Answer to Question #307828 in Cell Biology for Jenwelg

Question

How do the structural distinctions between prokaryotic and eukaryotic cells reflect the varied environments in which they survive?

Answer 1

Cell Science

Every living organism falls into one of two groups: eukaryotes or prokaryotes. Cellular structure determines which group an organism belongs to. In this article, we will explain in detail what prokaryotes and eukaryotes are and outline the differences between the two.  

Prokaryote definition

Prokaryotes are unicellular organisms that lack membrane-bound structures, the most noteworthy of which is the nucleus. Prokaryotic cells tend to be small, simple cells, measuring around 0.1-5 μm in diameter.   

The key structures present in a prokaryote cell

While prokaryotic cells do not have membrane-bound structures, they do have distinct cellular regions. In prokaryotic cells, DNA bundles together in a region called the nucleoid.

Prokaryotic cell features

Here is a breakdown of what you might find in a prokaryotic bacterial cell.

• Nucleoid: A central region of the cell that contains its DNA. 
• Ribosome: Ribosomes are responsible for protein synthesis.
• Cell wall: The cell wall provides structure and protection from the outside environment. Most bacteria have a rigid cell wall made from carbohydrates and proteins called peptidoglycans.
• Cell membrane: Every prokaryote has a cell membrane, also known as the plasma membrane, that separates the cell from the outside environment.
• Capsule: Some bacteria have a layer of carbohydrates that surrounds the cell wall called the capsule. The capsule helps the bacterium attach to surfaces.
• Fimbriae: Fimbriae are thin, hair-like structures that help with cellular attachment.
• Pili: Pili are rod-shaped structures involved in multiple roles, including attachment and DNA transfer.
• Flagella: Flagella are thin, tail-like structures that assist in movement.

Examples of prokaryotes

Bacteria and archaea are the two types of prokaryotes.

Do prokaryotes have mitochondria?

No, prokaryotes do not have mitochondria. Mitochondria are only found in eukaryotic cells. This is also true of other membrane-bound structures like the nucleus and the Golgi apparatus (more on these later).

hypothesizes that mitochondria were first prokaryotic cells that lived inside Over time, evolution led to organisms functioning as a single organism in the form of a eukaryote.

Eukaryote definition

Eukaryotes are organisms whose cells have a nucleus and other organelles enclosed by a plasma membrane. Organelles are internal structures responsible for a variety of functions, such as energy production and protein synthesis.