Question

6.         Dynamic instability is:

A.         the phenomenon where microtubules alternate between a period of slow growth and a period of rapid disassembly.

B.         the same as treadmilling

C.        the process whereby myosin II motor proteins "walk" along actin filaments

Answer _________

7.         Each of the following is a fundamental characteristic of basal laminae except:

A.         it is an essential structural component of epithelium

B.         it is composed of diverse ECM proteins including laminins

C.        it is only associated with epithelial cells

D.        it utilizes type IV collagen for tensile strength

Answer _________

8.         Talin is a protein that:

A.         links integrins to the actin cytoskeleton

B.         links the intracellular domain of cadherins to the actin cytoskeleton

C.        links integrins to the ECM

Answer _________

9.         Outside-in signaling refers to what phenomena?

A.         the ability of different ECM proteins to influence how integrins link to the actin cytoskeleton

B.         the ability of b-catenin/E-cadherin interactions to influence cell adhesion

C.        the ability of linkage of integrins to the actin cytoskeleton to directly influence how             integrins bind to components of the ECM

D.        none of the above

Answer _________

10.       Selectins are cell surface carbohydrate-binding proteins that:

A.         contain multiple immunoglobulin-like domains

B.         attach to the actin cytoskeleton via anchor proteins

C.        are often referred to as CAMs or cell adhesion molecules

D.        all of the above

Answer _________

11.       Cadherin-dependent cell sorting refers to:

A.         the ability of E-cadherin to engage in heterophilic binding to N-cadherin

B.         the observation that cells expressing low levels of E-cadherin will preferentially interact with        cells that also express a low level of E-cadherin

C.        the ability of cells to interact specifically with different ECM proteins

D.        none of the above

Answer _________

Answer 1

Ans-6. A. the phenomena where microtubules alternate between period of slow growth and period of rapid reassembly.

Dynamic instability is switching between growing that is polymerizing and shrinking that is depolymerizing states of microtubules.

Ans-7. D. It utilizes type IV collagen for tensile strength

In basal lamina, type VII collagen extend from basal lamina into the underlying reticular lamina. So it is type VII collagen which provides strength.

Ans-8. A. links integrin to the actin cytoskeleton

Talin is a cytoskeletal protein at the regions of cell substratum contact and in lymphocytes at cell to cell contacts. It links imtegrins to actin cytoskeleton either directly or indirectly.

Ans-9. C. the ability of linkage of integrins to the actin cytoskeleton to directly influence how integrins bind to components of ECM.

Outside in signalling transfers integrin mediated external signals to the inside of the cells. In outside in signalling through integrins, ligands bind to extracellular integrin domains.