Question

22.       The major components of a basal lamina are:

A.         type I collagen, laminin, and fibronectin

B.         type IV collagen, laminin, nidogen, and heparan sulfate

C.        type IX collagen, laminin, and nidogen

D.        type IV collagen, laminin, nidogen, and perlecan

Answer _________

23.       The plus ends of actin and microtubule filaments are more dynamic than the minus ends because:

A.         it is the end that is anchored to the microtubule-organizing center

B.         it is the end where the rates of both growth and shrinkage are fastest

C.        it is the end used preferentially by intracellular vesicles

Answer _________

Answer 1

22). The major components of basal lamina are:

Type  4th collagen, laminin, nidogen and perlecan.

So, option D) is correct.

A). Is incorrect because collagen Type 1 is the main component of  bone matrix (36% of bone is made up of collagen Type 1 and 3) and is not the main constituent of Basal Lamina.

B). Is incorrect because Heparan Sulfate occur in epithelial cells, fibroblasts etc. but in basal lamina it occurs as perlecan.

C). Is incorrect because type 9 collagen mostly occurs in hayaline cartilage and not in basal lamina.

23). The correct Option is :

B).  it is the end where the rates of both growth and shrinkage are fastest.

A). is incorrect because plus end is not the end that is anchored to the Microtubule-Organizing Center, where as it is the negative end which is anchored to the Microtubule-Organizing Centre.  

C). Is incorrect because  it is not the end used preferentially by intracellular vesicles but by the proteins called Plus-end tracking proteins.