What are the 3 major differences between prokaryotic and eukaryotic cells?
|
Cells fall into one of two broad categories: prokaryotic and eukaryotic. The predominantly single-celled organisms of the domains Bacteria and Archaea are classified as prokaryotes (pro– = before; –karyon– = nucleus). Animal cells, plant cells, fungi, and protists are eukaryotes (eu– = true). Show
All cells share four common components: 1) a plasma membrane, an outer covering that separates the cell’s interior from its surrounding environment; 2) cytoplasm, consisting of a jelly-like region within the cell in which other cellular components are found; 3) DNA, the genetic material of the cell; and 4) ribosomes, particles that synthesize proteins. However, prokaryotes differ from eukaryotic cells in several ways. A prokaryotic cell is a simple, single-celled (unicellular) organism that lacks a nucleus, or any other membrane-bound organelle. We will shortly come to see that this is significantly different in eukaryotes. Prokaryotic DNA is found in the central part of the cell: a darkened region called the nucleoid. Figure 3.6 This figure shows the generalized structure of a prokaryotic cell.Unlike Archaea and eukaryotes, bacteria have a cell wall made of peptidoglycan, comprised of sugars and amino acids, and many have a polysaccharide capsule (Figure 3.6). The cell wall acts as an extra layer of protection, helps the cell maintain its shape, and prevents dehydration. The capsule enables the cell to attach to surfaces in its environment. Some prokaryotes have flagella, pili, or fimbriae. Flagella are used for locomotion, while most pili are used to exchange genetic material during a type of reproduction called conjugation. In nature, the relationship between form and function is apparent at all levels, including the level of the cell, and this will become clear as we explore eukaryotic cells. The principle “form follows function” is found in many contexts. For example, birds and fish have streamlined bodies that allow them to move quickly through the medium in which they live, be it air or water. It means that, in general, one can deduce the function of a structure by looking at its form, because the two are matched. A eukaryotic cell is a cell that has a membrane-bound nucleus and other membrane-bound compartments or sacs, called organelles, which have specialized functions. The word eukaryotic means “true kernel” or “true nucleus,” alluding to the presence of the membrane-bound nucleus in these cells. The word “organelle” means “little organ,” and, as already mentioned, organelles have specialized cellular functions, just as the organs of your body have specialized functions. At 0.1–5.0 µm in diameter, prokaryotic cells are significantly smaller than eukaryotic cells, which have diameters ranging from 10–100 µm (Figure 3.7). The small size of prokaryotes allows ions and organic molecules that enter them to quickly spread to other parts of the cell. Similarly, any wastes produced within a prokaryotic cell can quickly move out. However, larger eukaryotic cells have evolved different structural adaptations to enhance cellular transport. Indeed, the large size of these cells would not be possible without these adaptations. In general, cell size is limited because volume increases much more quickly than does cell surface area. As a cell becomes larger, it becomes more and more difficult for the cell to acquire sufficient materials to support the processes inside the cell, because the relative size of the surface area across which materials must be transported declines. Figure 3.7 This figure shows the relative sizes of different kinds of cells and cellular components. An adult human is shown for comparison.Prokaryotes are predominantly single-celled organisms of the domains Bacteria and Archaea. All prokaryotes have plasma membranes, cytoplasm, ribosomes, a cell wall, DNA, and lack membrane-bound organelles. Many also have polysaccharide capsules. Prokaryotic cells range in diameter from 0.1–5.0 µm. Like a prokaryotic cell, a eukaryotic cell has a plasma membrane, cytoplasm, and ribosomes, but a eukaryotic cell is typically larger than a prokaryotic cell, has a true nucleus (meaning its DNA is surrounded by a membrane), and has other membrane-bound organelles that allow for compartmentalization of functions. Eukaryotic cells tend to be 10 to 100 times the size of prokaryotic cells. eukaryotic cell: a cell that has a membrane-bound nucleus and several other membrane-bound compartments or sacs Eukaryotic cells contain a nucleus and organelles bound by plasma membranes. Fungi, plants, and animals are made of eukaryotic cells (eukaryotes). Prokaryotic cells do not have a membrane-bound nucleus or organelles. All bacteria and members of Archaea are made of prokaryotic cells (prokaryotes).  Table of Contents[hide][show]Difference Between Eukaryotic And Prokaryotic CellsThe most obvious difference between them is that prokaryotes have no nuclei, but there are four major differences between a eukaryotic and prokaryotic cell:
