GV3: Gene Transcription

Question 1

what are the transcription control elements

Answer 1

RNA polymerase

transcription factors

Question 2

what is the role of RNA polymerase in elongation

Answer 2

polymerase advances 3’ to 5’ down template strand, melting duplex DNA and adding rNTPs by growing RNA

Question 3

what are promoters

Answer 3

DNA sequence which determines the site of transcription initiation for RNA polymerase; composed of sets of conserved DNA sequences and present in DNA upstream of transcriptional start site

Question 4

what is the gene transcription process

Answer 4

driven by/ activation of transcription factors and accessibility of DNA
requires coactivator proteins to unwind DNA on chromatin

Question 5

what is the structure of chromatin

Answer 5

DNA & histone proteins

Question 6

what happens in histone acetylation

Answer 6

histone proteins contain many basic amino acids with positive charge
enables interaction with negatively charged phosphate backbone of DNA
acetylation blocks ability to bind DNA by masking positive charge
relaxes interaction of DNA with nucleosome

Question 7

what is heterochromatin

Answer 7

densely packed nucleosomes, condensed

not actively transcribed, deacetylated histones

Question 8

what is euchromatin

Answer 8

extended ‘beads on a string’ appearance

being actively transcribed, acetylated histones

Question 9

what is the generic model of molecular signalling

Answer 9

stimulus -> receptor -> cascades -> response

Question 10

what are some examples of stimuli in signal transduction

Answer 10

growth factor, hormone, chemokine, cytokine

Question 11

what are some examples of receptors in signal transduction

Answer 11

tyrosine kinase-linked, GPCR, ion channel

Question 12

what are some examples of cascades in signal transduction

Answer 12

kinase activation, phosphorylation, Ca, insitol phosphates, phospholipids

Question 13

what are some examples of responses in signal transduction

Answer 13

gene expression, migration, growth, development, secretion

Question 14

what is the process of transcription

Answer 14

1. ligand activates receptor
2. activation of intracellular signalling pathway (kinases and second messengers)
3. activation of inducible transcription factors
4. recruitment of coactivator proteins
5. unwinding of DNA in enhancer region
6. binding of inducible factors
7. looping of DNA
8. unwinding of DNA in upstream region
9. binding of constitutive factors
10. looping of DNA
11. coactivator enhances the binding of TBP to TATA box
12. cooperative binding of other basal factors and RNA polymerase II
13. unwinding of DNA and reading 3’ to 5’ DNA strand
14. synthesis of mRNA 5’ to 3’