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Chapter 13 Blog: Gene Regulation (Maria)

Page history last edited by Maria Chiaffarano 13 years, 4 months ago

In the first section of this page, you will write a daily summary of that day's class.  For example in  your chapter 2 blog, your first entry should be titled 9/3/10.  You should then write a one or two paragraph summary of that day's lecture, outlining the major points.  In the second section, you are required to add two items (link to a website, video, animation, student-created slide show, student-created PowerPoint presentation) and one journal article pertaining to a topic in this chapter.  A one-paragraph summary must accompany each item describing the main idea and how it applies to the lecture topic.  Please see the PBWorks help guide for assistance embedding video and other items directly in the page.  I will also produce a how-to video on using tables to wrap text around items and other useful tips.  Please see the syllabus for organization and grading details.

 

A.  Daily Blog

Blog for 1/28/11 Lecture:

 

Gene Regulation

1) refers to the ability of cells to control their level of gene expression

2) majority of genes regulated so proteins produce at certain times and in specific amounts

3) Constituitive genes are unregulated adn ahve essentially constant levels of expression

4) Benefits of gene regulation:

     a) conserves energy - proteins produced when needed

     b) ensures genes expressed in appropriate type and at the correct stage in development

5) prokaryotes (no nucleus)

     a) used to respond to changes in environment

     b) E.coli and lactose example

6) Eukaryotes (have nucleus)

     a) cell differentiation

     b) same genome but express different proteomes

7) transcriptional regulation in bacteria

     a) involves regulatory transcription factors

     b) Kb and Ki

          1) Ki - rate of constant - rate of strand opening (DNA)

8) Constitutive genes - unregulated - good promoter regions - needed all teh time

9) Activator Proteins - enhance the binding and increase the rate, lowers activation energy

10) RNA polymerase has more affinity and faster - makes more proteins? when needed

11) Repressor protein - increase the binding constant; changes affinity adn ability to turn on the gene

 

Transcriptional Regulation

1) also involves small effector molecules

2) binds to regulatory transcription factor

3) 2 domains

 

Operons

1) operon in bacteria is a cluster of genes under transcriptional control of one promoter

2) allows regulation of a group of genes with a common function (only in prokaryotes)

3) In E.coli contains genes for lactose metabolism

     LacP - promoter and 3 structural genes

4) want them to be expressed when lactose is in the environment

     a)Near the lac promoter are 2 regulatory sites

     - lac O - operator - provides binding site for repressor proteins

     - Cap site - activator protein binding site (upstream)

     - Lac I gene - codes for lac repressor

 

Catabolic in nature - break down lactose

     E. Coli when lactose is absent - inactive

 

Trp Operon

   - encodes enzymes requried to make amino acid tryptophan

   - when trp is low, the repressor is inactive allowing the entire trp operon to be transcribed

 

Same principles in prokaryotes - activators and repressor proteins influence the ability to initiate transcription; regulated by small effector molecules

Differences : genes almost always organized individually and regulation is more intricate

 

Combinational Control

     - one or more activator proteins stimulate RNA polymerase to initiate transcription

      - Repressor - may inhibit

     - Binding of small effecotr molecules

     - Activator Proteins - promote loosening up the region in the chromosome where a gene is located (one X chromosome is kept silent in women)

 

TATA box

     - determiens where start site should be  

 

 

B.  Useful Materials

 

The Lac Operon (submitted 1/28/11)

http://www.sumanasinc.com/webcontent/animations/content/lacoperon.html

 

This site is very efficient and useful for learning about gene regulation and the lac operon.  It has animations and descriptions that are very important in the understanding of lac operons.  Prokaryotes and Eukaryotes both have different ways of metabolizing lactose.  The lac operon is found in prokaryotes and lactose is used to "turn on" or if it is absent, "turn off" certain genes. 

 

 

 

Youtube video: Lac Operon (submitted 1/30/11):

 http://www.youtube.com/watch?v=oBwtxdI1zvk

 

For some reason, this youtube video would not give me the Embed code but I copied and pasted it as a link.  It describes lac operons, the way they operate and why they are used.  It uses the famous example of E.coli and lactose. 

 

 

 

Pubmed Journal Article (submitted 1/30/11):

http://www.ncbi.nlm.nih.gov/pubmed/15332082

This article is one of the simplest I have ever found on Pubmed so I could not pass up the opportunity.  The topic is combinatorial control of genes and how it is crucial to understanding gene regulation.  Combinatorial control is multiple factors that take part in transcription.  Without understanding this concept, gene regulation would not make sense.  It also stresses protein and DNA regulators. 

 

 

 

Gene Regulation (submitted 1/30/11) :

 

 http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Promoter.html

 

The above website talks about gene regulation in Eukaryotes.  It starts out by giving the basic details about how all the cells in the body have the same genes or genome, but what makes cells different are that only certain genes are expressed.  Genes can be "turned on" or "turned off".  Several methods are used by eukaryotes, including the increasing or decreasing of the rate of transcription.  This alters the rate, ability, and efficiency of transcription.  Exons, introns, silencers, and enhancers also affect gene regulation.   

 

Comments (1)

Derek Weber said

at 11:59 pm on Feb 15, 2011

Nice job on the item summaries. When writing the chapter summary, use the learning objectives to guide you. Please summarize all of these objectives, whether we covered them in lecture or not.

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