Question

BRCA1 and BRCA2 Genes

• Discuss how the primary structure of nucleic acids is the order of bases in the polynucleotide sequence, and the secondary structure is the three-dimensional conformation of the backbone.
• Discuss the monomers of nucleic acids are nucleotides.
• Discuss how the bases are bonded to the sugars, forming nucleosides.
• Summarize how nucleosides are linked by ester bonds to phosphoric acid to form the phosphodiester backbone.
• Specific proteins called single-strand binding proteins bind to the single-stranded regions and protect them from nucleases.
• Spontaneous mutation of bases and insertion of the wrong nucleotide would normally lead to an error every 10⁴ to 10⁵

Are the BRCA1 and BRCA2 genes reliable predictors of cancer and if so, should the person take the steps necessary to reduce their risk, such as a double mastectomy? Why/why not?

• Be sure to cite any outside sources in current APA format.

Answer 1

Answer-  DNA and RNA are the types of nucleic acid found in our cells. Their primary structures constitute linear polymers composed of monomers called nucleotides. DNA and RNA consists of four different nucleotide.All nucleotides have a common structure: a phosphate group linked by a phosphoester bond to a pentose (a five-carbon sugar molecule) that in turn is linked to an organic base. All nucleotides have a common structure: a phosphate group linked by a phosphoester bond to a pentose (a five-carbon sugar molecule) that in turn is linked to an organic "base".

The nitrogen bases adenine and guanine are purine in structure and form a glycosidic bond between their 9 nitrogen and the 1' -OH group of the deoxyribose. Cytosine, thymine and uracil are pyrimidines, hence the glycosidic bonds forms between their 1 nitrogen and the 1' -OH of the deoxyribose. For both the purine and pyrimidine bases, the phosphate group forms a bond with the deoxyribose sugar through an ester bond between one of its negatively charged oxygen groups and the 5' -OH of the sugar.The polarity in DNA and RNA is derived from the oxygen and nitrogen atoms in the backbone. Nucleic acids are formed when nucleotides come together through phosphodiester linkages between the 5' and 3' carbon atoms.The linear sequence of nucleotides linked by phosphodiester bonds constitutes the primary structure of nucleic acids. It is the linear sequence of nucleotides that make up the primary structure of DNA or RNA. Sequences are presented from the 5' to 3'. Secondary structure is the set of interactions between bases, i.e., which parts of strands are bound to each other. In DNA double helix, the two strands of DNA are held together by hydrogen bonds. The nucleotides on one strand base pairs with the nucleotide on the other strand. The secondary structure is responsible for the shape -that the nucleic acid assumes. Polynucleotides can twist and fold into three-dimensional conformations stabilized by noncovalent bonds; in this respect, they are similar to polypeptides. Although the primary structures of DNA and RNA are generally similar, their conformations are quite different. Unlike RNA, which commonly exists as a single polynucleotide chain, or strand, DNA contains two intertwined polynucleotide strands. This structural difference is critical to the different functions of the two types of nucleic acids.

BRCA1 and BRCA2 are two examples of genes that raise cancer risk if they become altered as they are tumor suppressing genes. Having a mutant BRCA gene greatly increases a woman's chance of developing breast cancer and ovarian cancer. This was the reason Angelina Jolie had preventative breast cancer surgery, followed by ovarian cancer surgery. They also increase a man's chance of developing male breast cancer and prostate cancer. If a woman wishes to reduce her risk of developing breast cancer she could consider risk-reducing mastectomies. This is the surgical removal of breast tissue to try to prevent the development of cancer. There are various types of operations, but, in general, as much breast tissue as possible is removed. There will be some breast tissue remaining but the lifetime risk of breast cancer would generally be reduced by 90-95%. Women who have the risk-reducing surgery will no longer need annual mammographic screening because they will have very little breast tissue left. Reconstructive surgery can be offered at the same time as the risk-reducing mastectomies.