Docs Viewer Cancer is not a disease of a single point mutation, rather independe

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Docs Viewer Cancer is not a disease of a single point mutation, rather independent mutation of at least 2-6 different genes is currently thought to be required for tumorigenesis and tumor cells often show mutations in greater than 10 different genes. The mutation rate in normal cells is about 1 per billion base pairs but in cancer cells the mutation rate is 100-1,000 times higher! This state of increased mutation frequency is called "genomic instability Using your knowledge of the gene disruptions involved in cancer suggest a possible mechanism for genomic instability. Explain your answer. Learn Marketing Skills Quick Marketing Lessons INSTALL

Explanation / Answer

in a genome the high rate or frequency of mutation is called genomic instability. As a result of higher frequency of mutation, several changes like rearrangement of chromosome, aneuploidy or changes in nucleotide sequence can arise. Genomic instability is the main reason behind cancer formation. There can be various caueses of genome instability such as instability of neucleotide or chromosome instability.

Nucleotide instability- this type of instability caused when there is an error in repair mechanism pathway of base excision or nucleotide excision. This can lead to generation of changes in few nucleotides as a result of nucleotide insertion, deletion or substitution. Small changes of this type or even single nucleotide alteration can lead to changes in phenotype. For e g a defect in nucleotide exicision repair mechanism results in xeroderma pigmentation. In xeroderma pigmentation, a XPA-XPG gene which is seven nucleotide long is responsible to generate a inheried syndrome. Individuals with xeroderma pigmentation will have a higher chance to develop skin cancer.

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