Can water pass through tight junctions?
Tight junctions may also serve as leaky pathways by forming selective channels for small cations, anions, or water. Tight junctions are present mostly in vertebrates (with the exception of Tunicates).
Which type of junctions allows small molecules to pass between cells?
Gap junctions are specialized connections that form a narrow pore between adjacent cells. These pores permit small molecules and ions to move from one cell to another. In this way, gap junctions provide metabolic and electrical coupling between cells.
Does connective tissue have tight junctions?
Junctions between cells or with connective tissue can have additional functions other than adhesion. A tight junction that forms a zone or belt around the entire cell, joining it with each of the adjacent cells is called a zonula occludens (ZO) (Figure 1-5).
What is the purpose of tight junctions?
Tight junctions form the continuous intercellular barrier between epithelial cells, which is required to separate tissue spaces and regulate selective movement of solutes across the epithelium.
Do all cells have tight junctions?
Tight junctions are often found at epithelial cells, which are cells that line the surface of the body and line body cavities. Not only do epithelial cells separate the body from the surrounding environment, they also separate surfaces within the body.
Where are gap junctions not found?
Gap junctions occur in virtually all tissues of the body, with the exception of adult fully developed skeletal muscle and mobile cell types such as sperm or erythrocytes. Gap junctions, however, are not found in simpler organisms such as sponges and slime molds.
What type of cell membrane protein enables neighboring cells to stick to each other?
Tight junctions hold cells completely flat against each other, with proteins extending from one plasma membrane into the other. Communication is possible between some of these connections.
Which cell shape is the most efficient exchange of materials?
(B) Cell shape 2 because it has the largest surface area per unit of volume. Rationale: This answer suggests the student understands that the indentation in a disc-shaped object increases the surface area-to-volume ratio, which results in increased efficiency of nutrient exchange.