5.7

gap junction

Structure consisting of specialized regions of the plasma membrane of two adjacent cells; contains numerous pores that allow the passage of certain small molecules and ions between them.

Cadherins

Transmembrane proteins that are components of adhering junctions between animal cells.

What is the justification for considering gap junctions and plasmodesmata to be functionally similar? How do they differ structurally?

Both plasmodesmata and gap junctions allow the movement of water, ions, and small molecules between the cytosols of neighboring cells. Gap junctions form protein-based channels between neighboring cells; plasmodesmata form continuous membrane-lined channels between the plasma membranes of neighboring cells.

Three types of cell junctions in animal cells are_____ junctions,_______ junctions_______, and junctions, while ______connect plant cells.

anchoring or tight or gap, plasmodesmata

Plasmodesmata

are channels 20 to 40 nm wide that pass through the cell walls of adjacent plant cells, connecting the cytoplasm of neighboring cells

Desmosomes

are points of attachment between cells, Buttonlike plaques, present on two opposing cell surfaces, that hold the cells together by means of protein filaments that span the intercellular space.

The________ barrier, composed of tight junctions, prevents many substances in the blood from passing into the brain

blood-brain

Gap junctions are_______ junctions between cells. Gap junctions consist of a cluster of________ , an integral membrane protein, molecules that form________ that connect the cytoplasm of adjacent cells to allow communication

communicating, connexin, cylinders

The two common types of anchoring junctions are_________ , which are anchored to intermediate filaments in the cell, and ,_______ which connect with microfilaments of the cytoskeleton.

desmosomes, adhering junctions

Most plasmodesmata contain a cylinder-shaped structure called the

desmotubule

Plasmodesmata in plant cells are functionally equivalent to______ in animal cells.

gap junctions

How are desmosomes and tight junctions functionally similar? How do they differ?

Both desmosomes and tight junctions form strong attachments between neighboring cells. Desmosomes form strong sheets of cells; tight junctions prevent passage of materials through intercellular spaces.

Tight junctions

iterally areas of tight connections between the membranes of adjacent cells, Specialized structures that form between some animal cells, producing a tight seal that prevents materials from passing through the spaces between the cells.