Giardia intestinalis can cause disease in several different mammalian species, including humans. Giardia organisms (G. intestinalis) that infect humans are similar morphologically to those that infect other mammals, thus they have been considered a single species. However, G. intestinalis has been divided into different subgroups based on their host and a few other characteristics. In 1999, a DNA sequence comparison study tested the hypothesis that these subgroups actually constitute different species. The following phylogenetic tree was constructed from the sequence comparison of rRNA from several subgroups of G. intestinalis and a few other morphologically distinct species of Giardia. The researchers concluded that the subgroups of Giardia are sufficiently different from one another genetically that they could be considered different species.

According to the phylogenetic tree in the figure above, G. intestinalis constitutes a ________ group.

#Question id: 3680

#SCPH28 | Zoology

If DNA polymerase I were mutated so that all its enzymatic activities were inactive, which part of replication would be most affected?

#Question id: 3681

#SCPH01 Biochemistry

 A mutated E. coli cell carries out and completes DNA replication, but the lagging strands are found to contain more errors than normal. These errors are not found evenly distributed throughout the lagging strands, but are found in clusters. Which enzymatic activity is missing from this cell?

#Question id: 3681

#SCPH05 I Biotechnology

 A mutated E. coli cell carries out and completes DNA replication, but the lagging strands are found to contain more errors than normal. These errors are not found evenly distributed throughout the lagging strands, but are found in clusters. Which enzymatic activity is missing from this cell?

#Question id: 3681

#SCPH06 I Botany

 A mutated E. coli cell carries out and completes DNA replication, but the lagging strands are found to contain more errors than normal. These errors are not found evenly distributed throughout the lagging strands, but are found in clusters. Which enzymatic activity is missing from this cell?

#Question id: 3681

#SCPH28 | Zoology

 A mutated E. coli cell carries out and completes DNA replication, but the lagging strands are found to contain more errors than normal. These errors are not found evenly distributed throughout the lagging strands, but are found in clusters. Which enzymatic activity is missing from this cell?

#Question id: 3682

#SCPH01 Biochemistry

A mutated strain of E. coli replicates DNA normally at 25°C, but replication stops immediately when the temperature is raised to 37°C. Which protein is likely to be non-functional at the higher temperature?