Question 1

What type of cell adhesion molecule is associated with cells being held together by adherens junctions at the site of the junction?
A)adherins
B)selectins
C)IgSFs
D)integrins
E)cadherins

Accepted Answer

Cadherins are the type of cell adhesion molecule associated with cells being held together by adherens junctions at the site of the junction.

Question 2

Lymphocytes are isolated and labeled with radioactive isotopes.They are then exposed to frozen tissue sections of a lymphoid organ.What happens?
A)The lymphocytes bind uniformly to the sections.
B)The lymphocytes bind to each other.
C)The lymphocytes selectively adhere to the endothelial lining of venules in peripheral lymph nodes.
D)The lymphocytes selectively adhere to the endothelial lining of arterioles in peripheral lymph nodes.
E)The lymphocytes do not stick to the sections.

Accepted Answer

The selective adherence of lymphocytes to endothelial lining of venules in peripheral lymph nodes is known as homing. This process is essential for lymphocytes to migrate from blood to lymphoid organs. The adherence is selective in nature, as lymphocytes recognize and bind to specific adhesion molecules expressed on endothelial cells of venules in lymphoid organs. Therefore, the lymphocytes in this experiment would selectively adhere to the endothelial lining of venules in the frozen tissue sections.

Question 3

You genetically engineer nonadhesive cells to express one variety of cadherins and then mix the cells in various combinations.You then monitor their interactions.What do you observe?
A)The genetically engineered cells adhered preferentially to cells expressing one of the other cadherins.
B)The genetically engineered cells adhered preferentially to cells expressing the same cadherins.
C)The genetically engineered cells did not stick to any other cells.
D)The genetically engineered cells died.
E)The genetically engineered cells migrated to a different location.

Accepted Answer

Cells expressing the same variety of cadherins will preferentially adhere to each other due to the specificity of their binding. This is the basis of cell sorting and tissue formation during development. However, it is possible that the genetically engineered cells may also exhibit some degree of adhesion to cells expressing other cadherins, particularly if the differences between the cadherins are minor. Therefore, choice A is not entirely incorrect, but choice B is more accurate. Choices C, D, and E are not likely outcomes of this experiment.

Question 4

What can be described as solitary,nonadhesive,nonpolarized migratory cells?
A)a mesenchyme
B)cartilage
C)an epithelium
D)a mesothelium
E)an endothelium

Accepted Answer

Mesenchyme cells fit this description as they are solitary, nonadhesive, nonpolarized, and able to migrate. They are also found in connective tissue and give rise to various cell types such as fibroblasts, adipocytes, and chondrocytes.

Question 5

What is thought to be the origin of immunoglobulins?
A)They may be derived from immune system molecules in invertebrates.
B)They may be derived from cell-adhesion receptors in invertebrates.
C)They may be derived from cell-adhesion receptors in fish.
D)They may be derived from cell-adhesion molecules in amphibians.
E)They may be derived from immune system molecules in reptiles.

Accepted Answer

Immunoglobulins are believed to have originated from cell-adhesion receptors in invertebrates, which evolved to perform immune functions.

Question 6

Which of the following tissues are typically derived from mesenchymal cells?
A)mesodermal tissues
B)ectodermal tissues
C)only blood
D)only muscle
E)mesodermal tissues,blood and muscle

Accepted Answer

Mesenchymal cells are multipotent stromal cells that can differentiate into a variety of cell types, including those that form mesodermal tissues, blood, and muscle.

Question 7

The cells of the epiblast of a developing mammalian embryo display what cell adhesion molecules on their surfaces,molecules that presumably promote their close association with one another?
A)selectins
B)E-cadherins
C)P-cadherins
D)integrins
E)IgSFs

Accepted Answer

The cells of the epiblast of a developing mammalian embryo display E-cadherins on their surfaces, which promote their close association with one another. E-cadherins are a type of cell adhesion molecule that mediates calcium-dependent cell-cell adhesion. They are important in the formation of tight junctions between cells and the establishment of epithelial cell polarity.

