With respect to microRNAs, which, if any, of the following statements, is false?

a) A microRNA normally works by binding to perfectly complementary sequences within an RNA transcript, usually an mRNA.

b) Like the great majority of mRNAs an miRNA is usually produced as a larger precursor RNA that is capped and has a 3’ poly(A) tail.

c) The precursor miRNA undergoes different types of post-transcriptional cleavage by endoribonucleases that are specific for double-stranded target sequences.

d) A nuclear endoribonuclease called dicer cleaves the miRNA precursor so that it forms a stem-loop RNA.

TLS Online TPP Program

#Question id: 15362

#Unit 4. Cell Communication and Cell Signaling

Aflatoxin a fungal metabolite found in moldy grains, induces

TLS Online TPP Program

#Question id: 15361

#Unit 4. Cell Communication and Cell Signaling

The chemical benzo(a)pyrene, found in cigarette smoke as well as in coal tar, undergoes metabolic activation in the lungs to form a potent mutagen that mainly, causes conversion of guanine (G) to thymine (T) bases, a transversion mutation, When applied to cultured bronchial epithelial cells, activated benzo(a)pyrene induces many mutations, including inactivating mutations of the p53 gene, at codon number______

TLS Online TPP Program

#Question id: 15307

#Unit 4. Cell Communication and Cell Signaling

In attached table some Tumor‐Suppressor Genes are given with their inherited syndrome; select correctly matched genes with their causing syndrome

TLS Online TPP Program

#Question id: 15306

#Unit 4. Cell Communication and Cell Signaling

The transformation of a normal cell to a cancer cell is accompanied  by the loss of function of one or more tumor‐suppressor genes. High‐throughput sequencing studies have identified hundreds of genes that are implicated as tumor suppressors in humans. Some of the better characterized genes;

Gene	Primary tumor	Proposed function
i) APC	Colorectal	Binds β ‐catenin acting as transcription factor
ii) BRCA1	Breast	DNA repair
iii) MSH2, MLH1	Melanoma, pancreatic	p16: Cdk inhibitor ARF: stabilizes p53
iv) E‐Cadherin	Breast, colon	Cell adhesion molecule
v) INK4a	Colorectal	Mismatch repair
vi) NF1	Neurofibromas	Activates GTPase of Ras

Choose incorrect matching regarding tumor‐suppressor genes/primary tumor/proposed functions;

TLS Online TPP Program

#Question id: 15305

#Unit 4. Cell Communication and Cell Signaling

The multi-hit model, which proposes that multiple mutations are needed to cause cancer, which of the following is incorrect regarding to this model?

TLS Online TPP Program

#Question id: 15304

#Unit 4. Cell Communication and Cell Signaling

An activating mutation of one of the two alleles of a proto-oncogene converts it into an oncogene, This can occur by EXCEPT