Cell Biology Lecture 7 & 8 Quiz

In epithelial tissues, what primarily provides the strength to the epithelial layer?

Channel-forming junctions create an impermeable barrier between cells.

What is the main role of anchoring junctions?

Epithelial cells are ______, meaning they have an apical and a basal side.

Match each type of cell junction with its primary function:

Which type of junction contributes to making a cell sheet selectively permeable?

The ECM in epithelial tissue is abundant with fibrous proteins, providing significant structural support.

Desmosomes anchor to what type of cytoskeletal filament?

Which type of junction primarily prevents leakage across an epithelial layer and is typically found on the apical side of the cell?

Gap junctions are typically located on the apical side of the cell.

What type of junction facilitates cell-to-cell communication through membrane-bound ligand-receptor interactions, such as the Notch/Delta pathway?

Anchoring junctions connect the cytoskeleton to structures outside the cell via transmembrane ______ proteins.

Which of the following cytoskeletal filaments are anchored between cells at adherens junctions?

Desmosomes and hemidesmosomes are associated with which type of cytoskeletal filament?

Match the anchoring junction with its appropriate description:

Cadherins mediate a general attachment of a cell to the extracellular matrix (ECM).

What is the primary role of adherens junctions in epithelial tissues?

Cadherins directly attach to the cell nucleus, influencing gene transcription.

What cytoskeletal element is directly linked to cadherins within adherens junctions?

The cluster of cadherins linked to actin filaments that create a structural bridge across epithelial cells is called an ______.

What process relies on the coordinated action of adherens junctions to shape epithelial sheets?

Adherens junctions only provide structural support and do not transmit signals into the cell interior.

What results from pressure inducing invagination in epithelial cells linked by adherens junctions?

Match the following components with their role in adherens junctions:

What happens to cadherin molecules when calcium concentration drops below 1mM?

Cadherins utilize a 'Velcro principle' by forming one very strong, high-affinity interaction with neighboring cells.

According to the 'Velcro principle,' what is the main advantage of cadherins having multiple, lower-affinity interactions rather than one strong interaction?

Unlike receptors for soluble signal molecules, cadherins typically bind to their partners with relatively ______ affinity.

What is the primary mechanism by which cadherins create strong attachments between cells?

Cadherins function as a 'glue,' making cell surfaces generally sticky and promoting adhesion to any cell type.

What type of attachment do cadherins form?

Match the example with the description:

What is a potential consequence of overproduction of cadherins like E-cadherin?

Why might a protein localized at an adherens junction, such as b-catenin, need a nuclear localization signal (NLS)? Provide a succinct scientific justification.

Beta-catenin's sole function is to facilitate cell-cell adhesion at adherens junctions.

In addition to its role at adherens junctions, beta-catenin is involved in WNT signalling and, within the nucleus, activates the transcription of ______ genes.

Sam discovers a mutation in the b-catenin gene during PCR cloning that changes a conserved arginine to a methionine within a predicted nuclear localization signal (NLS). Which of the following implications is MOST relevant regarding b-catenin's function?

What cellular component do desmosome junctions link to in heart muscle cells, providing mechanical strength?

The formation and breakdown of cellular attachments have no effect on a cells' internal processes.

What is the primary function of adherens junctions?

Desmosomes utilize the ______ principle to link to another cell.

Which of the following is a key difference between adherens junctions and desmosomes?

What type of protein promotes cell-cell interactions by binding to the same subtype on adjacent cells?

Desmosomes are polar structures that create a belt across cells.

What effect would WNT activation have on cadherin genes?