Download RESPIRATION AND FERMENTATION: AEROBIC AND ANAEROBIC

RESPIRATION AND
FERMENTATION: AEROBIC
AND ANAEROBIC OXIDATION
OF ORGANIC MOLECULES
Bio 107 – Week 6
Procedure 7.2

1)
2)
3)
4)
5)
Label test tubes well, including group name
Add solutions listed to small test tubes
Fill remaining volume with yeast suspension
Slide larger test tube over the smaller tubes; hold
smaller tube against the bottom of the larger tube and
invert. There should be no air trapped at the top of
the tube. Practice this first with just water.
Incubate tubes at 37˚C for 30 minutes.
After 30 minutes, measure the height (in millimeters) of
the bubble of accumulated CO2. Record results in
table 7.2
Tips and Tricks



Shake yeast bottles before using
Clean benches immediately when done (this stuff
gets sticky)
Rinse test tubes well and put upside-down in rack at
table.
Cellular Respiration

Cellular Respiration: oxidation of organic molecules
into energy in the form of ATP
 ATP
= Adenosine Triphosphate: organic molecule
containing high-energy phosphate bonds
Cellular Respiration - Summary
C6H12O6 + 6O2



Glucose is oxidized [removes electrons], O2 is reduced
(oxidation-reduction reaction or REDOX)
Remember OIL RIG – Oxidized Is Loss (of electrons) and
Reduction Is Gain)
Remember that adding/removing a hydrogen is a way of
adding/removing an electron


6CO2 + 6H20 + e- + 36-38ATP
One glucose yields 36-38 ATP
Electrons (as H) moved by coenzymes NAD+ and NADH2
Steps of Cellular Respiration




Glycolysis
Prep Reactions
Krebs Cycle
Electron Transport
Chain
Respiration: Glycolysis

Energy Investment Step


Two ATP used to split glucose into two 3-carbon molecules
Energy-Harvesting Step
1) 3-carbon molecules oxidized by NAD+, resulting in two NADHs
 2) Phosphate group added to each.
 3) Substrate-level ATP synthesis or substrate-level phosphorylation:
enzyme passes high-energy phosphate to ADP, and ATP results
(adenosine diphosphate triphosphate (+2 ATP, 3PG (3phosphoglycerate))
 4) 3PG is oxidized by the removal of water (+2H2O, 2 PEP)
 5) Substrate-level ATP synthesis again. (+2 more ATP, 2 pyruvate)
 NET GAIN: 2 ATP, (because we used two in energy investment) +
2 pyruvate.

Respiration: Glycolysis




Glycolysis: “Sugar-splitting” or “Energy investing” step
Occurs in cytoplasm
Requires 2ATP
Glucose split into 2 Pyruvate
Respiration: First Set of Reactions

Glycolysis: “Sugar-splitting” or “Energy investing” step
Occurs in cytoplasm
Requires 2ATP
Glucose split into 2 Pyruvate

Final Products:



2 NET ATP (4 produced, but 2 were used)
 2 NADH
 2 Pyruvate

If Oxygen is Present…

Prep Reactions



Citric Acid Cycle





Pyruvate oxidation into acetyl-CoA
One NADH produced
Occurs in matrix of mitochondria
Acetyl-CoA oxidized into two CO2
Produces 1 ATP per turn
Store energy in electron carries such as
NAD+ and FAD+
Electron Transport Chain


Electrons from NADH and FADH2 move
through a series of proteins called the ETC
Potential energy released during these
redox reactions creates proton gradient
across a membrane; flow of protons across
the membrane generates ATP
If No Oxygen is Present…





NADH reduces Pyruvate
C6H12O6  2CO2 + 2C2H5OH + ATP
C6H12O6  2CH3CHOHOCOOH + ATP
Occurs in anaerobic organisms (anaerobes)
Occurs temporarily in plants and animals


Roots in anaerobic soils
Animals, some
In muscles for rapid bursts of energy
microbes
Glucose
Glycolysis
Pyruvate
Plants, some
microbes
NADH
NADH
CO2
NAD+
Lactate
NAD+
Ethanol
Yeast – our organism





Unicellular sac fungi –
eukaryotes, kingdom Fungi,
phylum Ascomycota
Obtain food from organic matter
In the wild – found in soil, water,
surface of animals and plants
Many species/strains used to
make bread, beer, whiskey and
more!
Also can cause disease
(Candida, opportunistic)
What undergoes Fermentation?

Anaerobes – organisms that live without oxygen
 Some
use nitrate, sulfate or other inorganic compounds
as electron acceptors instead of oxygen
 Some use glycolysis reduce the pyruvate

Other organisms can undergo fermentation when
their cells are depleted of oxygen (such as during
exercise)
Advantages/Disadvantages?

Disadvantages:
 Less
ATP produced (2 VS 36/38 in aerobic respiration)
 Produces toxins (lactic acid or ethanol)

Advantages:
 Can
produce ATP without oxygen – survival!
 Byproducts used in many foods (economic value, not a
biological advantage)
Lab Results
Table 7.2 – Fermentation By Yeast
Tube
Sugar
1
Water/None
2
Glucose
3
Fructose
4
Sucrose
Glucose
Initial Gas
Height
Final Gas
Height
Net Change
Ease of
Fermentation
(Rank)
Sucrose
Procedure 7.2

1)
2)
3)
4)
5)
Label test tubes well, including group name
Add solutions listed to small test tubes
Fill remaining volume with yeast suspension
Slide larger test tube over the smaller tubes; hold
smaller tube against the bottom of the larger tube and
invert. There should be no air trapped at the top of
the tube. Practice this first with just water.
Incubate tubes at 37˚C for 30 minutes.
After 30 minutes, measure the height (in millimeters) of
the bubble of accumulated CO2. Record results in
table 7.2
Tips and Tricks



Shake yeast bottles before using
Clean benches immediately when done (this stuff
gets sticky)
Rinse test tubes well and put upside-down in rack
by the sink.