Which lab procedure is the best to use to determine whether a newly discovered single-celled organism is prokaryotic or eukaryotic?
A) Search for the presence of membrane-bound structures within the cell, using transmission electron microscopy.
B) Determine the molecular makeup of the organism's cell membrane, using chemical analysis.
C) Stain cells with a ribosome-specific stain, and then use light microscopy to assess whether ribosomes are present or absent in the cells.
D) Use biochemical methods to determine whether the organism has a cell wall and is also capable of carrying out photosynthesis.
E) Use analytical techniques to determine the number of genes encoded in the organism's DNA.

Question

Quizplus · Accepted Answer

The presence or absence of membrane-bound structures is the main differentiating factor between prokaryotic and eukaryotic cells. Transmission electron microscopy allows for visualization of these structures at a high resolution, making it the best lab procedure to determine the type of cell. Chemical analysis of the cell membrane (B) does not necessarily indicate whether the cell is prokaryotic or eukaryotic. Staining cells for ribosomes (C) can indicate whether the cells have ribosomes, but this does not distinguish between prokaryotic and eukaryotic cells since both have ribosomes. Biochemical methods for determining cell wall composition (D) and the ability to carry out photosynthesis also do not definitively differentiate between prokaryotes and eukaryotes. Analyzing the number of genes encoded in the DNA (E) can provide information on the complexity of the organism, but does not necessarily determine whether it is prokaryotic or eukaryotic.

Which Lab Procedure Is the Best to Use to Determine