The BRCA2 provides instructions for making a protein that acts as a tumor suppre
ID: 84808 • Letter: T
Question
The BRCA2 provides instructions for making a protein that acts as a tumor suppressor. Tumor suppressor proteins help prevent cells from growing and dividing too rapidly or in an uncontrolled way. The BRCA2 protein is involved in repairing damaged DNA. In the nucleus of many types of normal cells, the BRCA2 protein interacts with several other proteins to mend breaks in DNA. These breaks can be caused by natural and medical radiation or other environmental exposures, and they also occur when chromosomes exchange genetic material in preparation for cell division. By helping to repair DNA, the BRCA2 protein plays a critical role in maintaining the stability of a cell's genetic information. Researchers have identified more than 1, 800 mutations in the BRCA2 gene. Many of these mutations are associated with an increased risk of breast cancer in both men and women, as well as several other types of cancer. The BRCA2 gene encodes for a 32 kD protein. You are interested in studying the BRCA2 gene and you intend to compare the sequence of the modern human BRCA2 gene with that of Homo foresiensis. You have received a recombinant plasmid containing a cDNA copy of the H floresiensis BRCA2 gene. You name this plasmid, pHOB1, pHOB1 was created by cloning the H. floresiensis cDNA into the plasmid vector pUC57 (see Figure below) using the BamHI restriction enzyme site in the multiple cloning sequence (MCS), The MCS is an artificial sequence that contains multiple restriction enzyme sites (shown in the expansion box to the right in the figure) but the MCS itself does not interrupt the expression of the lacZ gene. The lavZ gene encodes for an enzyme, beta-galactosidase. beta-galactosidase will convert a colorless substrate x-gal (5-bromo-4-chloro-3-indoly-beta-D-galactopyranoside) into an intensely blue product. if is active in the bacterial the carrying pHoB1 be blue when gal is beta-galactosidase is inactive then the E. coil then the bacteria carrying pHOB1 will be blue when X-gal is present. If beta-galactosidase is active in the bacterial host, E. coli, then the bacteria carrying pHOB1 will be blue white, their default color, when X-gal is present. Below is a map of the pUC57 plasmid vector. Ap^R is the ampicillin resistance genr. rep is the origin of replication. lacZ is the gene encoding beta-galactosidase. In the lacZ gene, the MCS is an engineered sequence containing multiple restriction enzyme sites. Insertion of foreign DNA in the MCS region will change the mRNA sequence and thus the primary structure of beta-galactosidase. The size of pUC57 is 2710 bp. The number indicate bp location relative to bp 1 at the top increasing in clockwise direction.Explanation / Answer
The BRCA2 gene contains 27 exons, 10,254 base pairs coding for a protein of 3418 amino acids. The BRAC2 gene approximately covers 70 kb of genomic DNA. So the possible size of pHOB1 is approximately 3582 bp.
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