Tag: cell respiration

The breakdown of glucose to form ethanol and carbon dioxide is known as alcoholic fermentation. This takes place in the cytoplasm of cells. The substrate is glucose which undergoes glycolysis to form pyruvate. This pyruvate is then converted into acetaldehyde after the removal of one carbon and then ethanol is formed along with carbon dioxide.

• Lactic acid fermentation does not involve decarboxylation and results in the production of lactic acid and NAD$^{+}$.
  
• Alcoholic fermentation involves decarboxylation and produces CO$ _{2}$ along with ethanol.
  
• Aerobic respiration uses oxygen and glucose to produce CO$ _{2}$ and water as shown below:
        C$ _{6}$H$ _{12}$O$ _{6}$ + 6O$ _{2}$ $\rightarrow$ 6CO$ _{2}$ + 6H$ _{2}$O + energy (heat and ATP)

Fermentation is a type of anaerobic respiration in which the glucose is converted to release gases, acids and alcohols.

In lactic acid fermentation, the 3-carbon pyruvate is converted to the 3-carbon lactic acid. Also NAD$^{+}$ is regenerated in the process, allowing glycolysis to continue to make ATP in anaerobic conditions. Hence lactate and NAD$^{+}$ are the direct products and ATP is the indirect product of lactic acid fermentation. NADH act as a reducing agent here, while CO$ _{2}$ is a product of alcohol fermentation.

Answer is option A i.e. "Pasteur effect"
Pasteur effect is exhibited in yeast cells during anaerobic fermentation. Pasteur effect influences the rate of glycolysis and occurs in presence of oxygen which  decreases the rate of sugar breakdown in yeast.
While, Blackman's law and Emerson effect is related to determining the rate of  photosynthesis. Chargraff's rule is a rule for base equivalence in DNA.

A) Lactic acid fermentation is the process that occurs after glycolysis when there is lack of oxygen.

Fermentation is a type of anaerobic respiration in which the glucose is broken down into pyruvic acid in the absence of oxygen. During fermentation of sugars, this pyruvic acids coverts to a 2C acetaldehyde and then to ethanol and CO₂. All this takes place in the cytoplasm.

Unicellular organisms like yeast undergo an alternate pathway of respiration in which an organic substrate is broken down in absence of oxygen. The end products are alcohol and CO$ _2$. Such a process is called alcoholic fermentation. In Yeast, the fermentation products are ethyl alcohol and carbon dioxide.

Conversion of sugar to alcohol directly was found in yeast fermentation in which glucose was converted to ethyl alcohol and CO$ _2$. The conversion happens in presence of an enzyme called zymase which is found naturally in yeast. So, the answer is 'Zymase'.