Genetics Unit 14: Transcription

Transcribes all genes encoding for proteins in eukaryotic cells (messenger RNA). Also encode for some non-protein encoding RNAs (micro RNAs).

Encodes for ribosomal RNAs

Encode for small RNAs (tRNA and 5S of the ribosome).

Located aprox. 25 nucleotides upstream (5`) to transcription start site for a gene. Important for RNA Pol. II to recognize. (Not bound by actual pol. but by tata binding proteins which recruit RNA polymerase).

Located aprox. 75 nucleotides upstream (5`) to transcription start site for a gene. Important for RNA Pol. II to recognize. (Not bound by actual pol. but by caat binding proteins which recruit RNA polymerase).

DNA sequence that defines the position and direction of RNA polymerase initiation. (Located just upstream to the transcription start site.)

Biding sites for transcription factors which help recruit RNA polymerase to the promoter. Position and orientation independent. Can also be relitivley distant from trnascription start site and still work. All this is b/c DNA is flexible.

Sections of DNA which are not wrapped around histones. Associated with promotors and enhancers so RNA pol can find where to bind desptie all DNA being wrapped together. Is especially sensitive to DNA-ase 1 because of the lack of histone, hence the name.

Protein responsible for heat shock Pol II regulation. Normally sythesized but stored in a latent, monomeric state. Rise in temp triggers trimerization and binding upstream of a heat shock gene. Binding of HSF to to an enhancer increases transcription 100 fold.

Enables trimerization of HSF.

1) In absence of heat shock, HSF is a monomer and RNA polymerase is bound to a promoter and has transcribed a bit of RNA but is paused.
2) Heat shock triggers trimerization which allows binding of HSF to enhancer region.
3) HSF unpauses polymerase which clears promoter and begins RNA synthesis
4) This synth will encode for chaperone proteins which will protect proteins from heat-induced unfolding.

1) Normally, steroid receptor is bound to an inhibitory protein preventing interaction with other proteins.
2) Hormone diffuses through cell, binds receptor, displaces inhibitory protein.
3) Receptor and ligand travel into nucleus, portion of receptor folds into zinc fingers, and binds as a homodimer to its specific DNA target.
4) Leads to recruitment of basal transcription factors (like tata binding factor) which leads to RNA pol recruitment.
4)

Deletion of NDA 5' to all the different beta globin genes but results in the loss of expression of all of these genes. This is because the deletion removes the Locus Control Region (LCR) for all these genes.

Is an enhancer for multiple different promoters which lead to the transcription of different proteins. Which promoter is enhanced is based on which transcription factors are present. The genes without their transcription factors present are inactivated via methylation. Can change over time via different transcription factors being present.

Heterogenous nuclear ribonucleoprotein particles. Proteins which complexes with pre-mRNA in the nucleus.

Small nuclear RNAs which combine with proteins to form snRNPs.

Macromolecule machine which conducts pre-RNA splicing composed of several snRNPs.

Micro RNA. Transcribed by PolyII but do not encode for proteins. Instead the PolyII products are chopped into these miRNAs which have complementary base pairs to to a target mRNA (usually to an untranslated region between a stop codon and poly A tail).
Can down regulate mRNA or if seed region has complete base pair complimentarity, can cause mRNA to be degraded (RNA interference).

miRNA machinery