Comparison of Prokaryotic and Eukaryotic Cells

Many scientists believe that almost 2.7 billion years ago, the second group of cells called eukaryotic cells formed from the pre-existing prokaryotic cells. To this day, cells are divided into two distinct groups based on if the cell contains a nucleus and if the organelles are coated with the membrane material. Even though the prokaryotic cells were the first form of life, eukaryotic cells are much more complex and have more features than prokaryotic cells. 

All cells are divided into two broad categories: prokaryotic and eukaryotic based on if a nucleus is present and if the organelles are membrane-bound. Prokaryotic cells are the simple, unicellular cells that lack a nucleus and lack the membrane covering the cell’s organelles. With an average of 0.1 to 0.5 micrometers in diameter, prokaryotic cells are much smaller in size compared to eukaryotic cells. Since prokaryotic cells are unicellular and much more compact, prokaryotic cells lack many of the organelles eukaryotic cells contain, such as the nucleus, lysosomes, peroxisomes, microtubules, ER, vacuoles, and vesicles. Although prokaryotic cells do lack many organelles, prokaryotic cells still consist of nucleoids, ribosomes, a cell wall, a cell membrane, flagella, capsules, fimbriae, and pili. The nucleoid region is located in the middle of the prokaryotic cell which contains the DNA and scattered chloroplasts. Bacteria cells have a cell wall made of sugars, amino acids, and sometimes a polysaccharide capsule. Prokaryotic cells still have a cell wall to provide extra protection and prevent dehydration. The large carbohydrate layer that surrounds the cell wall is called the capsule, and since the capsule is made up of polysaccharides and sugar polymers the cell can cling to the surrounding environment. The flagella are the small hair-like structures located at the tip of the prokaryotic cell that are responsible for the movement of the cell, and pili are used to exchange genetic material during conjugation. Although prokaryotic cells go through the process of conjugation, prokaryotic cells do not go through processes such as endocytosis and exocytosis. Since prokaryotic cells lack a selectively permeable membrane, endocytosis and exocytosis are not needed. Due to the chlorophyll being scattered around the cell membrane, the DNA is bundled together in the nucleoid region which leads to extremely compact genomes. In prokaryotic cells, a sequence of DNA with a cluster of genes known as operons form, but in eukaryotic cells each gene is made on mRNA strands. 

The second group of cells are called eukaryotic cells. Eukaryotes cells are the cells that contain membrane-bound organelles and have a nucleus. The most popular examples of eukaryotic cells are plants, fungi, and animals. Unlike prokaryotic cells, eukaryotic cells contain a nucleus, lysosomes, peroxisomes, microtubules, an endoplasmic reticulum, mitochondria, cytoskeleton, a golgi apparatus, chloroplasts, vesicles, and vacuoles. Most eukaryotic cells contain all of the organelles listed above, but not all eukaryotic cells contain a Golgi apparatus, chloroplasts, and lysosomes. The main difference between eukaryotic and prokaryotic cells is the difference in the nucleoid region. In eukaryotic cells, there is a smaller circular organelle, called the nucleolus, which produces RNA for the cell. Compared to prokaryotic cells, the ribosomes found in the eukaryotic cells are much larger in size. With a diameter of around 10 to 100 micrometer, these multicellular cells have more space to hold organelles prokaryotic cells can not hold. Eukaryotic cells also have a selectively permeable membrane, which means only certain substances can enter and exit through the cell membrane. The cell wall and cell membrane’s purpose is to protect the cell and all of the organelles in the correct place. Another membrane called the plasma membrane is the phospholipid bilayer that surrounds the eukaryotic cell along with all of the organelles inside the cell. The eukaryotic cell is filled with the cytoplasm or the gel-like substance that fills the cell, which is made up of cytosol. Another important organelle is the mitochondria, also known as the powerhouse of the cell, which is responsible for energy production, and the ribosomes help with processes such as protein synthesis. The endoplasmic reticulum works with those ribosomes to help with protein maturation and protein transportation. The last organelles are the vacuoles and vesicles which are the sacs that store the extra waste from the cell.

Even though eukaryotic cells and prokaryotic cells are two completely different groups, both types of cells contain some similarities. For example, both eukaryotic and prokaryotic cells have vacuoles to hold the broken organelles parts, waste, food, and water. Both cells also have ribosomes, but the ribosomes found in the eukaryotic cells are much larger in size compared to the ribosomes in the prokaryotic cell. Both eukaryotic cells and prokaryotic cells have DNA, also known as deoxyribonucleic acid, a plasma membrane and a cytoplasm. Both types of cells go through the basic functions of life: evolution, cellular organization, growth, heredity, homeostasis, reproduction, metabolism, and a response to stimuli. Even though prokaryotic and eukaryotic cells may complete these processes differently, at the end of the day both types of cells must go through these processes to have a healthy cell. Along with both cells having DNA, prokaryotic and eukaryotic cells also both have rDNa, or ribosomal DNA, which is needed to go through the many processes listed above.

In conclusion, prokaryotic cells are the single-celled organisms without a nucleus and membrane bound organelles. Although prokaryotic cells lack many organelles eukaryotic cells have, both types of cells contain DNA, rDNA, plasma membranes, cytoplasms, ribosomes, cell walls, and go through similar cellular processes. Similar to the prokaryotic cell, eukaryotic cells also have a plasma membrane, cytoplasm, ribosomes, along with the many organelles prokaryotic cells lack. Since eukaryotic cells have more complex organelles overall, the eukaryotic cells are much larger and advanced than the prokaryotic cells. Eukaryotic cells are the only type of cells that have a “true nucleus” and membrane bound organelles, which sets eukaryotic cells apart from prokaryotic cells.