Questions 4-5: In eukaryotes, miR-5 is a microRNA with sequence complementarity
ID: 210493 • Letter: Q
Question
Questions 4-5: In eukaryotes, miR-5 is a microRNA with sequence complementarity to the 3’UTR of the mRNA transcript encoded by the BISgene. The BIS gene encodes for a protein that acts as an allosteric inhibitorof the protein p101. The p101 protein is a DNA methyltransferase (DNMT) that functions to methylate DNA.
4. In a breast cancer cell line, the p101 protein is active leading to misregulation of gene expression. In these breast cancer cells which of the following would be a correct prediction in regards to miR-5? (choose all that apply)
A. The gene encoding miR-5 is in a region of chromatin with hypoacetylation
B. The gene encoding miR-5 is in a region of chromatin with hyperacetylation
C. The gene encoding miR-5 in a region of euchromatin
D. The gene encoding miR-5 in a region of heterochromatin
E.The miR-5 transcript is translated at high levels
F. The miR-5 transcript is activating translation of the BIS gene
5. A different breast cancer cell line is found to have significantly decreased amounts of DNA methylation. Which of the following could explain why there is decreased DNA methylation in this cell line? (choose all that apply)
A. increased amounts of the p101 protein due to low levels of miR-5
B. decreased amounts of the BIS protein due to low levels of miR-5
C. increased amounts of the BIS protein due to low levels of miR-5
D. the absence of the BIS protein due to miR-5 inhibiting translation of the BIS mRNA transcript
E. the absence of the p101 protein due to miR-5 inhibiting transcription of the p101 mRNA transcript
A. The gene encoding miR-5 is in a region of chromatin with hypoacetylation
Explanation / Answer
Q.4 Answer- correct statement applies are B,C,E.
As stated in Question- p101 is active- it means its allostearic inhibitor is not present. Allostearic inhibitor is encoded by BIS gene. miR-5 binds to BIS gene and inhibiting its translation. As BIS gene product( allostearic inhibitor ) is absent p101 is active.
Gene which is actively translated is always found in Euchromatin in Acetylated form. Hence The gene encoding miR-5 is in a region of chromatin with hyperacetylation.The gene encoding miR-5 in a region of euchromatin (hyperacetylated).The miR-5 transcript is translated at high levels.miR-5 when present at high levels it binds to 3'UTR of BIS gene and inhibiting its translation. So its product allostearic inhibitor protein is absent. hence p101 is more active because its inhibitor is absent.
Q.5 Statement applies is C only. When miR-5 present in low level BIS protein will be translated more and hence allostearic inhibitor of p101 will be present that will inhibit p101 translation and hence less DNA will be methylated.
Among other option in E option is wrong because miR-5 inhibits traslation and not trascription so its wrong.
A is wrong because when p101 protein is increased DNA methylation will increase.
B is wrong because BIS when present in less amount (miR-5 will be at high level) p101 will be more active and DNA methylation will be more.
D is wrong because when BIS protein absent p101 will be more active and DNA methylation will be more.
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