Transcript anaerobic respiration

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
Reduction
- loss of electrons
- gain of oxygen
- loss of hydrogen
- ON more positive
- gain of electrons
- loss of oxygen
- gain of hydrogen
- ON less positive
REDOX
reaction
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
oxidation
C6H12O6 + 2NAD+  2 C3H3O3 - + 2NADH + 4H+ + energy
reduction
NAD+ and NADH
Glycolysis
Stage Two – Aerobic or Anaerobic
Respiration
• Aerobic or Anaerobic respiration follows
depending on whether O2 is available or not.
O2
Pyruvate
No O2
CO2 + H2O aerobic respiration
No O2
lactic acid
anaerobic respiration
Ethanol
anaerobic 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 One
C6H12O6 + 2NAD+  2 C3H3O3 - + 2NADH + 4H+ + energy
Stage Two
2 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 Cu
Fe 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 ATP
Pyruvate
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 ATP
Pyruvate
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 acid
conjugate 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