We covered pages 416-432 of the book, dealing with the properties that gene regulatory proteins have, mainly the fact that they can read the information in the DNA double helix without mamking direct contact with the bases, but by 'reading' chemical signals in the phosphodiester backbone unique to each nucleotide.
We also talked about the main structural motifs that are common to gene regulatory proteins (helix-turn-helix, zinc finger beta-sheet, leucine zipper, and helix-loop-helix).
We also covered pages 432-439, explaining how simple genetic switches work. They have been studied in bacteria and have the particularity that are composed by a single gene regulatory protein. We introduced the concepts of operon, operator, activator, and repressor.
Next class: Complex genetic switches (in eukaryotes), and post-trancriptional control
Quiz #13 Q&As:
1. In a multicellular organism what process ensures that the only proteins and RNAs to be produced in a particular cell are those that that particular cell (and, therefore, tissues and organs) requires?
Control of gene expression
2. In a multicellular organism most cells have all the information required to build a whole organism. Why does a cell “know” that only a fraction of the information must be used, and not all of it?
Control of gene expression
3. What is transcriptional control?
A mechanism through which gene regulatory proteins activate or repress trasncription of a gene
4. Mention two kinds of control of gene expression (other than transcriptional)
RNA processing, RNA transport and control, translational mRNA degradation, RNA editing, RNA differential splicing...
5. What is the difference between a simple genetic “switch” and a complex one?
In a simple one only one protein turns de gene on or off. In a complex one many proteins are involved, usually hundreds.
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