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What are the two main types of cell-cell adhesive junctions in vertebrates, and how do their attachments to the cytoskeleton differ? What advantages might there be for these junctions to be attached to the cytoskeleton?
To determine: The two main types of cell-cell adhesive junctions in vertebrates and how do their attachments to the cytoskeleton differ.
Introduction: The organization of multi-cellular organisms is best understood on understanding the connection between cells, or in other words, cell-cell adhesions. Junctions are used by the cells to attach to one another. Transmembrane proteins are used to link the cell surface to the cytoskeleton. Extracellular matrix plays an important role in cell-cell adhesion and cell-cell communication.
Explanation of Solution
Linkage of cells together to form tissue is done with the help of adhesive junctions.
The two main types of cell-cell adhesive junctions are as follows:
- Adherens junctions:
They participate in cell-cell attachment and are prominent in epithelial cells. Cadherins are the transmembrane proteins which help the adherens junctions to attach two adjacent cells together.
- Desmosome:
They participate in cell-cell attachment and are found in tissues experiencing mechanical stress such as heart muscle, and the uterus. The main purpose of desmosomes is to provide structural support to the tissues so that they can bear the mechanical stress.
The main difference between the methods of attachment between the adherens junctions and the desmosomes is that adherens junctions form continuous zones of attachment, whereas desmosomes form localized points of attachment. The continuous zone of attachment formed by the adherens junctions encircles the cell near the apical end of the lateral membrane. Desmosomes on the other hand act as button-like points joining two adjacent cells together.
To explain: The advantages of adhesive junctions to be attached to the cytoskeleton.
Introduction: The organization of multi-cellular organisms is best understood on understanding the connection between cells, or in other words, cell-cell adhesions. Junctions are used by the cells to attach to one another. Transmembrane proteins are used to link the cell surface to the cytoskeleton. Extracellular matrix plays an important role in cell-cell adhesion and cell-cell communication
Explanation of Solution
Adhesive junctions link the cells together and help them in forming a tissue. Linker proteins attach the transmembrane adhesion proteins such as cadherins to the cytoskeleton.
The advantage of attaching adhesive junction to the cytoskeleton is as follows:
- Desmosomes are a type of adhesive junction and these protect the cell from the mechanical stress experienced by the tissues such as heart tissue, and uterus. The cell reacts to mechanical stress by communicating with each other through these junctions.
Therefore, in order to react to the mechanical stress and orient the cytoskeleton accordingly adhesive junctions are attached to the cytoskeleton.
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Chapter 15 Solutions
Becker's World of the Cell (9th Edition)
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