Chapter 19-Control of Gene Expression in Eukaryotes

what is meant by differential gene expression

cells with the same genome will express different sets of genes, this will create different cell types, arrange cells into tissues, and coordinate activity

what is chromatin remolding

a method of gene regulation in eukaryotes, which involves the alteration of chromatin structure to allow or restrict access to DNA for transcription factors and RNA polymerase

what is RNA processing

a method of gene regulation in eukaryotes, involving the modification of pre-mRNA transcripts through capping, polyadenylation, and splicing to produce mature mRNA

what is mRNA stability

a method of gene regulation in eukaryotes, determines which mRNA will be blocked or degraded vs which portions will move onto to become mature mRNA

what is protein degradation

a method of gene regulation in eukaryotes, which controls the lifespan and functionality of proteins through processes like degradation

what is the structure of chromatin

complex of DNA wrapped around histone proteins, assembles into an octamer

what is an nucleosome

DNA and histone complex

one of the methods of chromatin alteration takes place is through DNA methylation, what happens in this process

methyl groups(CH₃) are added to C nucleotides, this is catalyzed by DNA methyltransferases

what does DNA methylation do

leads to condensing or “closing” of chromatin which inhibits transcription, when high methylation near promoters are present there is low levels of transcription, when low methylation near promoters there is increased transcription

one of the methods of chromatin alteration takes place is through histone acetylation, what happens in this process

acetyl groups (COCH3) are added to histone proteins, which is catalyzed by histone acetyltransferases(HATs), and removed by histone deacetylases(HDACs) and leads to a more relaxed chromatin structure that promotes transcription

what does histone acetylation do

acetylation leads to decondensed or “open” chromatin, makes DNA more accessible for transcription, which leads to increased gene expression

one of the methods of chromatin alteration takes place is through chromatin-remodeling complexes, what happens in this process

large enzyme complex that uses ATP to reshape chromatin, slides nucleosomes, or knocks histones off the DNA to make transcription more accessible

how does the state of chromatin remodeling impact transcription

the condensation state of chromatin determines where and if transcription can occur, each cell has different patterns of DNA methylation and histone acetylation

what is epigenetics

any mechanism of inheritance due to something other than changes in DNA sequence

how is epigenetic inheritance passed down

methylation/acetylation patterns are passed on to daughter cells during division, allowing for formation of specialized cells, also patterns can be altered by the environment

one of the methods of transcriptional control in eukaryotes is regulatory sequences such as promoter sequences that bind to RNAP, what is an example of this

the TATA box, recognized by TATA binding protein(TBP)

what is a promoter-proximal element

close to promoter, allow coordinated regulation of genes of the same type

what is a enhancer

far from promoter, bound by activator proteins to begin or increase transcription

what is a silencer

far from promoter, bound by repressor proteins to shut down transcription

what is a general transcription factor

a protein that binds to specific DNA sequences in the promoter region, facilitating the assembly of the transcription machinery and the initiation of transcription, not really involved in regulation

what is a regulatory transcription factor

a protein that binds to specific DNA sequences in enhancer/silencer regions, or promoter-proximal elements influencing the rate of transcription and regulating gene expression, specific for different typers of cells

what is the method of transcription initiation of chromatin remodeling in eukaryotes

transcriptional activator binds to enhancer, recruits chromatin remodeling complexes or HATs

what is the method of transcription initiation of exposure of promoter and regulatory sequences in eukaryotes

a region of DNA is exposed, including the promoter, promoter-proximal element, and other enhancers

what is the method of transcription initiation of assembly of proteins in eukaryotes

other transcriptional activators bind to exposed DNA, DNA is looped and activators bind to mediator(large protein complex that interacts with many TFs and recruits RNA polymerase for transcription)

what is the method of transcription initiation of RNA polymerase binds to core promoter

GTFs and RNAP assemble on mediator, RNAP binds to the core promoter, and transcription begins

how is RNA processing controlled by alternative splicing

the same primary transcript(pre-mRNA) can be spliced in different ways, the same gene can yield more than one mature mRNA

how is the post-translational modification of RNA processing controlled by protein degradation

proteins to be degraded are tagged with ubiquitin protein, allowing them to be recognized and broken down by the large complex proteasome