Fungi and Parasites: The Eukaryotic Pathogens Quiz

See The Eukaryotic Targeting Problem. Option E is correct because humans, fungi and protozoa (single-celled parasites) are all eukaryotes. Every eukaryotic cell keeps its DNA inside a nucleus surrounded by a nuclear membrane, makes proteins on ribosomes, and organises its chemistry in membrane-bound organelles such as mitochondria (the structures that release energy). Bacteria are prokaryotes: they have no nucleus and usually carry a single circular chromosome in a region called the nucleoid. This shared design has a practical consequence for treatment. With a bacterial infection, many essential structures differ sharply from human ones, so antibiotics can be selective. With a fungal or protozoal infection, far fewer essential targets are unique to the pathogen, so a drug that harms the pathogen is more likely to harm the patient too. Memory aid: eukaryote means true nucleus.

• Eukaryotes: humans, fungi and protozoa keep their DNA in a nucleus and use membrane-bound organelles.
• Bacteria: prokaryotes with no nucleus and usually a single circular chromosome in the nucleoid.
• Treatment: few essential targets are unique to fungi and protozoa, so a drug that harms the pathogen is more likely to harm the patient.