Final answer:
Antibiotics kill bacteria by targeting bacterial ribosomes, which differ from human ribosomes, minimizing harm to human cells. However, certain side effects may occur because of similarities with mitochondrial ribosomes in human cells. Developing medications targeting other eukaryotes or viruses is more challenging due to their structural similarities with human cells.
Step-by-step explanation:
Some drugs, known as antibiotics, are able to kill bacteria without harming human cells because they target structures that are specific to bacteria. The difference between bacterial ribosomes (70S) and human ribosomes (80S) is a key point in the development of these drugs. Bacterial ribosomes are made up of 30S and 50S subunits, while human ribosomes are composed of 40S and 60S subunits. In addition, though mitochondria within human cells do contain ribosomes similar to those found in bacteria, most antibiotics are selectively more toxic to bacterial cells than to human mitochondria.
Specific antibiotics such as erythromycin and other macrolide antibiotics bind to the 50S ribosomal subunit of bacteria, disrupting their protein synthesis which is crucial for their survival. This is because human cells do not have the 50S subunit that these antibiotics target. Furthermore, because these medications finely target bacterial ribosomes, it minimizes the effect on human cells, although sometimes side effects may occur.
It is more challenging to develop medications that are effective against eukaryotic cells such as fungi and protozoans without harming human cells due to the similarities in cellular structures. Moreover, this specificity makes it difficult to develop drugs that can target viruses since they replicate within human cells.