Cell signalling unit-4 December 2017 pyq | csir net Dec 2017 unit 4 pyq part B & c with explanation

In this video we will discuss about the following questions:-

Unit 4 | Part - B

048. In a signalling event, binding of an extracellular ligand activates G-protein coupled receptor (GPCR) that eventually activates phospholipase C-ẞ. Which one of the following statements truly reflects the function of phospholipase C-?

a. Phospholipase C-ẞ converts PI(3, 4, 5)P, to PI(4, 5)P2

b. Phospholipase C-ẞ converts PI(4)P to PI(4, 5)P2

c. Phospholipase C-ẞ converts PI(4, 5)P, to diacylglycerol and IP3.

d. Phospholipase C-ẞ converts PI(5)P to PI(4, 5)P2.

049. Proteins with cytoplasmic domains having tyrosine kinase activity do not act as receptors for

a. Epidermal growth factor (EGF)

b. Platelet-derived growth factor (PDGF)

c. Insulin

d. Transferrin

050. Junctions which tether cytoskeletal filaments inside the cell are known as
St. Which one of the following human serum immunoglobulins takes part in classical complement fixation pathway?
December 2017

Unit 4 | Part-C

152. In a type of signal transduction pathway, ligand binding to a receptor triggers activation of a receptor-associated kinase. This kinase may be an intrinsic part of the receptor protein or tightly bound to the receptor. Receptors in which the tyrosine kinase is an intrinsic part of its polypeptide chain are called the receptor tyrosine kinase (RTK). Which one of the following statements regarding RTK is incorrect?

a. All RTKs have three essential components: an extracellular domain containing ligand binding site, a transmembrane

domain and a cytoplasmic segment that includes a domain with protein tyrosine kinase activity.

b. Most RTKs are monomeric and ligand binding to the extracellular domain induces formation of receptor dimers.

c. All cytokine receptors belong to RTKs and cytokine binding activates tyrosine kinase and receptor dimerization.

d. Ligand binding to RTK leads to autophosphorylation of the protein tyrosine kinase in the cytoplasmic domain. The activated kinase then phosphorylates several tyrosine residues in the receptor's cytoplasmic domain.
53. Two classes of genes-proto-oncogene and tumor suppressor gene usually contribute to the development of

cancer. Following are some of the statements regarding both the genes.

P. Proto-oncogenes result in the development of cancer by gain-of-function mutation whereas tumor suppressor gene leads to cancer development by loss-of-function mutation.

Q. Proto-oncogenes result in development of cancer by loss-of-function mutation whereas tumor suppressor gene

leads to cancer development by gain-of-function mutation.

R. Mutation in both the alleles of a proto-oncogene is required for induction of cancer whereas mutation in one of the two alleles in tumor suppressor gene is sufficient for promoting tumorigenesis.

S. Mutation in one of the two alleles in proto-oncogene is sufficient for induction of cancer whereas mutation in both the alleles of a tumor suppressor gene is required for promoting tumorigenesis.
154. Two important features which aid the development of a tumor and its metastasis are epithelial-to-mesenchymal transition and angiogenesis. A student tested four cell lines to determine their invasiveness and proliferation capability by checking the expression of VEGF-A, TWIST and Cyclin D1. Which one of the following figures is most likely to exhibit the characteristics of a highly metastatic cancer cells?
055. Several types of molecules including the transmembrane glycoproteins can function as matrix receptors and o receptors. However, the principal receptors on animal cells for binding most extracellular matrix proteins are the integrins. Which of the following statements is not true for integrins?

a. Integrins are transmembrane linker proteins that link to the cytoskeleton.

b. An integrin molecule is composed of two non-covalently associated glycoprotein subunits & and B. Both subunits span the cell membrane, with short intracellular C-terminal tails and large N-terminal extracellular domains

c. The extracellular portion of the integrain dimer binds to specific carbohydrate residues in extracellular matrix proteins or to ligands on the surface of other cells.

d. The intracellular portion binds to a complex of proteins that form a linkage to the cytoskeleton.

056. Major histocompatibility complex (MHC) molecules are encoded by a cluster of genes called MHC locus. There are severs

reasons why an MHC molecule on the surface of a cell is important. Which one of the following reasons is income?

a. To display self class I to demonstrate that the cell is normal and healthy.

b. To display foreign-peptide in class I to show that the cell is infected and to engage with T helper cells. c. To display a self-peptide in class I and II to test developing T cells for autoreactivity.

d. To display a self-peptide in class I and II to maintain tolerance to self-proteins.

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