Nuclei have been isolated from a stem cell line at 0, 1, 2, and 4 days after the
ID: 214912 • Letter: N
Question
Nuclei have been isolated from a stem cell line at 0, 1, 2, and 4 days after the cell line has been induced to differentiate into muscle type cells. The nuclei are subjected to digestion with DNase, the DNA is then extracted from the nuclei and cleaved with a restriction enzyme that cleaves the DNA external to genes X and Y. The digestion products are run on a gel and analyzed by Southern blots using a labeled probe that binds to either X or Y DNA (or RNA). The results of this experiment are shown on the Southern blot below at the left. The experiment is repeated, but without DNase, and the results are shown on the Southern blot below in the middle. Finally, RNA, extracted from the cells at days 0, 1, 2 and 4 after induction, is run on gels which are then blotted and probed for the presence of X or Y RNA, as shown in the Northern blot below, right.
c. Is either gene X or gene Y likely to encode a muscle cell specific protein?
d. Is either gene X or gene Y likely to encode a “housekeeping” protein? (Housekeeping proteins are required for the survival of all cells.)
e. If the histone acetylase activity in the stem cell line above were to be inhibited, how would the results obtained on any of the three blots above likely differ?
Days of induction01 2 4 0 1 24 Probe X Probe Y | Southern blot Southern blot Northern blotExplanation / Answer
C. Both involved in muscle cell specific protein.
D. No, either gene X or gene Y likely to encode a “housekeeping” protein. Because both are not expressing all the time.
E. If inhibited the histone acetylase activity which decrease the expression of genes through transcription. No differentiation occurs.
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