Count the number of carbon, hydrogen, and oxygen atoms in pyruvic acid and lacti
ID: 89489 • Letter: C
Question
Count the number of carbon, hydrogen, and oxygen atoms in pyruvic acid and lactic acid. Write the chemical formula for pyruvic acid and lactic acid below. How does the total number of hydrogen atoms change when pyruvic acid is converted to lactic acid? Explain how the conversion of NADH + H^+ to NAD^+ couples with the conversion of pyruvic acid to lactic acid. Identify which molecule is oxidized and which is reduced during the reaction. Explain how this anaerobic reaction contributes to the goal of harvesting energy from glucose.Explanation / Answer
1. ANS:
A. Pyruvic acid:
Formula: C3H4O3
Number of carbon atoms is 3
Number of hydrogen atoms is 4
Number of oxygen atoms is 3
B. Latic acid:
Formula: C3H6O3
Number of carbon atoms is 3
Number of hydrogen atoms is 6
Number of oxygen atoms is 3
2. ANS: Pyruvic acid supplies energy to living cells through the citric acid cycle (also known as the Krebs cycle) when oxygen is present (aerobic respiration); when oxygen is lacking, it ferments to produce lactic acid.
The enzyme lactate dehydrogenase helps in the process of pyruvic acid convert into lactic acid. In this reaction the addition of two H+ to pyruvic acid forms NAD and lactic acid
3. ANS: Under anaerobic conditions, the electron transport system no longer functions; therefore, the pyruvate produced at the end of glycolysis is reduced to lactate and NADH is oxidized back to NAD+ .
Lactic Acid Fermentation Reaction occurs in cells without mitochondria (RBC) or in cells when O2 is limited (muscle cells during exercise). The entire purpose of this reaction is to convert the NADH produced in step 6 of glycolysis back to NAD+ so that glycolysis can continue.
4. ANS: This is simply a redox reaction in which pyruvate is reduced to lactate by the enzyme lactate dehydrogenase.
5. ANS:
Glucose + 2Pi + 2ADP 2 lactate + 2ATP + 2 H2O
Glucose must be converted to lactate, 2 ATP produced.
Lactate can then enter the bloodstream and travel to the liver where it is converted back to glucose through the gluconeogenesis pathway.