For all their differences, prokaryotes and eukaryotes have a few similarities share some common structures (due to physics and evolution), and though their DNA is different, they even share some genetic features. Both types of cells have five similarities:
Structures Found In Prokaryotic And Eukaryotic CellsAll living organisms use cellular organization to create structures to conduct life processes. Cells organize into tissues, which organize into organs, which organize into amazing life forms like plants, fungi, dogs, ducks, and people. Intracellular structures are common to both types of cells. Both prokaryotic and eukaryotic cells have:
ProkaryotesAn organism with prokaryotic cells is a prokaryote. Prokaryotic organisms get their names from the Greek roots, pro (before) and karyon (nut or kernel). This roughly means they are cells with structures so simple that they came from a time before a cell's nucleus existed. The three domains of life, Eukaryota, Bacteria, and Archaea, include two branches that are prokaryotes:
Only the domain, Eukaryota, has eukaryotic cells. Examples of archaea include Crenarchaeota (living in extreme acidity or temperatures) and Euryarchaeota (living in salty water or producing methane). Prokaryotic CellsProkaryotic cells are extremely small, much smaller than eukaryotic cells. A typical prokaryotic cell is of a size ranging from 0.1 microns (mycoplasma bacteria) to 5.0 microns. 1 micron or micrometer, μm, is one-thousandth of a millimeter or one-millionth of a meter. Anywhere from 200 to 10,000 prokaryotic cells could fit on the head of a pin. Their small size makes prokaryotic cells just one half to one-thousandth the size of a eukaryotic cell, which is typically between 10 and 100 μm. One amazing prokaryotic outlier is Thiomargarita namibiensis, the largest bacterium ever discovered, coming in at a whopping 100 to 300 μm. That is large enough to see in a light microscope. Prokaryotic OrganellesProkaryotes have no organelles in their cells! All the equivalent functions of eukaryotic cells are performed by four structures: a plasma membrane, cytoplasm, ribosomes, and genetic material (both rDNA and DNA). Facts About Prokaryotic Cells
EukaryotesFungi, plants, protista, and all animals (including humans) are eukaryotes. We are all built with eukaryotic cells. The word eukaryote comes from two Greek roots, eu (good, well), and karyon (nut, kernel), so a eukaryote has a well-defined or “good” nucleus (kernel) in its cells. Eukaryotes CellsEukaryotic cells have nuclei and organelles, which immediately sets them apart from prokaryotic cells. The organelles in eukaryotic cells act as tiny membrane-bound compartments performing all the functions of life in the cell: energy acquisition and transfer, digestion, waste management, reproduction, and cellular respiration. Some of these eukaryotic cell organelles are:
Size Of Eukaryotic CellsIn general, eukaryotic cells are much bigger than prokaryotic cells. One eukaryotic cell could be double to 1,000 times the size of a prokaryotic cell. Eukaryotic cells measure between 10 µm and 100 µm, which means you could barely see them with a standard school light microscope. What are the 3 similarities and 3 differences between prokaryotic and eukaryotic cells?Like a prokaryotic cell, a eukaryotic cell has a plasma membrane, cytoplasm, and ribosomes, but a eukaryotic cell is typically larger than a prokaryotic cell, has a true nucleus (meaning its DNA is surrounded by a membrane), and has other membrane-bound organelles that allow for compartmentalization of functions.
What are 5 differences between prokaryotic and eukaryotic cells?Thus, two types of cells are found in the organisms: eukaryotic and prokaryotic depending on whether cells contain membrane-bound organelles or not.
...
What is the difference between Prokaryotic and Eukaryotic Cells?. What are 4 differences between prokaryotic and eukaryotic cells?Eukaryotic cells contain membrane-bound organelles, such as the nucleus, while prokaryotic cells do not. Differences in cellular structure of prokaryotes and eukaryotes include the presence of mitochondria and chloroplasts, the cell wall, and the structure of chromosomal DNA.
What is the main difference between eukaryotes and prokaryotes?One of the main differences between prokaryotes and eukaryotes is their DNA structure. As stated above, in a prokaryotic cell, genomic DNA is present in the central nucleoid region and is not membrane-bound. However, in eukaryotes, the genetic material is present in the nucleus, a membrane-bound cell organelle.
|
