The cells from a person’s malignant tumor were subjected to insitu hybridization using a probe that recognizes a unique sequenceon chromosome 14. The probe was detected only once in each ofthe cells. Explain this result, and speculate on its significance withregard to the malignant characteristics of these cells.

You have treated undifferentiated embryonic stem cells (ESCs) with sonic hedgehog (Shh)for several days. This should induce a neural fate in your ESCs and you hope that you havebeen successful in differentiating the ESCs into NSCs. What is one assay you could use to testwhether your cells had differentiated into NSC-like cells? Name and shortly describe the assay?

A small fraction—2 to 3%—of all cancers, acrossmany subtypes, displays a quite remarkable phenome-non: tens to hundreds of rearrangements that primarilyinvolve a single chromosome, or chromosomal region.The breakpoints can be tightly clustered, with several in afew kilobases; the junctions of the rearrangements ofteninvolve segments of DNA that were not originally closetogether on the chromosome. The copy number of varioussegments within the rearranged chromosome was foundto be either zero, indicating deletion, or one, indicatingretention.You can imagine two ways in which such multi-ple, localized rearrangements might happen: a progressiverearrangements model with ongoing inversions, deletions,and duplications involving a localized area, or a cata-strophic model in which the chromosome is shattered intofragments that are stitched back together in random orderby nonhomologous end joining (Figure Q20–2).A. Which of the two models in Figure Q20–2 accountsmore readily for the features of…

The idea that sperm carry more mutations thanoocytes makes sense. Explain how?

Is it correct to say that the palladin gene causes cancer?

A student has identified Gene X as mutated in many liver tumors. The student transfects primary hepatocytes extracted from a biopsy of a normal liver and finds no evidence of cell proliferation of the cells. In contrast, when they transfect the liver cell line (HEPG2) they see evidence of proliferation. Explain the different results (limit 4-5 sentences).