37 - Gene expression in eukaryotes

How many RNA polymerases do eukaryotes have? Prokaryotes?

Eukaryotes - 3

Prokaryotes - 1

Where is RNA polymerase 1 in eukaryotes? What does it code for?

Nucleolus, codes for ribosomal parts

Where is RNA polymerase II in eukaryotes? What does it code for?

Nucleoplasm, codes for mRNA and snRNA

Where is RNA polymerase III in eukaryotes, what does it code for?

Nucleoplasm, codes for tRNA and 5S ribosomal RNA

In eukaryotes, can promoters be located past the start of transcription?

Yes, they can be located dowstream of transcription start

Where does an activator bind?

To an enhancer sequence

Do eukaryotes have a sigma subunit in their RNA polymerase core?

No, only prokaryotes have it

What guides eukaryotic RNA polymerase to the start of transcription?

TFIID (transcription factor complex), which includes tata binding protein

What does TFIIH do?

phosphorylates carboxyl terminal of RNA pol II

What do TFIIB, E, and H do?

Dissociate from the transcription initiation complex

Which part of the transcription initiation complex remains as elongation proceeds?

TFIIF

What allows estrogen to enter the nucleus and activate transcription?

Dimerization of the receptor and bound estrogen allows it to enter nucleus, where the coactivator then binds and allows transcription to proceed

How does tamoxifen slow tumor growth?

It binds to estrogen receptors, preventing estrogen from binding

What property of histone tails allows them to interact with DNA?

They are rich in arginine, histidine, and lysine, granting them a positive charge and allowing them to interact with DNA, which has a negative charge

How does the addition of acetyl groups result in the activation of transcription?

Addition of acetyl groups reduces overall positive charge, which weakens charge-charge interactions in DNA

What is the template DNA strand for the mRNA sequence 5’-GCGGCCAUAU-3’

3’ - CGCCGGTATA-5’

or 5’- ATATGGCCGC - 3’

What specific complex binds to the TATA box?

TFIID, TBP specifically

Which molecule is a co-substrate for histone acetyltransferases?

Acetyl CoA