Question

Which of these do all prokaryotes and eukaryotes share? a. nuclear envelope b. cell walls c. organelles d. plasma membrane

Short answer

The common feature shared by all prokaryotes and eukaryotes is the plasma membrane (option d).

Step-by-step solution

Understanding Prokaryotic and Eukaryotic Cells

Prokaryotic cells are generally smaller and simpler in structure compared to eukaryotic cells. They lack a nucleus and any membrane-bound organelles. Bacteria and archaea are examples of prokaryotes. Eukaryotic cells are usually larger and contain a nucleus, which is surrounded by a nuclear envelope. In addition, they possess various membrane-bound organelles, such as mitochondria, endoplasmic reticulum, and golgi apparatus. Examples of eukaryotic cells include plant, animal, and fungal cells.

Evaluate Option (a): Nuclear Envelope

A nuclear envelope is present in eukaryotic cells, but not in prokaryotic cells. Therefore, this option is not the correct answer.

Evaluate Option (b): Cell Walls

While most prokaryotic cells have cell walls, not all eukaryotic cells have them. For example, animal cells do not have cell walls. So, this option is also not the correct answer.

Evaluate Option (c): Organelles

Although eukaryotic cells contain membrane-bound organelles, prokaryotic cells do not have them. Therefore, this option is not correct as well.

Evaluate Option (d): Plasma Membrane

All cells, both prokaryotic and eukaryotic, have a plasma membrane which serves as a protective barrier and regulates the exchange of substances between the cell and its environment. Therefore, the correct answer is option (d).

Conclusion

The common feature shared by all prokaryotes and eukaryotes is the plasma membrane (option d).

Key concepts

Prokaryotic Cells

Prokaryotic cells are the simplest form of life. They are primarily known for lacking a defined nucleus and membrane-bound organelles.
Prokaryotic cells are generally smaller in size. This simplicity is accompanied by efficient functionality in various environments, such as hot springs or deep ocean vents. This is why you often find prokaryotes, like bacteria and archaea, in extreme conditions.
While they may not have organelles like mitochondria, prokaryotic cells perform all necessary life functions, thanks to their specialized cellular structures. For instance:

• Their genetic material is located in a region called the nucleoid.
• They have ribosomes for protein synthesis.
• Some possess flagella or pili that aid in movement or adherence to surfaces.

These unique features enable prokaryotic cells to thrive and reproduce in diverse environments.

Eukaryotic Cells

Eukaryotic cells are more complex with a greater number of structures that perform specific functions. The presence of a nucleus, surrounded by a nuclear envelope, is their defining characteristic.
This type of cell forms the make-up of plants, animals, and fungi. These cells are also usually larger in size than prokaryotic cells.
Key features of eukaryotic cells include:

• Organelles like mitochondria, which provide energy through cellular respiration.
• Endoplasmic reticulum and Golgi apparatus, involved in protein and lipid synthesis.
• A cytoskeleton that supports the cell's structure.

The complexity of eukaryotic cells allows them to carry out more intricate processes. This specialization is vital for the survival and functionality of multicellular organisms.

Plasma Membrane

The plasma membrane is a crucial component of both prokaryotic and eukaryotic cells. It acts as a barrier, maintaining the integrity of the interior of the cell.
Composed primarily of a lipid bilayer, the plasma membrane ensures a selective barrier function. It allows the passage of essential substances like nutrients and gases while preventing harmful materials from entering the cell.
Key roles of the plasma membrane include:

• Maintaining homeostasis by regulating what enters and leaves the cell.
• Facilitating communication through receptor proteins that receive signals.
• Enabling some cells to move or change shape due to its flexible structure.

The plasma membrane's adaptability and functionality underscore its importance in cellular life. Regardless of whether a cell is prokaryotic or eukaryotic, the plasma membrane is indispensable for survival. This shared feature highlights the fundamental similarities between the two cell types, despite their differences.