{"id":95,"date":"2014-10-26T13:02:27","date_gmt":"2014-10-26T13:02:27","guid":{"rendered":"http:\/\/courses.candelalearning.com\/novabiology\/?post_type=chapter&p=95"},"modified":"2018-07-03T21:37:05","modified_gmt":"2018-07-03T21:37:05","slug":"comparing-prokaryotic-and-eukaryotic-cells","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/nemcc-biology1v2\/chapter\/comparing-prokaryotic-and-eukaryotic-cells\/","title":{"raw":"Comparing Prokaryotic and Eukaryotic Cells","rendered":"Comparing Prokaryotic and Eukaryotic Cells"},"content":{"raw":"
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Learning Objectives<\/h3>\r\nBy the end of this section, you will be able to:\r\n
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  • Compare and contrast prokaryotic cells and eukaryotic cells<\/li>\r\n \t
  • Describe the relative sizes of different kinds of cells<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n

    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<\/em>- = before; -karyon<\/em>- = nucleus). Animal cells, plant cells, fungi, and protists are eukaryotes (eu<\/em>- = true; -karyon- = nucleus<\/em>).<\/p>\r\n\r\n

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    Components of Prokaryotic Cells<\/h2>\r\n

    All cells share four common components:<\/p>\r\n1) a plasma membrane, an outer covering that separates the cell\u2019s interior from its surrounding environment\r\n\r\n2) cytoplasm, a jelly-like region within the cell in which other cellular components are found\r\n\r\n3) DNA, the genetic material of the cell\r\n\r\n4) ribosomes, particles that synthesize proteins, but with some differences\r\n

    <\/figure>\r\n[caption id=\"attachment_1125\" align=\"alignright\" width=\"400\"]\"In Figure 1. This figure shows the generalized structure of a prokaryotic cell.[\/caption]\r\n\r\nA prokaryotic cell is a simple, single-celled (unicellular) organism that lacks a membrane-bound nucleus, or any other membrane-bound organelle. Prokaryotic DNA is found in the central part of the cell in a darkened region called the nucleoid (Figure 1).\r\n

    Unlike Domain Archaea and eukaryotes, bacteria have a cell wall comprised of sugars and amino acids and many also have a polysaccharide capsule (Figure 1). The cell wall acts as an extra layer of protection.\u00a0 It helps the cell maintain\u00a0 shape and prevents dehydration. The capsule enables the cell to attach to environmental surfaces.\u00a0 Other structures found in bacterial cells include flagella, pili, or fimbriae. Flagella are appendages for locomotion. Pili are used to exchange genetic material during conjugation, a type of reproduction.\u00a0 Fimbriae are protein appendages used by bacteria to attach to other cells.<\/p>\r\n\r\n<\/section>

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    Eukaryotic Cells<\/h2>\r\n

    In nature, the relationship between form and function is apparent at all levels, including the cellular level.\u00a0 The principle \u201cform follows function\u201d is found throughout all life forms. \u00a0 Birds and fish have streamlined bodies that allow them to move quickly through their environment.\u00a0 Much of life is based on how something is made in order to achieve what it is made for.<\/p>\r\n

    A eukaryotic cell is a cell that has a membrane-bound nucleus and other structures.\u00a0 Organelles, \"little organs\",\u00a0 are membrane-bound compartments which have specialized functions within the cell.<\/p>\r\n\r\n<\/section>

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    Cell Size<\/h2>\r\n

    At 0.1\u20135.0 \u00b5m in diameter, prokaryotic cells are significantly smaller than eukaryotic cells, which have diameters ranging from 10\u2013100 \u00b5m (Figure 2). 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 through which materials must be transported declines.<\/p>\r\n\r\n\r\n[caption id=\"attachment_1127\" align=\"aligncenter\" width=\"1024\"]\"Relative Figure 2. This figure shows the relative sizes of different kinds of cells and cellular components. An adult human is shown for comparison.[\/caption]\r\n

    <\/figure>\r\n<\/section>
    \r\n

    Section Summary<\/h2>\r\n

    Prokaryotes are predominantly single-celled organisms of the Domains Archaea and Bacteria. \u00a0 All prokaryotes have plasma membranes, cytoplasm, DNA, and ribosomes.\u00a0 Prokaryotic cells may have other outer layers but lack membrane-bound organelles. \u00a0 Prokaryotic cells range in diameter from 0.1\u20135.0 \u00b5m.<\/p>\r\n

    Like a prokaryotic cell, a eukaryotic cell has a plasma membrane, cytoplasm, DNA and ribosomes. \u00a0 However, eukaryotic cells have a membrane-bound nucleus and other membrane-bound organelles allowing for compartmentalization of functions. Eukaryotic cells tend to be 10 to 100 times the size of prokaryotic cells.<\/p>\r\nhttps:\/\/www.openassessments.org\/assessments\/646\r\n\r\n<\/section>

