Cellular Respiration Lab Report

Cellular Respiration and Fermentation

Facts to Remember
1. Cellular respiration is a catabolic series of reactions.
2. All living forms conduct some form of cellular respiration, either aerobic or anaerobic.
a. Aerobic is in the presence of oxygen
b. Anaerobic is in the absence of oxygen or none oxygen requiring.

3. The starting molecules consist of the biological molecules with carbohydrates (monosaccharides) as the first choice. The order of use is given below.
a. Carbohydrates
b. Lipids„³acetyl CoA (via beta oxidation)„³ enters Krebs at the start site
c. Proteins„³amino acids-„³ enters glycolysis, transitional step or Krebs (point of entry is determine the carbon chain)
d. Nucleotides„³five carbon sugars„³ six carbon sugars
4.
Cellular respiration and fermentation produce energy in the form of ATP and key intermediates needed for anabolic reactions.
5. Cellular respiration and fermentation are redox reactions.

Aerobic Respiration
Model: Eukaryote Cell
Locations: cytoplasm, matrix of mitochondrion, inner mitochondrial membrane
Starting Molecules: Glucose (monosaccharide), 2 ATP, oxygen, and 2 NAD+
End Products: 38-40 ATP, CO2, H20, FAD+ and NAD+ (from FADH2 and 2 NADH + H+ via electron transport)

Step I: Glycolysis (an anaerobic process)
Important steps are sited, please see textbook for full explanation.

1. Glucose to glucose-6-phosphate: 1 ATP energy input
2. Fructose-6-phosphate to fructose 1,6, bis-phosphofructose: Committal Step
a. Under allosteric regulation
b. Allosteric modulators: ATP and Citrate
c. Determines whether glycolysis will continue
d. 1 ATP energy input

3. Fructose 1,6 bisphosphate is cleaved to form dihydroxyacetone phosphate (DAP) and glyceraldehydes 3 phosphate (G3P).
a. Cell prefers G3P, thus will ultimately convert DAP to G3P. Thus all reactions series from this point must be counted twice, once for G3P and secondly for DAP, after conversion.

4. G3P to 1,3 bis-phosphoglycerate
a. An inorganic phosphate is
used
b.
NAD+ „³ NADH + H+: a potential for ATP production in ETC
5. 1,3 bis- phosphoglycerate „³3 phosphoglycerate
a. ADP „³ATP: Method is substrate-level-phosphorylation (SLP)
6. 3-phosphoglycerate„³„³phosphoenol pyruvate
7. Phosphoenol pyruvate„³pyruvate + 1 ATP(via SLP)
8. Special Note: Pyruvate enters the matrix of mitochondrion

Glycolysis is over and has produced 4 ATP + 2 pyruvate + 2 NADH + H+

Step II: Transitional
Location: matrix of mitochondrion
Starting molecules: 2 pyruvate + 2 NAD+
End Products: 2 Acetyl CoA + 2 NADH+H+ + 2 CO2
Special Note: Acetyl CoA enters Krebs

Step III: Krebs Cycle
Location: Matrix of the Mitochondrion
Starting Molecules: oxaloacetate + acetyl CoA (2 per glucose from glycolysis)
End Products: 4CO2 + 2 ATP + 6 NADH + H+ +2 FADH2 *Oxaloacetate is regenerated

Special Note: NADH + H+ and FADH2 enter the electron transport
chain

Step IV: Electron Transport Chain: Chemiosmotic phosphorylation Facts to Remember
1. Several transport proteins are involved
i. Transmembrane complexes ii. Totally embedded transporters iii. Peripheral transporters
2. An intact membrane
3. A chemiosomotic gradient: pH or proton gradient (H+)

Please see textbook for a detailed drawing of the ETC.

Summations:
1. For each NADH + H+ that enters the electron transport chain, 3 ATP are produced
2. For each FADH2 that enters the electron transport chain, 2 ATP are produced.
3. Some transmembrane transporters shuttle electrons and hydrogen.
a. For example, FMN and FeS Complex
b. Coenzyme Q
4. Some transport electrons only, the cytochrome (cytc).
5. Electron transfer through the chain provides energy to pump hydrogen ions from the matrix to the inner compartmental space.
6. Electrons reenter the matrix at the cytochrome oxidase complex.
7. The final acceptor of electrons of the electron transport chain is oxygen.
8. The hydrogen ions in the inner compartmental space reenter the matrix via the Fo-F1 ATP synthetase complex. Approximately 1 ATP is produced per 2 H+.

Anaerobic Respiration: Fermentation

Step I: Glycolysis (the same as before)

Step II: The Fate of pyruvate and NADH + H+ is dependent on the organism or cell and the presence or absence of oxygen.

Scenario One: Lactic acid fermentation

Pyruvate + NADH + H+ „³Lactate + NAD+

Scenario Two: Alcohol Fermentation

Pyruvate „³Acetyl + NADH + H+ „³Ethanol + NAD+ + CO2