rav65819_ch16_303-324

rav65819_ch16_303-324 - ; part III 16 genetic and molecular...

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

View Full Document Right Arrow Icon
;;;;;;;; part III 16 genetic and molecular biology 40 mm 40 m μ chapter
Background image of page 1

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

View Full DocumentRight Arrow Icon
IN MUSIC, DIFFERENT INSTRUMENTS PLAY their own parts at different times during a piece; a musical score determines which instruments play when. Similarly, in an organism different genes are expressed at different times, with a “genetic score,” written in regulatory regions of the DNA, determining which genes are active when. The picture shows the expanded “puff” of this Drosophila chromosome, which represents genes that are being actively expressed. Gene expression and how it is controlled is our topic in this chapter. Control of Gene Expression introduction 16.5 Eukaryotic Chromatin Structure Transcription factors can be either general or speciFc Promoters and enhancers are binding sites for transcription factors Coactivators and mediators link transcription factors to RNA polymerase II The transcription complex brings things together 16.4 Eukaryotic Regulation concept outline 16.1 Control of Gene Expression Control usually occurs at the level of transcription initiation Control strategies in prokaryotes are geared to adjust to environmental changes Control strategies in eukaryotes are aimed at maintaining homeostasis 16.2 Regulatory Proteins Proteins can interact with DNA through the major groove DNA-binding domains interact with speciFc DNA sequences Several common DNA-binding motifs are shared by many proteins 16.3 Prokaryotic Regulation
Background image of page 2
Control of transcription can be either positive or negative Prokaryotes adjust gene expression in response to environmental conditions The lac operon is negatively regulated by the lac repressor The presence of glucose prevents induction of the lac operon The trp operon is controlled by the trp repressor Both DNA and histone proteins can be modiFed Some transcription activators alter chromatin structure Chromatin-remodeling complexes also change chromatin structure 16.6 Eukaryotic Posttranscriptional Regulation Small RNAs can affect gene expression Alternative splicing can produce multiple proteins from one gene RNA editing alters mRNA after transcription mRNA must be transported out of the nucleus for translation Initiation of translation can be controlled The degradation of mRNA is controlled 16.7 Protein Degradation Addition of ubiquitin marks proteins for destruction The proteasome degrades polyubiquitinated proteins 303 rav65819_ch16_303-324.indd 303 rav65819_ch16_303-324.indd 303 11/17/06 4:11:33 PM 11/17/06 4:11:33 PM 16.1 Control of Gene Expression Control of gene expression is essential to all organisms. In prokaryotes, it allows the cell to take advantage of changing environmental conditions. In multicellular eukaryotes, it is critical for directing development and maintaining homeostasis. Control usually occurs at the level of transcription initiation
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 10/15/2010 for the course BIO BIO1 taught by Professor Lipke during the Fall '09 term at CUNY Brooklyn.

Page1 / 64

rav65819_ch16_303-324 - ; part III 16 genetic and molecular...

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