Question 8

From the apical surface to the basal surface of an epithelial cell,what is the order of cell junctions observed in the junctional complex?
A)tight junction,belt desmosome,spot desmosomes,gap junctions
B)tight junction,gap junction,belt desmosome,spot desmosomes
C)belt desmosome,tight junction,gap junctions,spot desmosomes
D)belt desmosome,gap junctions,tight junctions,spot desmosomes
E)gap junctions,spot desmosomes,belt desmosome,tight junction

Accepted Answer

Tight junctions are the most apical, followed by belt desmosomes, spot desmosomes, and gap junctions.

Question 9

Calcium ions form bridges between ________.
A)successive domains of a given cadherin molecule
B)cadherins on adjacent cells
C)cadherins on the same cell
D)cadherins and IgSFs
E)IgSFs and selectins

Accepted Answer

The answer of Calcium ions form bridges between ________.
A)successive domains...

Question 10

The binding of lymphocytes to the endothelial lining of venules in peripheral lymph node frozen tissue sections could be blocked in what way? This demonstrated the existence of what kind of molecule?
A)Treatment with antibodies against specific lymphocyte surface glycoproteins,selectins
B)Treatment with antibodies against specific lymphocyte surface glycoproteins,IgSFs
C)Treatment with antibodies against specific lymphocyte surface glycoproteins,integrins
D)Treatment with antibodies against specific ECM glycoproteins,selectins
E)Treatment with antibodies against specific ECM glycoproteins,cadherins

Accepted Answer

The binding of lymphocytes to the endothelial lining can be blocked by treating with antibodies against specific lymphocyte surface glycoproteins, demonstrating the existence of selectins, which are involved in the adhesion process.

Question 11

L1 is an IgSF molecule that has been shown to be important in neural development; it is thought that it may be involved in axon growth within the embryonic nervous system.What evidence supports this statement?
A)L1 mutants always die.
B)L1 mutants show deficits in their vision.
C)People who die of L1-deficiency are often missing two large nerve tracts.
D)People who die of L1-deficiency are often missing a significant portion of their brain.
E)People who die of L1-deficiency are often missing a significant portion of their spinal cord.

Accepted Answer

The fact that people who die of L1-deficiency are often missing two large nerve tracts supports the idea that L1 is involved in axon growth within the embryonic nervous system.

Question 12

While most IgSF members are involved in various aspects of immune function,some of them mediate ________ cell-cell adhesion.
A)calcium-dependent
B)calcium-independent
C)magnesium-dependent
D)manganese-dependent
E)iron-independent

Accepted Answer

IgSF members that mediate cell-cell adhesion typically do so in a calcium-independent manner, meaning they do not require calcium ions to facilitate the interaction between cells.

Question 13

What can be described as a tightly adherent,polarized cell layer?
A)a mesenchyme
B)cartilage
C)an epithelium
D)a mesothelium
E)mesoderm

Accepted Answer

Only an epithelium is a tightly adherent, polarized cell layer that forms the lining of both internal and external surfaces of the body. Mesenchyme refers to loosely organized embryonic connective tissue, cartilage is a type of connective tissue, a mesothelium is a type of epithelium that lines body cavities, and mesoderm refers to the middle germ layer of embryonic development.

Question 14

The bonds that selectins form with their ligands become _______ when the interaction is __________.
A)stronger,placed under mechanical stress
B)weaker,placed under mechanical stress
C)stronger,exposed to a higher temperature
D)more elastic,exposed to a higher temperature
E)more elastic,placed under mechanical stress

Accepted Answer

Selectins form bonds with their ligands that become stronger when placed under mechanical stress, a phenomenon known as catch bonds, which enhances cell adhesion under flow conditions.

Question 15

What is the function of most IgSFs?
A)cell adhesion
B)cell division
C)mediating specific interactions of epithelial cells with cells needed for immune response
D)mediating specific interactions of lymphocytes with cells needed for the immune response
E)cell fusion

Accepted Answer

Most IgSFs function in mediating specific interactions of lymphocytes with cells needed for the immune response. While some IgSFs do play a role in cell adhesion and cell fusion, the majority are involved in immune system function.

