Site MapHelpFeedbackCapítulo 7
Capítulo 7
(See related pages)

1. Selectin-mediated cell adhesion would be inhibited by trypsin, neuraminidase, and EGTA. L1-mediated cell adhesion would be inhibited by trypsin and, possibly by RGD peptides if the adhesion was based on L1-integrin interactions, the integrin had an RGD-binding site, and this site was close enough to the L1-binding site to interfere.

2. Anti-fibronectin antibodies would disrupt neural crest cell migration; anti-laminin antibodies would disrupt migration or primordial germ cells; and fibroblast adhesion might be disrupted by RGD peptides, which would block formation of focal contacts, or by various types of antibodies.

3. Migration of neural crest cells. Any process that required tight linkage of cells to their extracellular matrix might be disrupted, because fibronectin is an important linker between the cell surface and other materials of the ECM.

4. The molecule of 1500 might be rod-shaped, whereas the molecule of 1200 might be globular.

5. Both contain fibrous materials to resist pulling forces and an amorphous matrix to resist compression.

6. Both types of adhesive junctions are important in maintaining the integrity of an epithelium. Hemidesmosomes are important in holding the layer to the underlying substrate and desmosomes in holding the cells to one another.

7. Cadherins. They are widely distributed among tissues, and they act by binding to the same cadherin on the surface of other cells, thus mediating adhesion of similar types of cells. Aggregation and sorting out could be carried out in the presence of an anti-cadherin antibody, which should block cadherin-cadherin interactions.

8. The follicle cells and cardiac muscle cells form gap junctions with one another. As a result, the FSH would bind to receptors on the follicle cells, stimulating the production of cyclic AMP molecules that could diffuse through the gap junctions into the cardiac muscle cells, causing their contraction.

9. Nearly all animals possess some type of skeleton that maintains support, thereby eliminating the structural requirements for a cell wall. In addition, the cells of animals are bathed in a fluid that is maintained isotonic to the cells, thereby eliminating the need for a cell wall to resist the build up of osmotic pressure.

10. Because gap junctions assemble from connexons that diffuse within the plane of the plasma membrane into the region where the gap junction is forming. Once there, connexons from apposing membranes become aligned to form a continuous passageway. A decrease in temperature would be expected to reduce the ability of integral proteins to diffuse through the membrane.

11. In a tight junction, the encircling nature of the cell-contact forms a seal, like a gasket, that prevents passage of solutes between the cells. If the junction were not continuous, it would leave openings between the cells. Desomosomes and gap junctions can mediate adhesion and communication without having to form such a seal.

12. e.g., cause the loss of the desmotubule. Examine the cells under the electron microscope and compare to noninfected.

13. Erythrocytes remain as free circulating cells; they are characterized by a lack of interaction with either other cells or an extracellular matrix.







Biología celular y molecularOnline Learning Center

Home > respuestas preguntas 2 > Capítulo 7