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All About Animal Cells

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All About Animal Cells
Animal Cell

Animal Cell

Public Domain Image: National Human Genome Research Institute

 

All About Animal Cells

Animal cells are eukaryotic cells, or cells with a membrane-bound nucleus. Unlike prokaryotic cells, DNA in animal cells is housed within the nucleus. In addition to having a nucleus, animal cells also contain other membrane-bound organelles, or tiny cellular structures, that carry out specific functions necessary for normal cellular operation. Organelles have a wide range of responsibilities that include everything from producing hormones and enzymes to providing energy for animal cells.

Animal Cells vs Plant Cells

Animal cells are similar to plant cells in that they are both eukaryotic cells and have similar organelles. Animal cells are generally smaller than plant cells. While animal cells come in various sizes and tend to have irregular shapes, plant cells are more similar in size and are typically rectangular or cube shaped. A plant cell also contains structures not found in an animal cell. Some of these include a cell wall, a large vacuole, and plastids. Plastids, such as chloroplasts, assist in storing and harvesting needed substances for the plant. Animal cells also contain structures such as centrioles, lysosomes, cilia, and flagella that are not typically found in plant cells.

Animal Cells: Organelles and Components

The following are examples of structures and organelles that can be found in typical animal cells:

  • Cell (Plasma) Membrane - thin, semi-permeable membrane that surrounds the cytoplasm of a cell, enclosing its contents.

  • Centrioles - cylindrical structures that organize the assembly of microtubules during cell division.

  • Cytoplasm - gel-like substance within the cell.

  • Endoplasmic Reticulum - extensive network of membranes composed of both regions with ribosomes (rough ER) and regions without ribosomes (smooth ER).

  • Golgi Complex - also called the Golgi apparatus, this structure is responsible for manufacturing, storing and shipping certain cellular products.

  • Lysosomes - sacs of enzymes that digest cellular macromolecules such as nucleic acids.

  • Microtubules - hollow rods that function primarily to help support and shape the cell.

  • Mitochondria - cell components that generate energy for the cell and are the sites of cellular respiration.

  • Nucleus - membrane bound structure that contains the cell's hereditary information.
    • Nucleolus - structure within the nucleus that helps in the synthesis of ribosomes.
    • Nucleopore - tiny hole within the nuclear membrane that allows nucleic acids and proteins to move into and out of the nucleus.
  • Ribosomes - consisting of RNA and proteins, ribosomes are responsible for protein assembly.


Animal cells contain other cell structures that are not depicted in the illustration above. Some of these structures include:

  • Cytoskeleton - network of fibers throughout the cell's cytoplasm that gives the cell support and helps to maintain its shape.

  • Cilia and flagella - specialized groupings of microtubules that protrude from some cells and aid in cellular locomotion.

  • Peroxisomes - enzyme containing structures that help to detoxify alcohol, form bile acid, and break down fats.

Animal Cell Structure

Animal organisms can be composed of trillions of cells. These cells come in all shapes and sizes and their structure suits their function. For example, the body's nerve cells or neurons have a vastly different shape and function than red blood cells. Nerve cells transport electrical signals throughout the nervous system. They are elongated and thin, with projections that extend out to communicate with other nerve cells in order to conduct and transmit nerve impulses. The major role of red blood cells is to transport oxygen to body cells. Their small, flexible disc shape enables them to maneuver through tiny blood vessels to deliver oxygen to organs and tissues.
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