Flashcards in Control of Gene Expression in Eukaryotes Deck (16)
search for promoter and enhancer regions in the DNA
are within 25 basepairs of the transcription start site
are more than 25 base pairs away from the transcription start site.
allows for the control of one gene's expression by multiple signals
Modification of chromatin structure affects
the ability of transcriptional enzymes to access the DNA through histone acetylation (increases accessibility) or DNA methylation (decreases accessibility).
2 domains in Transcription factors
DNA binding domain
DNA binding domain
binds to a specific nucleotide sequence in the promoter region or to a DNA response element (a sequence of DNA that binds only to specific transcription factors) to help in the recruitment of transcriptional machinery.
allows for the binding of several transcription factors and other important regulatory proteins, such as RNA polymerase and histone acetylates, which function in the remodeling of the chromatin structure
The large distance between the enhancer and promoter regions for a given gene means
that DNA often must bend into a hairpin loop to bring these elements together spatially
tightly coiled DNA that appears dark under the microscope; its tight coiling makes it inaccessible to the transcription machinery, so these genes are inactive
looser than heterochromatin and appears light under the microscope; the transcription machinery can access the genes of interest, so these genes are active.
Remodeling of the chromatin structures
regulates gene expression levels in the cell
proteins involved in chromatin remodeling because they acetylate lysine residues found in the amino terminal tail regions of histone proteins.
Specific patterns of this can lead to increased gene expression levels.
Acetylation of histone proteins
decrease the positive charge on lysine residues and weakens the interaction of the histone with DNA, resulting in an open chromatin conformation that allows for easier access of the transcriptional machinery to the DNA
proteins that function to remove acetyl groups from histones, which results in a closed chromatin conformation and overall decrease in gene expression levels in the cell
involved in chromatin remodeling and regulation of gene expression levels in the cell.