1.Explain briefly why changes in oncogenes result in more rapid progressrion of
ID: 6756 • Letter: 1
Question
1.Explain briefly why changes in oncogenes result in more rapid progressrion of a cancer compared to changes in tumorsuppressor genes2.many point mutations do not have any effect on the gene product.what Aretwo possible explanations for this observation?
3.what would be the consequences of a two nucleotide-deletion mutation in the middle of the first exon of a protein-coding gene?
4.fillin the blank
a eukaryotic DNA sequence that affects transcription at distant promoters is called an.......
RNA polymerase must bind toa region of DNA called a(an)......in order to begin transcription.
Explanation / Answer
1. when a tumor supressor gene is mutated, there is still another unmutated and functioning copy on the homologous chromosome (recall: we have 2 copies of each gene). when a preoncogene gets mutated, it turns into an oncogene, by definition the function of an oncogene is to drive the cell cycle forward. so they will be busying themselves in rapidly duplicating the cells and disregarding mutations, actively causing tumors 2.Most amino acids are encoded by several different codons. For example, if the third base in the TCT codon for serine is changed to any one of the other three bases, serine will still be encoded. Such mutations are said to be silent because they cause no change in their product and cannot be detected without sequencing the gene (or its mRNA). another, explaination is the proofreading that occurs later... error fixed, no harm, no foul. another explaination is that the point mutation occurred in noncoding regions, obviously, it can't hurt. 3. a two-nucleotide deletion will definitely cause frameshifting and the end result is a whole different product. 4.eukaryotic DNA sequence that affects transcription at distant promoters is called an ENHANCER (plz look this up, i think this is what you're looking for) RNA polymerase must bind to a region of DNA called a PROMOTER in order to begin transcription. (otherwise sigma factor won't bind) k..hope that helps
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