Answer:
There is a drop in potential energy when reactants are converted into products. = True
Energy in the form of heat is released. = True
The reaction occurs when weak bonds are broken and stronger bonds are formed. = False
ATP is always one of the reactants. = False
The amount of entropy decreases when products are formed. = True
Explanation:
The monomers of nucleic acids are nucleotides, and we could imagine these molecules moving around in a very disordered manner. When these nucleotides are linked together by Condensation reactions, they would be more ordered. Would you expect these reactions to be spontaneous?
You may recall that in spontaneous reactions, the reactants are converted into products that typically have lower potential energy and higher entropy, which is a measure of Disorder. But when nucleotides polymerize, you would expect there to be less entropy in the products. So how can this process be spontaneous?
To overcome the reduction in entropy, nucleotides must first be activated by increasing their potential energy. This activation occurs by the addition of more phosphates. Recall that each of the linked phosphates is negatively charged, and the repulsion between these negatives charges makes the bonds between phosphates weak. These weak bonds increase the potential energy of the nucleotide. In other words, the potential to form new stronger bonds is increased.
In a condensation reaction between two activated nucleotides, two of the phosphates are removed as a much stronger bond formed between the remaining phosphate and hydroxyl on the 3 prime carbon of the other nucleotide. When this new bond is formed, the difference in bond strength results in a release of energy in the form of heat. Because of this large difference in bond strength, condensation reactions with activated nucleotides are spontaneous. What about Entropy?
As it turns out, the increase in molecular motion as heat is released from this reaction causes the level of Entropy to increase. This is similar to what occurs when ATP (Adenosine triphosphate), an activated nucleotide, reacts with water in the hydrolysis reaction. In this reaction, ATP is split into AMP and inorganic pyrophosphate. If we zoom in on the pyrophosphate, we can see that both products have formed new stronger wit atoms from water.
As a result, there would be a decrease in potential energy as the reactants are converted to products. This difference in energy, around 10.9 kilocalories, per mole of ATP is released as heat. A similar amount of heat energy is released in condensation reactions that link nucleotides together during polymerization.
