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 aka Chapter Summarization
Chapter 13, also known as the "unlucky chapter", was covered this week in Dr. Weber's General Biology II class. This chapter, rightfully named "Gene Regulation", is about, you guessed it, gene regulation! Basically, gene regulation is a cell process that involves regulating genes. You may be asking yourself "Why is this seemingly redundant chapter so important?" Well I'll tell you! Gene regulation saves time (and naturally money since time IS money), energy, resources, and lives. If a gene were left to go on willy-nilly then it would be transcribed multiple times, creating multiple mRNA strands. These mRNA strands would then go on to be translated in to many polypeptide strands. Polypeptide chains, as you know (or don't, but I hope you do), do stuff. Much of the time this stuff isn't needed. BAM! Cancer. You're dead. Thankfully, our cells can regulate their genes and only have select ones expressed at any one time. The way our eukaryotic cells regulate their genes is different than the way prokaryotic cells regulate their own, however.
Prokaryotic cells, like bacteria, have a relatively simple method of gene regulation. The gene is made up of a promoter region and the region that gets transcribed. When a repressor protein is not present an RNA polymerase enzyme attaches to the promoter region and then goes on its merry way, transcribing the DNA until it reaches the termination site. Sometimes activator proteins are present and make this process even faster!!! Bacteria also have areas called operons. These are genes located adjacently to each other that are regulated by one region, called the operator. This means that a single RNA polymerase transcribes one long mRNA strand that can code to several polypeptide chains. (This called a polycistronic mRNA) This one mRNA strand is translated by ribosomes at the same time!!!!!! Prokaryotic cells can instantly react to their environment. There are two types of controls, negative and positive. In a positive control, the gene is usually turned off, but is turned on when a small effector molecule appears. The opposite occurs in a negative control. Baddah Bing Baddah Boom, prokaryotic cells are really good at regulating their genes.
Eukaryotic cells are a little more complicated, but SO MUCH BETTER. You see, eukaryotic cells have this pretty little thing called "combinatorial control". This pretty much means that these cells can use more than one type of gene regulation at one time to fine tune the amount of regulation. Eukaryotes can do 5 things to regulate transcription: 1) Activator proteins can stimulate transcription; 2) Repressor proteins can inhibit transcription; 3) These activators and receptors can be modulated; 4) DNA chromatin can be unwound to expose certain genes; 5) DNA methylation can wind DNA tighter to hide certain genes. Eukaryotes have two important non-coding regions of nucleotides before the transcribed regions of DNA, the location of regulatory elements and the core promoter. The core promoter is also made up of two regions, the TATA box and the Transcriptional start site. The TATA box in a ddition to the Transcriptional start site determine exactly where the RNA Polymerase will attach and begin transcribing. The core promoter region has a low level of transcription. The regulatory site can either speed up or slow down the rate of transcription with activators or repressors, respectively. Through the power of proteins, like mediators, the activator and repressor proteins can greatly affect the rate of translation.
Eukaryotic cells can also regulate RNA processing and the translation of the proteins. The magical process of alternative splicing is also a process of gene regulation. A gene can be transcribed and then changed to a different polypeptide and so certain polypeptides are not expressed. This helps a lot with cell differentiation. Eukaryotic cells can also create short mRNA strands. These shorter strands can attach to longer strands and either force it to be degraded or just prevent it from being translated. These mRNA strands accomplish this by attaching to a complex and becoming part of the RISC. Lastly, some proteins can regulate mRNA strands and prevent them from being translated. These strands are continually transcribed, but not translated. When a small effector molecule is present it attaches to the regulatory protein and the mRNA is free to become translated.
Peace out. Word to your mother
B. Useful Materials
This video gives a quick overview of transcriptional regulation in eukaryotic cells. It then goes on to discuss the importance of said regulation in multicellular organisms, such as flies. In this video they used the HOX gene to describe the affects of mutations. Oh, and it happens to be a rap.
This animation is about the Lac Operon! It follows the beta-galactosidase and the permease being transcribed and later translated. The animation talks about how this stops, too. It does not show the CAP site, however, which is kind of lame.
Androgen Receptor Signalling in Prostate Cancer: The Functional Consequences of Acetylation.
This article talks about the consequences of acetylation in prostate cancer. This article says that Androgen Receptor recruits acetylation-modifiers when it enters the cell. This leads to the recruitment of histone acetyltransferaces. These proteins unwind the DNA and expose certain regions of it. This means that the androgen receptor is a key part in cancer progression.
Comments (1)
Derek Weber said
at 12:43 am on Feb 16, 2011
A Vanilla Ice quote is rare these days, well played.
Good job overall. Use the learning objectives as a guide as you write your summary.
If rhymes were drugs I'd sell them by the gram.....
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