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Zorluk: ZorHealth, Nutrition, and Disease

Medical treatments for infectious diseases rely on the principle of selective toxicity, which involves destroying or inhibiting a pathogen without harming host tissues. While bacterial infections can often be effectively treated by targeting prokaryotic structures like peptidoglycan cell walls or 70S ribosomes, treating systemic infections caused by fungi or protozoans in humans carries a significantly higher risk of adverse toxic side effects. Which of the following best explains why developing safe pharmacological treatments against fungal and protozoan pathogens is more difficult than treating bacterial infections?

  1. A
    Fungi and protozoans are acellular infectious particles that lack metabolic machinery, forcing therapeutic drugs to destroy host cell membranes to reach them.
  2. B
    Fungi and protozoans are prokaryotic organisms protected by dense peptidoglycan walls that prevent chemical diffusion into their cytoplasm.
  3. Fungi and protozoans are eukaryotic organisms that share fundamental metabolic pathways, ribosomal structures, and cellular organelles with human cells.Cevap
  4. D
    Fungi and protozoans replicate solely by inserting their genetic code into host chromosomes, rendering cytoplasmic antimicrobial agents ineffective.

Cevap

Fungi and protozoans are eukaryotic organisms that share fundamental metabolic pathways, ribosomal structures, and cellular organelles with human cells.
Selective toxicity requires exploiting structural and biochemical differences between the invading pathogen and the host organism. Bacteria are prokaryotes, providing distinct drug targets like peptidoglycan cell walls and 70S ribosomes that human cells lack. However, fungi and protozoans are eukaryotic organisms containing membrane-bound organelles, linear chromosomes, 80S ribosomes, and metabolic pathways closely related to those of human cells. Consequently, therapeutic compounds that disrupt essential fungal or protozoan cellular functions frequently cause cross-reactivity and toxic side effects in human tissues.

Adım Adım Çözüm

1
Identify the biological domain and cellular classification of the pathogens in question.
Bacteria are prokaryotes, whereas fungi, protozoans, and human host cells are all eukaryotes.
Understanding the fundamental domain of life for each pathogen determines its underlying cellular machinery and organelle composition.
2
Evaluate the mechanism of selective toxicity across different pathogen classes.
Antibacterial agents easily achieve selective toxicity because bacteria possess unique targets absent in human cells (such as peptidoglycan walls and 70S ribosomes). In contrast, eukaryotic pathogens share 80S ribosomes, similar protein synthesis pathways, and homologous enzymes with human host cells.
Drugs must target biochemical or structural differences to kill pathogens without harming the host.
3
Synthesize the biological challenge of treating eukaryotic infections.
Compounds designed to disrupt fungal or protozoan enzymes frequently cross-react with human cellular homologues, leading to increased host toxicity and side effects.
Close evolutionary and cellular homology between host and eukaryotic pathogen minimizes the number of unique pharmacological targets.

Anahtar Kavram

Selective Toxicity and Cellular Classification of Pathogens
Tahmini Süre:1m 30s
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Health, Nutrition, and Disease

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