Regulation of gene expression in eukaryotes?

Answer 1

First A. = 'usually involves operons'.

2nd A. = 'No ... that is done by prokaryotes and is a much simpler way of organizing genetic switches and regulating expression.

Eukaryotes use a much more complex network involving the likes of enhancers, silencers, insulators, trans and cis acting sequences.

Trans acting sequences are sequences which code for particular proteins (like repressor proteins) which bind to operator regions etc.

Cis acting are sequences such as operator and promoter regions (usually bound by particular proteins such as repressors or RNAP/DNAP, transcription factors...) and control gene expression within a close proximity and usually found downstream from the operator/promoter.

Enhancers are sequences found way upstream from the promoter sequences. These are bound by activator proteins (rather than transcription factors like promoter sequences) and once bound form a loop like structure bringing the bound activator protein to transcription factors and polymerases bound at the promoter region up-regulating gene expression. Silencers work in a similar fashion but bind proteins down-regulating gene expression.

Methylation and acetylation of histone tails can bring about the regulation of gene expression. For example acetylation of the lysine residues in histone proteins will nullify the positive charges causing them to have a lower affinity for the negatively charged DNA molecules allowing RNAP and DNAP to associate easier causing up-regulation of gene expression. Methylation leads to hetero-chromatination (facultative hetero-chromatin - also formed through gene silencing from RNAi through siRNA molecules) leading to down regulation of gene expression.

Again gene expression can be controlled through the length of the pol-A tail added post-transcriptionally. The length usually determines the half life of the molecule (with a shorter tail causing the destruction of the mRNA a lot more quickly). Also within the 3'untranslated region (between stop codon and 3' end) targets the localization of an mRNA strand within the cytoplasm playing a small role in gene regulation.'

Answer 2

• mutations
• transcrtiption factors
• repressors
• operons
• which is it your pick but
• i out mutations for this
• one maybe im wrong
• who knows?

Answer 3

Alternative splicing. The exons cut away from the introns can be done in alternative sections that regulate what genes will be expressed. Regulatory genes that can make protein products that block or enhance the transcription process.

Answer 4

Regulation of transcription in the eukaryotes is as a result of combined effects of structural properties and interactions of proteins called the transcription factors.

Answer 5

Transcription