Exam 7: Interactions Between Cells and Their Environment

Lymphocytes are isolated and labeled with radioactive isotopes.They are then exposed to frozen tissue sections of a lymphoid organ.What happens?

What forms the barrier of the tight junctions that seals off the space between adjacent cells?

You are studying a plant and inject fluorescein,a fluorescent dye,into a single cell on the surface of the plant.After a brief period of time,the dye spreads to cells neighboring the injected cell.What do you conclude?

Which tissues below are typically derived from the cells on the dorsal surface of a mammalian embryo after gastrulation that express N-cadherins and stop expressing E-cadherins?

If extracellular matrix materials are added back to the cells described in question #2,what happens?

In which disease do individuals produce antibodies that bind to proteins present in hemidesmosmes? It causes the lower layer of the epidermis to lose attachment to the underlying basement membrane and thus to the underlying connective tissue layer of the dermis.The leakage of fluid into the space beneath the epidermis results in severe blistering of the skin.

What type of cell adhesion molecule is associated with cells being held together by adherens junctions at the site of the junction?

Attachment of an integrin to its ligand can induce which of the following responses within a cell?

You are investigating the interactions of integrin $\alpha$ and $\beta$ subunits and isolate the extracellular portion of an integrin as a soluble $\alpha$ / $\beta$ heterodimer.The heterodimer lacks the associated transmembrane and cytoplasmic domains normally present as part of the molecule.You experimentally link the $\alpha$ and $\beta$ subunits at the bases of their legs so that the ligand-binding regions of the $\alpha$ and $\beta$ subunits approach one another.Which of the following statements is true about the molecules formed?

Calcium ions form bridges between ________.

Mutations in other collagen genes can lead to a variety of distinct but related defects in collagen matrix structure,one of which causes hyperflexible joints and highly extensible skin.These defects are usually referred to as ______.

What can be described as solitary,nonadhesive,nonpolarized migratory cells?

What type of protein also seen in animal cells spans the plant plasma membrane and is thought to transmit signals from the cell wall to the cytoplasm?

The thicker walls seen in mature plants that no longer allow extensive growth of the cell wall are known as _______.

The enzyme embedded in the plant cell membrane that catalyzes the growth of a cellulose molecule is called _________.

Filaments connected to the dense plaque underlying the membrane in a hemidesmosome course outward into the cytoplasm.These filaments are composed of the protein _____ and are best known as ______.

Which of the following tissues are typically derived from mesenchymal cells?