Chapter 19 regulation of gene expression in eukaryotes
activators and repressors may either bind to:
1. chromatin near the promotor regions 2. directly to transcription factors to enhance or inhibit initiation
a small number of genes are regulated by dna rearrangement which may lead to 2 things:
1. creation of a new gene from smaller gene fragments 2. loss of Dna sequences in somatic cells
cis-acting sequence is located on the same chromosome as the gene it regulates and consists of 3 things:
1. promoters 2. enhancers 3. silencers
repositioned nucleosomes make regions of the chromosome accessible to transcription regulatory proteins such as:
1. transcription aviators 2. the enzyme Rna polymerase
what are transcriptional factors that increase transcription initiation
activators
where are promoters located
adjacent to the genes they regulate
what removes introns and joins exons in varying combinations
alternative splicing
what involves repositioning or removal of nucleosomes on Dna
chromatin remodeling
_______ promoters have several start sites
dispersed
enhancers and silencers act on genes _______ from them
downstream
activators bound to enhancers form___________ which interacts with the transcription complex
enhanceosome
activator proteins bind at _______ DNA elements to increase transcription
enhancer
________ increases the level of transcription initiation
enhancers
_______ promoters have a specific transcription start site
focused
_________ loosens chromatin structure which promotes the initiation of transcription
histone acetylation
acetyl groups (CH3CO) are attached to postively charged lysines in histone tails in_______
histone acetylation
histone acetylation of the nucleosome is catalyzed by __________ and is associated with increased transcription
histone acetyltransferase enzymes (HATs)
example: humans in humans gene expression is responsible for making different cells such as
kidney cell, liver cell, muscle cell, RBC, and numerous others from the same genome
when is eukaryotic gene expression regulated?
many stages during transcription and translation
the addition of ________ can condense chromatin and is associated with decreased gene expression
methyl groups (CH3)
what can repress trancription by binding to transcription factors of DNA
methylation
what occurs most often on the cytosine of CG bond in DNA?
methylation
gene expression is essential for cell specialization in ________
multicellular eukaryotic organisms
the addition of ______ next to a methylated amino can loosen chromatin
phosphate groups (phosphorylation)
what plays an important role in regulating gene expression via alternative splicing
post transcriptional regulation
nucleotide sequences that serve as recognition sites for the transcription machinery
promoters
enhancers and silencers are located in the _______
regulatory region which is usually upstream of the promoter region
what are transcriptional factors that decrease transcription initiation
repressors
repressor proteins bind at _____ DNA elements to repress transcription
silencer
________ repress the level of transcription initiation
silencers
what requires binding of many regulatory factors to specific dna sequences (cis-acting sequences)
transcription regulation
