combustion to Respiration
Review of Terminology
Oxidation - loss of electrons- gain of oxygen- loss of hydrogen
Reduction - gain of electrons- loss of oxygen- gain of hydroven
Review of Terminology
Oxidation - loss of electrons- gain of oxygen- loss of hydrogen- ON more positive
Reduction - gain of electrons- loss of oxygen- gain of hydrogen- ON less positive
REDOXreaction
Review of Terminology
aerobic- with O2
anaerobic - without O2
Stage One - Glycolysis
Anaerobic
1 mol glucose 2 mol pyruvate
C6H12O6 + 2NAD+ 2 C3H3O3 - + 2NADH + 4H+ + energy
Stage One - Glycolysis
Anaerobic
1 mol glucose 2 mol pyruvate
C6H12O6 + 2NAD+ 2 C3H3O3 - + 2NADH + 4H+ + energy
oxidation
reduction
NAD+ and NADH
Glycolysis
Stage Two – Aerobic or Anaerobic Respiration
• Aerobic or Anaerobic respiration follows depending on whether O2 is available or not.
Pyruvate
O2CO2 + H2O aerobic respiration
No O2
No O2lactic acidanaerobic respiration
Ethanolanaerobic respiration
Aerobic Respiration
Redox Reaction:
2 C3H3O3 - + 2NADH + 4H+ + 6O2 6CO2 + 6H2O + 2NAD+
pyruvate
Overall Reaction Adding together the rxns for Stage One and Stage Two gives the
overall reaction ….Stage OneC6H12O6 + 2NAD+ 2 C3H3O3 - + 2NADH + 4H+ + energy
Stage Two2 C3H3O3 - + 2NADH + 4H+ + 6O2 6CO2 + 6H2O + 2NAD+
C6H12O6 + 6 O2 6 CO2 + 6 H2O ∆ H = -2816 kJ/mol equivalent to 36 ATP
The Half Reactions
The overall redox rxn for aerobic respiration is made up the following two half rxns:
oxidation half reaction (C gets oxidized) C6H12O6 + 6 H2O 6CO2 + 24H+ + 24 e
reduction half reaction (O gets reduced) 6O2 + 24H+ + 24 e 12H2O
C6H12O6 + 6 O2 6 CO2 + 6 H2O
Aerobic Pathway for Pyruvate
The Role of Fe and CuFe and Cu in cytochromes are involved in moving the electrons
produced in the oxidation step to the reduction step • this occurs in the Electron Transport Chain • coupled to the oxidation step is a reduction involving Fe or Cu:
Fe3+ + e Fe2+ or Cu2+ + e Cu+
• coupled to the reduction step is an oxidation involving Fe or Cu:
Fe2+ Fe3+ + e or Cu+ Cu2+ + e
Energy Output
Goal – release the energy from glucose to fuel cell processes
- ATP is an energy storage molecule like a battery
- The conversion of ATP ADP releases stored energy (30.5 kJ/mol)
Energy Output
Exothermic
Endothermic
Energy Tally
Anaerobic Respiration• occurs during strenuous exercise when enough O2 is not
available for aerobic respiration
• lactic acid is produced which causes muscle cramping
• the overall redox reaction is: C3H3O3 - + NADH + H+ C3H5O3
- + NAD+ + energy as 2 ATPPyruvate Lactate The two half rxns that make up this redox rxn are:
Anaerobic Respiration• occurs during strenuous exercise when enough O2 is not available
for aerobic respiration
• lactic acid is produced which causes muscle cramping
• the overall redox reaction is: C3H3O3 - + NADH + H+ C3H5O3
- + NAD+ + energy as 2 ATPPyruvate Lactate oxidation half reaction NADH + H+ NAD+ + 2 e + 2 H+
reduction half reaction C3H3O3 - + 2 e + 2H+ C3H5O3
-
Anaerobic Respiration
Eventually O2 will again be available and the lactic acid will get oxidized to make CO2 and H2O by this overall redox reaction:
C3H6O3 + 3 O2 3 CO2 + 3 H2O + energy
Lactic acidconjugate acid for lactate ion
Fermentation• a form of anaerobic respiration that occurs in yeast • pyruvate is converted in ethanol 2 C3H3O3 - + 2NADH + 4H+ 2 CH3CH2OH + 2CO2 + 2NAD+
• adding the glycolyis reaction and this reaction gives the
overall fermentation reaction: C6H12O6 2 CH3CH2OH + 2 CO2
Two Anaerobic Pathways
Summary of the Aerobic and Anaerobic Pathways
Transport Processes in Cellular Respiration
1) Electron Transport Chain
• cellular respiration involves redox reactions • the Electron Transport Chain involves the movement of e’s in these
redox reactions • at the same time ADP gets released as ATP (energy out) • Cytochromes are Fe and Cu containing protein molecules that can
shuttle around e’s (see aerobic respiration above)
A Cytochrome Molecule
Transport Processes in Cellular Respiration
2) O2 Transport in the Blood• Haemoglobin is an oxygen transport protein• it consists of 4 heme groups:
Haemoglobin
• O2 gets moved through the blood by forming a dative bond with the iron in the heme group
• CO and CN- preferentially form dative bonds with the Fe in the heme group blocking the site from oxygen carbon monoxide poisoning or cyanide poisoning
Videos
• How NAD works• Glycolysis• ATP