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    <\/h1>\r\n \r\n
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    Additional Self Check Question<\/h3>\r\n
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    1. Describe the structures that are characteristic of a prokaryote cell.<\/p>\r\n\r\n<\/div>\r\n<\/section><\/div>\r\n<\/div>\r\n<\/section>

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    Answer<\/h3>\r\n
    \u00a01. Prokaryotic cells are surrounded by a plasma membrane and have DNA, cytoplasm, and ribosomes, like eukaryotic cells. They also have cell walls and may have a cell capsule. Prokaryotes have a single long strand of DNA that is not surrounded by a nuclear membrane. Prokaryotes may have flagella for motility, pili for conjugation, and fimbriae for adhesion to surfaces.<\/div>\r\n<\/div>\r\n \r\n\r\n<\/div>\r\n<\/section><\/div>\r\n<\/section><\/div>","rendered":"
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    Learning Objectives<\/h3>\n

    By the end of this section, you will be able to:<\/p>\n

      \n
    • Compare and contrast prokaryotic cells and eukaryotic cells<\/li>\n
    • Describe the relative sizes of different kinds of cells<\/li>\n<\/ul>\n<\/div>\n<\/div>\n

      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<\/em>– = before; –karyon<\/em>– = nucleus). Animal cells, plant cells, fungi, and protists are eukaryotes (eu<\/em>– = true; –karyon- = nucleus<\/em>).<\/p>\n

      \n

      Components of Prokaryotic Cells<\/h2>\n

      All cells share four common components:<\/p>\n

      1) a plasma membrane, an outer covering that separates the cell\u2019s interior from its surrounding environment<\/p>\n

      2) cytoplasm, a jelly-like region within the cell in which other cellular components are found<\/p>\n

      3) DNA, the genetic material of the cell<\/p>\n

      4) ribosomes, particles that synthesize proteins, but with some differences<\/p>\n

      <\/figure>\n
      \"In<\/p>\n

      Figure 1. This figure shows the generalized structure of a prokaryotic cell.<\/p>\n<\/div>\n

      A prokaryotic cell is a simple, single-celled (unicellular) organism that lacks a membrane-bound nucleus, or any other membrane-bound organelle. Prokaryotic DNA is found in the central part of the cell in a darkened region called the nucleoid (Figure 1).<\/p>\n

      Unlike Domain Archaea and eukaryotes, bacteria have a cell wall comprised of sugars and amino acids and many also have a polysaccharide capsule (Figure 1). The cell wall acts as an extra layer of protection.\u00a0 It helps the cell maintain\u00a0 shape and prevents dehydration. The capsule enables the cell to attach to environmental surfaces.\u00a0 Other structures found in bacterial cells include flagella, pili, or fimbriae. Flagella are appendages for locomotion. Pili are used to exchange genetic material during conjugation, a type of reproduction.\u00a0 Fimbriae are protein appendages used by bacteria to attach to other cells.<\/p>\n<\/section>\n

      \n

      Eukaryotic Cells<\/h2>\n

      In nature, the relationship between form and function is apparent at all levels, including the cellular level.\u00a0 The principle \u201cform follows function\u201d is found throughout all life forms. \u00a0 Birds and fish have streamlined bodies that allow them to move quickly through their environment.\u00a0 Much of life is based on how something is made in order to achieve what it is made for.<\/p>\n

      A eukaryotic cell is a cell that has a membrane-bound nucleus and other structures.\u00a0 Organelles, “little organs”,\u00a0 are membrane-bound compartments which have specialized functions within the cell.<\/p>\n<\/section>\n

      \n

      Cell Size<\/h2>\n

      At 0.1\u20135.0 \u00b5m in diameter, prokaryotic cells are significantly smaller than eukaryotic cells, which have diameters ranging from 10\u2013100 \u00b5m (Figure 2). 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 through which materials must be transported declines.<\/p>\n

      \"Relative<\/p>\n

      Figure 2. This figure shows the relative sizes of different kinds of cells and cellular components. An adult human is shown for comparison.<\/p>\n<\/div>\n

      <\/figure>\n<\/section>\n
      \n

      Section Summary<\/h2>\n

      Prokaryotes are predominantly single-celled organisms of the Domains Archaea and Bacteria. \u00a0 All prokaryotes have plasma membranes, cytoplasm, DNA, and ribosomes.\u00a0 Prokaryotic cells may have other outer layers but lack membrane-bound organelles. \u00a0 Prokaryotic cells range in diameter from 0.1\u20135.0 \u00b5m.<\/p>\n

      Like a prokaryotic cell, a eukaryotic cell has a plasma membrane, cytoplasm, DNA and ribosomes. \u00a0 However, eukaryotic cells have a membrane-bound nucleus and other membrane-bound organelles allowing for compartmentalization of functions. Eukaryotic cells tend to be 10 to 100 times the size of prokaryotic cells.<\/p>\n