AP BIOLOGY

Detailed explanation-1: -A transcriptional activator is a protein (transcription factor) that increases transcription of a gene or set of genes. Activators are considered to have positive control over gene expression, as they function to promote gene transcription and, in some cases, are required for the transcription of genes to occur.

Detailed explanation-2: -The gene regulatory proteins allow the individual genes of an organism to be turned on or off specifically. Different selections of gene regulatory proteins are present in different cell types and thereby direct the patterns of gene expression that give each cell type its unique characteristics.

Detailed explanation-3: -A gene is switched “on” when the portion of chromatin where it is located “opens.” This process involves proteins that add little chemical modifications to histones or to the DNA.

Detailed explanation-4: -DNA Methylation Typically, this group is added to specific places on the DNA, where it blocks the proteins that attach to DNA to “read” the gene. This chemical group can be removed through a process called demethylation. Typically, methylation turns genes “off” and demethylation turns genes “on.”