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Different Kinds of Cell

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Different Kinds of Cell

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Different Types of CellsThere are two main groups of cells, prokaryotic and eukaryotic cells. They differ not only in their appearance but also in their structure, reproduction, and metabolism. However, all of the cells belong to one of the five life kingdoms. The greatest difference lies between cells of different kingdoms. The following diagram shows the five kingdoms: monera, protista, plantae, fungi, and animalia.  Copyright Daniel KunkelThe cells in the 5 kingdoms can all be classified as either prokaryotic or eukaryotic. Click below to learn about the two types of cells.|

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Prokaryotic CellsCells that lack a membrane-bound nucleus are called prokaryotes (from the Greek meaning before nuclei). These cells have few internal structures that are distinguishable under a microscope. Cells in the monera kingdom such as bacteria and cyanobacteria (also known as blue-green algae) are prokaryotes.Prokaryotic cells differ significantly from eukaryotic cells. They don't have a membrane-bound nucleus and instead of having chromosomal DNA, their genetic information is in a circular loop called a plasmid. Bacterial cells are very small, roughly the size of an animal mitochondrion (about 1-2µm in diameter and 10 µm long). Prokaryotic cells feature three major shapes: rod shaped, spherical, and spiral. Instead of going through elaborate replication processes like eukaryotes, bacterial cells divide by binary fission.Diagram of a prokaryotic cell. Notice the internal organelles are not easily distinguishable.Bacteria perform many important functions on earth. They serve as decomposers, agents of fermentation, and play an important role in our own digestive system. Also, bacteria are involved in many nutrient cycles such as the nitrogen cycle, which restores nitrate into the soil for plants. Unlike eukaryotic cells that depend on oxygen for their metabolism, prokaryotic cells enjoy a diverse array of metabolic functions. For example, some bacteria use sulfur...

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