Imagine a chromosome translocation event that brings a gene encoding a histone a
ID: 141810 • Letter: I
Question
Imagine a chromosome translocation event that brings a gene encoding a histone acetyl transferase enzyme from its original chromosomal location to a new one near heterochromatin. Which of the following scenarios is definitely NOT going to happen? The gene gets silenced due to heterochromatin expansion, leading to the misregulation of gene expression for a number of critical genes. The translocation event also brings along a chromatin barrier that can prevent heterochromatin expansion into the gene, and there is no phenotypic anomaly. The level of the gene product decreases due to a position effect leading to an imbalance in the chromatin state of the cell that results in the activation of programmed cell death Since the gene encodes a histone acetyl transferase, it resists heterochromatin expansion by acetylating its own histonesExplanation / Answer
Answer: Option C
Explanatin: When the HAC gene is placed near the heterochromatin region, it may get silenced due to the heterochromatin expansion. This leads to misregulation of gene expression.
Translocation event can also bring along a chromatin barrier. This barrier insulator prevents the heterochromatin expansion by disrupting heterochromatin formation pathway. Heterochromatin expansion can also be disrupted by HAC enzyme.
When the HAC gene is tranlocated, it may the affect the gene expression of HAC. This is known as position effect. This alter the gene expression of the entire cell thereby preventing growth and cell division. Since the histone acetylation mechanism is inhibited this prevents the expression of essential gene which are required to carry out the Programmed cell death pathway. In simple words, all the pathway which requires transcription will come to an halt. Pathway assocaiated with cell growth, division and Programmed cell death will come to an halt.