Imagine a chromosome translocation event that brings a gene encoding a histone acetyl transferase enzyme from its original chrom
osomal location to a new one near heterochromatin. Which of the following scenarios is definitely NOT going to happen? A. The gene gets silenced due to heterochromatin expansion, leading to the misregulation of gene expression for a number of critical genes.
B. The translocation event also brings along a chromatin barrier that can prevent heterochromatin expansion into the gene, and there is no phenotypic anomaly.
C. Since the gene encodes a histone acetyl transferase, it resists heterochromatin expansion by acetylating its own histones.
D. 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 histones,this is the scenario which is not going to happen
In eukaryotic transcription initiation of a gene require change in chromatin structure(chromatin remodeling) because promoter and other regulatory elements of DNA exposed after removal of histone core
Chromatin remodeling can be induced by two separate mechanisms: Histone modification and histone displacement
By histone modification-it is an enzyme dependent but energy independent;includes acetylation,methylation and phosphorylation
Histone acetylation occurs on Lysine residue of H3 and H4 which is present in histone tail
Histone acetylation catalysed by an enzyme called as histone acetyl transferase(HAT)
Histone acetylation neutralises the positive charge of histone core and facilitate their dissociation
Histone acetylation favours gene expression
Histone deacetylation is the removal of acetyl group from histone tail which is catalysed by histone deacetylated enzyme and is always associated with gene repression
