Question

12.       Which of the following statements regarding integrins is true?

A.         they function as a heterodimer of alpha and beta integrins

B.         they utilize adaptor proteins such as beta-catenin to link to the actin cytoskeleton

C.        they can bind to more than one type of ECM protein

D.        all of the above

Answer _________

13.       The glycoprotein fibronectin has which of the following features:

A.         it is calcium dependent

B.         it functions as a dimer connected by disulfide bonds

C.        it is a glycosaminoglycan

D.        all of the above

Answer _________

14.       The statement "assembly of an ECM meshwork (like a basal lamina) is a cell-mediated process" refers to:

A.         the observation that cell surface ECM binding proteins like integrins are required for ECM            assembly

B.         the observation that cells secrete ECM proteins

C.        the observation that proteoglycans can function as co-receptors for signaling molecules

D.        the observation that matrix metalloproteinases degrade ECM

Answer _________

15.       A single mutation event in an oncogene can promote cancer, this is because:

A.         single mutation events inactivate both chromosomal copies of a oncogene

B.         increased expression or activity of one chromosomal copy of a oncogene can be enough             to promote cell division

C.        oncogenes function in a recessive manner

D.        oncogenes encode proteins that promote apoptosis

Answer _________

16.       Metastasis is referred to as an inefficient process. This is because:

A.         invasiveness is a difficult step

B.         tumor cell colonization of a remote tissue site is a difficult step

C.        it is rare for a tumor cell to acquire the ability to successfully undergo all the steps of metastasis

D.        all of the above

Answer _________

17.       During cancer, tumor suppressor genes function in a recessive manner, this means that:

A.         an activating mutation occurred in one chromosomal copy of the tumor suppressor gene

B.         inactivating mutations occurred in both chromosomal copies of the tumor suppressor gene

C.        a dominant mutation occurred in the tumor suppressor gene

Answer _________

Answer 1

12, D Al the statements are true

13. B Fibronectin is calcium independent, proteoglycan in nature.

14. B all the components of ECM are secreted by cells

15. B there are two types of mutations- one dominant and the other recessive. For dominant mutation we need only one gene to be mutated, while in recessive there should be knock out on both the chromosomes (in a diploid)

16. B Fomation of blood vessels in a newly formed tumor is a challenge as many factors are required for this. We need to understand this that tumors are a toatl different type of tissue and they ave a different metabolic pathway.

17 B As explained in 15th answer, we need mutations on both chromosomes to have a recessive tumor.