Chapter 8 - Gene expression dictates cell identity = cell...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Gene expression - dictates cell identity = cell differentiation - all cells carry the complete genome but express different parts of it - how does a cell determine which genes to express? - general mechanisms are conserved but there is a lot of diversity in the specifics Central Dogma: DNA to RNA to Protein any step in this process can be (and is) regulated: Regulation of trxn initiation is a major regulatory step. Housekeeping genes: common to all cell types general function (metabolism, ribosomal proteins, chromatin proteins, DNA repair, splicing etc) less regulation - constitutive levels Cell-specific gene expression - defines cell type, regulates when, where and how expressed changes in TIME (e.g. develop stages, age) & SPACE (organ type and where in organ) e.g. kinases, acetylation etc
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 internal ” regulation - developmental/differentiation signals external ” regulation - respond to other cells, hormones, environment - INDUCE or SUPPRESS expression - switch genes ON or OFF -access DNA sequence via major (or minor sometimes) groove (can also have less specific interactions with phosphate backbone) - bind to specific regions of DNA: recognizes specific bases in dsDNA - 20+ weak contacts = some generic to phosphate backbone, others specific to bases - together = specific selective binding with high affinity/specificity. Gene Regulatory Proteins Base pairs have asymmetric distribution of reactive groups allows asymmetric interactions - e.g. H-bonds allows Gene regulatory proteins to distinguish between bases and/or base pairs. 90
Background image of page 2
3 Gene regulatory Proteins: Common DNA binding motifs allow them to act as ON & OFF switches A. Homeodomain - three linked alpha-helices fit into major groove and make specific contacts with various classes of genes. C. Zinc-finger domain -an alpha-helix and beta-strand co- ordinate Zn binding = one finger usually in clusters of 3+ fingers sit in major groove like finger making contact with bases. B. Helix-turn-helix motif two a-helices with a random coil in between one helix sits within major groove and allows side chains to make specific contact with bases D. Leucine-zipper -a coiled-coil interaction (hydrophobic via Leu residues) allows two a- helices to interwine
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/02/2008 for the course BIO 2600 taught by Professor Vanburkem during the Winter '08 term at Wayne State University.

Page1 / 12

Chapter 8 - Gene expression dictates cell identity = cell...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online