Question

Antibacterial medications that inhibit protein synthesis in prokaryotes target the 70s ribosome. However, human cells possess ribosomes similar to those of bacteria, which might account for some of the toxicity observed with some of these drugs.

a. 60s and 40s ribosomes
b. 80s and 50s ribosomes
c. 70s and 30s ribosomes
d. 90s and 60s ribosomes

Answer 1

Antibacterial medications target the 70S ribosomes in bacteria, which are different from the 80S ribosomes in human cells. Some antibiotics cause side effects due to their interaction with 70S ribosomes within human mitochondria. The specificity of antibiotics for bacterial ribosomal subunits is key to their function and potential toxicity.

Step-by-step explanation:

Inhibitors of Protein Synthesis in Prokaryotes

Antibacterial medications that inhibit protein synthesis in prokaryotes often target the 70S ribosomes, which are distinct from eukaryotic ribosomes found in human cells. Human ribosomes are made up of 60S and 40S subunits, combining to form an 80S ribosome, while bacterial ribosomes comprise 50S and 30S subunits to form a 70S ribosome. The differences in subunit composition between eukaryotic (human) and prokaryotic (bacterial) cells are exploited by antibiotics to selectively target bacteria. Bacterial protein synthesis inhibitors, such as aminoglycosides, tetracyclines, macrolides, lincosamides, chloramphenicol, and oxazolidinones, are designed to specifically bind to the 30S or 50S subunit of bacterial ribosomes. Tetracycline, for instance, blocks tRNA binding to the ribosome, while chloramphenicol inhibits peptidyl transfer, obstructing the growth of the protein chain. Although these antibiotics are selective for bacterial ribosomes, some side effects in human cells may occur due to the presence of 70S ribosomes within human mitochondria, similar to those in bacteria.

Aminoglycosides are another class of compounds that bind to the 30S subunit, leading to the production of faulty proteins that can result in cell death, although they may also cause toxicity in humans. When utilizing antibiotics, it is crucial to consider the potential side effects that can result from their interaction with the eukaryotic ribosomes within human mitochondria, leading to drug toxicity.

Answer 2

Antibacterial medications that inhibit protein synthesis in prokaryotes target the 70s ribosome. However, human cells possess ribosomes similar to those of bacteria, which might account for some of the toxicity observed with some of these drugs. c. 70s and 30s ribosomes.

Step-by-step explanation:

The correct answer is c. 70s and 30s ribosomes. Antibacterial medications that inhibit protein synthesis in prokaryotes target the 70s ribosome, which is composed of a 50s and a 30s subunit. Human cells, on the other hand, possess 80s ribosomes, consisting of a 60s and a 40s subunit.

The discrepancy in ribosome structure between bacteria and human cells forms the basis for the selectivity of antibiotics. Drugs targeting the 70s ribosome in bacteria can interfere with bacterial protein synthesis without significantly affecting human cells.

However, there is a degree of similarity between bacterial and mitochondrial ribosomes (found in eukaryotic cells), and this is the reason behind some of the toxicity observed with certain antibacterial drugs.

When antibiotics affect mitochondrial protein synthesis, it can lead to side effects and toxicity in human cells. Mitochondria are thought to have evolved from free-living bacteria, and their ribosomes are structurally similar to bacterial ribosomes. Therefore, drugs targeting bacterial protein synthesis may inadvertently impact mitochondrial function in human cells.

Understanding these nuances is crucial in developing and using antibiotics to minimize side effects and optimize therapeutic outcomes. It emphasizes the importance of precise drug targeting to ensure efficacy against bacterial infections while minimizing harm to human cells.