EVOLUTION CONNECTION • DRAW IT Medical researchers seek to develop drugs that can kill or restrict the growth of human pathogens yet have few harmful effects on patients. These drugs often work by disrupting the metabolism of the pathogen or by targeting its structural features. Draw and label a phylogenetic tree that includes an ancestral prokaryote and the following groups of organisms: Excavata, SAR, Archaeplastida, Unikonta, and, within Unikonta, amoebozoans, animals, choanoflagellates, fungi, and nucleariids. Based on this tree, hypothesize whether it would be most difficult to develop drugs to combat human pathogens that are prokaryotes, protists, animals, or fungi. (You do not need to consider the evolution of drug resistance by the pathogen.)

Key Concepts

Phylogenetic Tree

A phylogenetic tree is a diagram that represents the evolutionary relationships among various biological species based on their genetic or physical characteristics. It illustrates how different groups of organisms are related through common ancestors, allowing researchers to visualize evolutionary pathways. In this context, the tree will help identify the evolutionary distance between human pathogens and other organisms, which is crucial for understanding drug development challenges.

Prokaryotes vs. Eukaryotes

Prokaryotes are single-celled organisms that lack a nucleus and membrane-bound organelles, while eukaryotes have a defined nucleus and complex cellular structures. This distinction is significant in drug development, as prokaryotic pathogens (like bacteria) may have different metabolic pathways and structural features compared to eukaryotic pathogens (like fungi and protists). Understanding these differences is essential for targeting drugs effectively without harming human cells.

Drug Targeting Mechanisms

Drug targeting mechanisms refer to the strategies used to design pharmaceuticals that specifically affect pathogens while minimizing harm to human cells. These mechanisms can involve disrupting metabolic processes unique to the pathogen or targeting structural features that differ from those in human cells. The effectiveness of these strategies can vary significantly between prokaryotes, protists, animals, and fungi, influencing the difficulty of developing effective treatments.