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45. A region of the chromosome 1000 base pairs upstream of the promoter for the gene pbxH was deleted. This resulted in decreased expression of pbxH. This region is most likely a/an A. intron B. gene for a transcription factor C. gene for the RNA polymerase D. proximal control region E. enhancer 46. Methylation (actually, increased or hypermethylation) of the GSTP1 promoter is a common DNA alteration in certain cancers. Which of the following best characterizes this alteration? A. Increased expression of a tumor suppressor gene B. Increased expression of a protooncogene C. Decreased expression of tumor suppressor gene D. Decreased expression of a proto-oncogene 47. Epithelial-mesenchymal transitions may be important in which of the following A Development B. Cleavage C. Metastasis (the spread of cancer from one organ or part to another) D. A and C E. A, B, and C

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Ans. 45) the region is enhancer, it is present upstream, downstream or can also in intron at approximately 1000 bp away the start site. It help the binding of activators which is required for the speed up the expression of gene. If enhancers are deleted then gene will express but the expression rate will slow down as no activator will be able to bind the enhancer.

Ans. 46) DNA methylation is an alternative for cancer development, it cause the silencing of the gene without altering it's function or structure. Mainly it is overved in the promoter region of gene. Usually tumor suppressor genes are methylated, esults in silencing of tumor suppressor gene which leads to cancer, because if these genes are not functioning then cell will continuously divide and there will be no signal for stopping division. So methylation decreases the expression of tumor suppressor gene and cause cancer.

Ans. 47) epithelial mesenchymal transition is important in development and metastasis. EMT is process by which cells loses it's adhasive property and gain migratory property to become mesenchymal stem cells. During development the embryonic stage corresponding to the formation of the three primary germ layers: ectoderm, mesoderm and endoderm, gastrulation involves either collective cell migration through invagination or involution (partial EMT), or individual cell migration by ingression (EMT).

As most tumors are carcinomas, i.e. derived from epithelia. Carcinomas initially remain confined within a basement membrane, but eventually infiltrate into the surrounding stroma and intravasate into the blood and lymph vessels where they are passively transported to distant sites. This transport is known as metastasis and EMT play role in metastasis.