Question

I need to write 250 words

topic: DNA repair genes
The writing must include definition, mutation, and pattern of inheritance, symptoms, and diagnosis. all important things

Answer 1

Ans ) The human genome, like other genomes, codes information to guard its peculiar integrity DNA repair enzymes uninterruptedly monitor chromosomes to correct damaged nucleotide residues produced by exposure to carcinogens and cytotoxic compounds. The damage is partly a consequence of environmental agents such as ultraviolet (UV) light from the sun, inhaled cigarette smoke, or incompletely defined dietary factors. However, a large proportion of DNA alterations are caused unavoidably by endogenous weak mutagens including water, reactive oxygen species, and metabolites that can act as alkylating agents. Very slow turnover of DNA consequently occurs even in cells that do not proliferate. Genome instability caused by the great variety of DNA-damaging agents would be an overwhelming problem for cells and organisms if it were not for DNA repair.

The role vital for the three different forms of excision repair are explained individually. These are base excision repair (BER), nucleotide excision repair (NER), and mismatch repair (MMR). Other segments confer direct reversal of DNA damage, recombination and rejoining pathways for repair of DNA strand breaks, and DNA polymerases that can bypass DNA damage

The mutation is any alteration in genes that interfere in the normal functioning of genes. Some of them are heritable and some of them are non- heritable too.

The connotation of MMR faults with augmented risk of cancer progress was first observed in colorectal cancer patients that approved inactivating germline mutations in MMR genes and the disease was named as hereditary non-polyposis colorectal cancer (HNPCC). Presently, a growing list of cancers is found to be MMR defective and HNPCC has been renamed Lynch syndrome (LS) partly to embrace the linked risk of evolving extra-colonic cancers. In addition, a number of non-hereditary, frequently epigenetic, alterations of MMR genes have been defined in sporadic tumors. As well deliberating a strong cancer predisposition, genetic or epigenetic inactivation of MMR genes also renders cells resistant to some chemotherapeutic agents. Therefore, diagnosis of MMR deficiency has important implications. Some of the alterations found in MMR genes have already been well defined and their pathogenicity assessed