Final answer:
The two enzymes least likely to be functional within a mammalian organism are RNA Ligase and Ribonuclease, given that RNA Ligase is not involved in mammalian DNA replication and Ribonuclease's role is less prominent compared to the necessity of amylase for digestion and DNA polymerase for DNA replication.
Step-by-step explanation:
The two enzymes least likely to be functional within a mammalian organism from the options provided are c) RNA Ligase and d) Ribonuclease. Mammals do not use RNA Ligase because the joining of Okazaki fragments and the repair in DNA replication and recombination involves DNA ligase, not RNA ligase. As for ribonuclease, while it does play a role in RNA processing and degradation, its function as a generic enzyme is overshadowed by the constant need and high functionality of amylase and DNA polymerase in mammals. Amylase is critical for carbohydrate digestion, as it breaks down starch into sugars, and DNA polymerase is essential for DNA replication, particularly for adding nucleotides to a new DNA strand and proofreading.
DNA polymerase is crucial in the DNA replication process, specifically DNA polymerase III, which adds nucleotides to the new DNA strand, and DNA polymerase I, which not only removes the RNA primer but also fills in the necessary nucleotides during this process. Moreover, DNA ligase is the enzyme responsible for sealing nicks in the DNA backbone, such as those between Okazaki fragments during lagging-strand synthesis.