which one of the following is never found in prokaryotic cells?
Which one of the following is never found in prokaryotic cells?
Answer:
In order to determine what is never found in prokaryotic cells, it’s essential to understand the structure and characteristics of these cells. Prokaryotic cells, which include bacteria and archaea, are simpler and smaller than eukaryotic cells and lack certain organelles and structures found in eukaryotes.
Characteristics of Prokaryotic Cells:
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Nucleoid Region:
- Prokaryotic cells have a nucleoid region where their genetic material (DNA) is located, but it is not enclosed within a membrane.
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Ribosomes:
- Ribosomes are present in prokaryotic cells and are necessary for protein synthesis. However, prokaryotic ribosomes are smaller (70S) compared to eukaryotic ribosomes (80S).
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Cell Wall:
- Most prokaryotes have a cell wall that provides structure and protection. In bacteria, this is typically made of peptidoglycan.
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Plasma Membrane:
- The plasma membrane controls the movement of substances in and out of the cell.
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Cytoplasm:
- The cytoplasm is where metabolic processes occur, and it contains the cell’s ribosomes and various inclusions.
Structures Never Found in Prokaryotic Cells:
Considering the typical structures within a prokaryotic cell, the following are never found:
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Membrane-bound Organelles:
- Prokaryotic cells do not have membrane-bound organelles such as mitochondria, endoplasmic reticulum (ER), Golgi apparatus, and lysosomes.
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Nucleus:
- Prokaryotic cells do not have a true nucleus. Their DNA is not enclosed within a nuclear membrane.
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Mitochondria:
- Mitochondria are the powerhouse of the cell and are found only in eukaryotic cells. Prokaryotes generate energy through processes like cellular respiration across the plasma membrane.
Final Answer:
Based on the above analysis, the structure that is never found in prokaryotic cells is the nucleus.
Therefore, the correct answer is:
The nucleus is never found in prokaryotic cells.