Question

Add coefficients to the reaction summary to show the net results of glycolysis. glucose+a ADP+b Pi+c NAD+⟶x pyruvate+y ATP+z NADH You do not need to add the water and hydrogen ions necessary to balance the overall reaction.

Then, Draw the structure of pyruvate at pH 7.4.

Answer 1

For the glycolysis reaction: Glucose + 2 ADP + 2 Pi + 2 NAD+ → 2 Pyruvate + 2 ATP + 2 NADH + 2 H+, with a = 2, b = 2, c = 2, x = 2, y = 2, z = 2. Pyruvate's structure at pH 7.4 will have a deprotonated carboxyl group, represented as C3H3O3-.

Step-by-step explanation:

To add coefficients to the reaction summary that shows the net results of glycolysis, we look at the overall stoichiometry of the process. Glycolysis involves the breakdown of glucose to form pyruvate, ATP (adenosine triphosphate), and NADH (reduced form of nicotinamide adenine dinucleotide). For one molecule of glucose, the complete glycogenetic pathway can be summarized as follows:

Glucose + 2 ADP + 2 Pi + 2 NAD+ → 2 Pyruvate + 2 ATP + 2 NADH + 2 H+

Here, a=2, b=2, c=2, x=2, y=2, and z=2, respectively. When writing the structural formula for pyruvate at physiological pH (7.4), the carboxylic acid group will exist predominantly as its conjugate base, the carboxylate anion, since the pKa of a carboxylic acid is typically lower than 7.4. Therefore, the structure of pyruvate at pH 7.4 is:

C3H3O3-

In this form, the carboxyl group (-COOH) is deprotonated to become -COO-.

Answer 2

See figure 1

Step-by-step explanation:

For this question, we can start with the structure of pyruvic acid. In this molecule, we have two functional groups, the ketone group, and a carboxylic acid group.

In the acid group, we have an acidic hydrogen. That is, this hydrogen can leave the molecule to produce a hydronium ion (
`H^+`).

Now, to know what is the pH at which this hydrogen leaves the molecule we must look for the pKa value. Which for the case of this molecule is 2.45

If there is a pH value greater than 2.45, the molecule will lose hydrogen. In this case, we will have a value above 2.45 (7.4), which is why the conjugated acid of pyruvic acid will be produced, which is pyruvate.

Therefore, in the structure, we will have a negative charge on the acid group.

See figure 1

I hope it helps!