Part E What effect will the penicillin have on Shelly's cells? View Available Hint(s) The penicillin will not have any impact on Shelly's cells because it targets peptidoglycan, which is found only in bacteria. The penicillin will also kill some of Shelly's cells by disrupting the structure of the plasma membrane. There will be no impact on Shelly's cells because penicillin targets the flagella, which are found only in bacteria. Submit The penicillin will kill some of Shelly's cells because it targets the ribosomes, a structure found in both prokaryotes and eukaryotes. .

The correct answer is: **The penicillin will not have any impact on Shelly's cells because it targets peptidoglycan, which is found only in bacteria.** **Explanation:** Penicillin primarily targets the synthesis of peptidoglycan, an essential component of the bacterial cell wall. Peptidoglycan provides structural strength to bacterial cells, allowing them to maintain their shape and protect against osmotic pressure. Penicillin inhibits the enzymes responsible for cross-linking peptidoglycan chains, leading to weakened cell walls and, ultimately, bacterial cell lysis. **Key Points:** 1. **Specificity to Bacteria:** - **Peptidoglycan Presence:** Peptidoglycan is a molecule found exclusively in the cell walls of bacteria, particularly in Gram-positive bacteria. Eukaryotic cells (such as human cells) do not have peptidoglycan in their cell membranes. 2. **Mechanism of Action of Penicillin:** - **Inhibition of Cell Wall Synthesis:** By targeting the enzymes involved in peptidoglycan synthesis, penicillin disrupts the integrity of bacterial cell walls, leading to cell death. 3. **Impact on Eukaryotic Cells (Shelly's Cells):** - **No Effect:** Since eukaryotic cells lack peptidoglycan, penicillin does not interfere with their cellular structures or functions. Therefore, Shelly's eukaryotic cells remain unaffected by penicillin. **Incorrect Options Explained:** - **Disrupting the Plasma Membrane:** Penicillin does not target the plasma membrane of eukaryotic cells. - **Targeting Flagella:** Penicillin does not specifically target flagella, which are structures used for bacterial motility. - **Targeting Ribosomes:** While ribosomes are present in both prokaryotes and eukaryotes, penicillin does not target them. Antibiotics like tetracyclines and aminoglycosides are known to affect ribosomes. **Conclusion:** Penicillin's mechanism is highly specific to bacterial cells due to its targeting of peptidoglycan synthesis. Therefore, it does not impact eukaryotic cells, such as Shelly's cells. **Reference:** - **Brock Biology of Microorganisms** by Michael T. Madigan et al.