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Types of Cell Junctions

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  • 0:01 Dealing with Neighbors
  • 0:32 Plasmodesmata
  • 1:23 Gap Junctions
  • 2:07 Desmosome & Tight Junctions
  • 3:29 Memory Aid
  • 4:00 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov
How do cells deal with neighboring cells? Do they communicate with one another or hold hands? This lesson explores the world of animal and plant cell junctions.

Dealing with Neighbors

How do you deal with your neighbors? Do you have a nice, open channel of communication? Are you strongly bonded together? Do you try to keep yourselves apart by blocking each other's view?

Neighboring plant and animal cells must also interact in one way or another. Sometimes they have open channels of communication, and other times they simply hold each other tightly. Aw, how sweet! This lesson covers four kinds of cell junctions. One is found in plants and three are found in animal tissues.

Plasmodesmata

Plant cell walls contain something known as plasmodesmata (plural for plasmodesma), which are narrow, membrane-lined microscopic channels that span plant cell walls. The word comes from the Greek for bond: desmos.

Think of these channels as simply tunnels or bridges between neighboring plant cells. What do tunnels and bridges do for us humans? They facilitate the flow of information and material between two points, as trucks transport goods and mail when traveling through them. Of course, plant cells don't have trucks and don't have mail. Instead, we know that plasmodesmata allow for the passage of the following between plant cells:

  • Water
  • Nutrients
  • Signaling molecules
  • In some cases, some proteins and even RNA molecules, with the latter being a piece of genetic code.

Gap Junctions

The closest animal tissue equivalents to plasmodesmata are gap junctions. A gap junction, also called macula communicans and communicating junction, is an intercellular junction found in animal tissues that allows for physiological components to pass from cell to cell. Gap junctions are cylinders made of membrane proteins that form a pore between two cells. Inasmuch, a gap junction directly connects the cytoplasm of two cells. And so, just like plasmodesmata, these gap junctions are like tunnels that allow for ions, amino acids, sugar, and other small molecules to pass from one cell to another.

Desmosomes & Tight Junctions

While plasmodesmata and gap junctions allow for communication and continuity between cells, there are animal tissue junctions that are used for cell-to-cell adhesion, as opposed to communication. Have you ever seen rivets fastening two pieces of metal together, causing them to tightly adhere to one another? These rivets are like a desmosome, also called macula adherens or anchoring junction, which are localized spot-welds, which function to maintain adhesion between adjacent cells.

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