Question

The end of the chapter talks about DNA repair, and the discussion for this topic will follow up on this idea further. You should do further research on some aspect of DNA repair. For example: how it works the different types why it's important how it can go wrong what results when it goes wrong its importance to cancer.. Do not use other solutions. I need originality responses as well as IN TEXT CITATIONS AND A WORKS CITED REFERENCE. Please use 2 outside references.Thank you

Answer 1

Introduction: DNA damage may cause due to several physical and chemical agents causing DNA strand breaks, deletions, additions, repeatitions, nucleotide insertions in middle of the coding strand/normal DNA making it a mutagen or senseless strand which cannot give required product. Some of the agents are x-ray, gamma rays, ionizing radiation expotures in general. chemical mutagens include sodium azide, bromine, psoralen, benzene etc.

How to repair Damage DNA: The process of rectifying damaged DNA is done in many types.
1.Direct Repair
2.Base Excision Repair
3.Nucleotide Excision Repair
4.Mismatch Repair
5.Strand Break Repair

For example, we take a mammalian cell which is having a defective gene/damaged DNA. to rectify it generally BRCA1 on chromosome 17 and BRCA2 on chromosome 13, which are tumour suppressing genes, if one/both gets damaged/mutated then it would lead to cancerous growth of cell(breast cancer is caused y this mutation). generally a cell goes through cell cycle which have checkpoints to give the product, if mutations occur in these checkpoints(G1/S & G2/M) sequences the no regulation for cell division or nucleur material division in mitosis. hence causes the cancer.these are called as oncogenes. in such cases inhibitors are used to reduce the the activity of the gene. for BRAC1/2 preclincal trails have evidence for inhibitors likeheat shock protiens HSP90,proteasome,phosphatidylinositol 3-kinase(PI3K), CDK-1,Histone deacytlase(HDAC's) which show inhibitor affect on cell which cause transcriptional repression for BRAC1/2.

Defects which cause cancer cell survival or death Homologous Recombination Repair of Cancer.

Homologous Recombination(HR) repair,HR defects aggrevates genomic instability and cancer formation causing the cell death.if defect in HR repair then it causes intability in the cell and leads to cell death.