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Biol168_10F_Lecture 2_27Sep2010

Biol168_10F_Lecture 2_27Sep2010 - Dr Morris Maduro UC...

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Dr. Morris Maduro, UC Riverside Biology 168 – 10F – Lecture 2, page 1 Lecture 2: Localized determinants, cell-cell signaling, types of development. Textbook: 2nd edition: p. 211; pp. 295-304; pp. 378-380. 3rd edition: 212-215; 390. Some figures in these notes are redrawn from Wolpert et al. (2nd edition). Anatomy of the Gene A quick review of the gene as a fundamental unit of heredity and function: Basal transcription machinery : Common to all expressed genes, the basal transcription apparatus drives a low level of expression in the absence of any other regulation. Transcription factors (TFs) : These provide the regulation – positive, or negative. Transcription factors generally have two domains: DNA-binding (sequence recognition at cis -acting sites) and effector domain (interacts with basal transcription apparatus to increase or decrease basal rate of transcription). In activating transcription, TFs can act by opening chromatin directly (e.g. by modifying histones), or recruiting other proteins that do so – i.e. generally by increasing access of the transcription apparatus to the DNA. In repressing transcription, TFs will do the opposite, decreasing access to the DNA by occluding activators, or causing modification of histones that results in a compaction of chromatin. We are going to see that each of these steps can be subject to regulation , which is important for achieving expression at the appropriate time and space – a requirement for the reproducibility of development. The other important aspect of this process is that it can interfered with experimentally. At the level of gene expression, a common way is to block expression of the mRNA.
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