Prokaryotic cell traits: identify the statement that is NOT true Which of the following statements does NOT correctly describe prokaryotic organisms (bacteria or archaea)?

Introduction / Context:
Prokaryotes exhibit hallmark differences from eukaryotes in cellular organization, genome structure, and protein synthesis machinery. Identifying false statements about prokaryotes is a common test of foundational microbiology knowledge. The ribosome size is a particularly important discriminator in pharmacology and diagnostics.

Given Data / Assumptions:

• Prokaryotes lack a true nucleus and membrane-bound organelles.
• Bacterial cell walls contain peptidoglycan; archaeal walls lack peptidoglycan.
• Ribosome sedimentation coefficients differ between prokaryotes and eukaryotes.

Concept / Approach:

Prokaryotic ribosomes are 70S, composed of 50S and 30S subunits. Eukaryotic cytosolic ribosomes are 80S (60S + 40S). Therefore, any statement placing 80S ribosomes in the prokaryotic cytoplasm is false. Other statements align with standard descriptions: absence of a nuclear membrane, limited or absent histones in bacteria (some archaea possess histone-like proteins), and peptidoglycan in bacterial cell walls.

Step-by-Step Solution:

Verification / Alternative check:

Antibiotics such as tetracyclines target 30S subunits, exploiting the 70S ribosome difference to achieve selective toxicity against bacteria.

Why Other Options Are Wrong (i.e., they are true):

• No nuclear membrane: true for prokaryotes.
• Chromosomes without canonical eukaryotic histones: true for bacteria; some archaea have histone-like proteins, but overall the statement holds as written.
• Peptidoglycan in bacterial walls: true, though absent in archaea.
• Single circular chromosome: typical of bacteria, with exceptions.

Common Pitfalls:

• Confusing 70S vs 80S, especially when considering mitochondrial/chloroplast 70S ribosomes inside eukaryotes.
• Assuming all prokaryotes share identical wall chemistry; archaea are different.

Final Answer:

80S ribosomes are distributed in the cytoplasm.