Use the following choices to answer questions 9 and 10.
1. 9 + 2 flagella
2. 70s ribosome
3. fimbria
4. nucleus
5. peptidoglycan
6. plasma membrane


Which is (are) found in all three domains?
a. 2,6
b. 5
c. 2,4,6
d. 1,3,5
e. all six

Verified step by step guidance

1. Identify the three domains of life: Bacteria, Archaea, and Eukarya.
2. Consider the cellular structures and components that are common to all three domains.
3. Recall that all cells have a plasma membrane, which is essential for maintaining the cell's environment.
4. Remember that ribosomes are present in all domains for protein synthesis, with 70S ribosomes found in both Bacteria and Archaea, and 80S in Eukarya, but 70S ribosomes are also present in mitochondria and chloroplasts of eukaryotic cells.
5. Match the options given with the components that are common to all three domains.

Key Concepts

Three Domains of Life

The Three Domains of Life—Bacteria, Archaea, and Eukarya—classify all living organisms based on genetic and biochemical differences. Bacteria and Archaea are prokaryotic, lacking a nucleus, while Eukarya includes organisms with a defined nucleus. Understanding these domains is crucial for identifying which cellular structures are universally present.

70s Ribosome

The 70s ribosome is a type of ribosome found in prokaryotic cells, consisting of a 50s and a 30s subunit. It is essential for protein synthesis and is a key feature distinguishing prokaryotes from eukaryotes, which have 80s ribosomes. Recognizing the presence of 70s ribosomes helps in understanding the cellular machinery shared among different life forms.

Peptidoglycan

Peptidoglycan is a polymer that forms a protective layer in the cell walls of bacteria, providing structural integrity. It is not found in Archaea or Eukarya, making it a distinguishing feature of bacterial cells. Understanding peptidoglycan is vital for identifying characteristics unique to the domain Bacteria.