Question 16

Cadherins appear to be important in holding cells together in __________ tissues.
A)mesenchymal
B)loosely cohesive
C)tightly cohesive
D)noncohesive
E)gel-like

Accepted Answer

Cadherins are transmembrane proteins that mediate calcium-dependent cell-cell adhesion in epithelial and endothelial tissues. They are particularly important in tightly cohesive tissues, where strong cell-cell adhesion is necessary for the proper function and integrity of the tissue.

Question 17

What determines the strength of adhesion between apposing cells held together by cadherins?
A)the length of the cadherins connecting the cells
B)the width of the cadherins connecting the cells
C)the amount of tryptophan in the cadherins connecting the cells
D)the number of cadherins in a cluster connecting the cells
E)the number of tyrosine residues in the cadherins connecting the cells

Accepted Answer

The strength of adhesion between apposing cells held together by cadherins is determined by the number of cadherins in a cluster connecting the cells. The more cadherins present, the stronger the adhesion will be. The other options (A, B, C, and E) are not relevant factors in determining the strength of cadherin-mediated adhesion.

Question 18

When tight junctions,gap junctions and desmosomes are arranged in a specific array,the assortment of surface specializations is called a(n)__________.
A)junctional array
B)synaptonemal complex
C)belt complex
D)junctional complex
E)spot complex

Accepted Answer

The specific arrangement of tight junctions, gap junctions, and desmosomes is called a junctional complex. This specialized structure is important for maintaining the integrity and function of the tissues they are found in.

Question 19

The loss of cadherin function may be instrumental in what disease state?
A)colds
B)the spread of benign tumors
C)the spread of malignant tumors
D)influenza
E)AIDS

Accepted Answer

Cadherins are cell adhesion molecules that play a role in maintaining tissue structure and preventing the spread of cells. Loss of cadherin function can lead to the breakdown of tissue barriers and promote the spread of cells, including malignant tumors. The other options do not involve cadherin function.

Question 20

Which of the following tissues are typically not derived from mesenchymal cells?
A)mesodermal tissues
B)ectodermal tissues
C)blood
D)muscle
E)bone

Accepted Answer

Ectodermal tissues, such as skin and nervous system, are derived from the ectoderm layer during embryonic development and not from mesenchymal cells. Mesodermal tissues (A), including muscle, bone, and blood (C, D, E), are derived from mesenchymal cells.

Quiz 7: Interactions Between Cells and Their Environment

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

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

You genetically engineer nonadhesive cells to express one variety of cadherins and then mix the cells in various combinations.You then monitor their interactions.What do you observe?

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

What is thought to be the origin of immunoglobulins?

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

The cells of the epiblast of a developing mammalian embryo display what cell adhesion molecules on their surfaces,molecules that presumably promote their close association with one another?

From the apical surface to the basal surface of an epithelial cell,what is the order of cell junctions observed in the junctional complex?

Calcium ions form bridges between ________.

The binding of lymphocytes to the endothelial lining of venules in peripheral lymph node frozen tissue sections could be blocked in what way? This demonstrated the existence of what kind of molecule?

L1 is an IgSF molecule that has been shown to be important in neural development; it is thought that it may be involved in axon growth within the embryonic nervous system.What evidence supports this statement?

While most IgSF members are involved in various aspects of immune function,some of them mediate ________ cell-cell adhesion.

What can be described as a tightly adherent,polarized cell layer?

The bonds that selectins form with their ligands become _ when the interaction is ____.

What is the function of most IgSFs?

Cadherins appear to be important in holding cells together in __________ tissues.

What determines the strength of adhesion between apposing cells held together by cadherins?

When tight junctions,gap junctions and desmosomes are arranged in a specific array,the assortment of surface specializations is called a(n) __________.

The loss of cadherin function may be instrumental in what disease state?

Which of the following tissues are typically not derived from mesenchymal cells?