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Chapter 14 Blog: Mutations (Maria W)

Page history last edited by Maria Waterhouse 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

 

14.1: Genetic mutations are defined as small changes in DNA structure that alter a particular gene. Though the change is small, the gene that is altered varies dramatically in importance. The changes to the gene can either be that a base sequence within a gene is changed, or one or more nucleotides can be added to or removed from a gene. These different types of mutations cause different reactions, and sometimes they can cause no change at all. If a base is changed in a very important region of the gene, the proteins encoded could change. Mutations can also be located in noncoding sequences and still affect gene expression, such as in the promoter region, splice junctions, operator site, etc. A mutation in each of these places has a different affect on the gene expression. Sometimes, gene expression can be increased, while other times it can be decreased or stopped entirely. 

     Mutations can be spontaneous or induced. A spontaneous mutation results from abnormalities in biological processes, and the organism would have no ability to change the mutation. Induced mutations are caused by environmental agents that enter the cell and alter the structure of DNA. They can usually be stopped, and such agents are called mutagens. 

 

14.2: DNA repair is essential for minimizing occurrences of mutation. Proteins play a role in repairing the abnormalities. There are three common types of DNA repair systems; direct repair, base excision and nucleotide excision repair, and methyl-directed mismatch repair. Direct repair recognizes an abnormality in the DNA and directly changes it back to a correct structure. Base excision and nucleotide excision repair involves removing a portion of the strand containing the abnormality and using the template strand to make a normal DNA strand. Methyl-directed mismatch repair is similar to base nucleotide excision except that it's a base pair mismatch, not a an abnormal nucleotide.

 

14.3 Cancer is a disease of multicellular organism characterized by uncontrolled cell division. Carcinogens are agents that increase the likelihood of developing cancer, such as UV light and cigarette smoke. Tumors are an early form of overgrowth of cells, and they can be benign or malignant, the latter being the more serious of the two. Oncogenes and tumor-supressor cells are a big part of cancer control. Oncogenes are mutant versions of proto-oncogenes that contribute to overgrowth of cells, whereas tumor-supressor cells are normal and encode a protein that helps prevent cancer.  Oncogenes promote cell division, by keeping the cell in the permanent "on" position and can affect many different proteins.  Some cancers are caused by viruses, and can affect the checkpoints in the cell division cycle. 

 

B.  Useful Materials

 

This video is of two different types of cells; normal, and cancerous. The cancer cells divide much faster than the normal cells, as we talked about it class, and that is shown here in this video.

 

This video describes the missmatch repair of DNA. We discussed this is class, and this video clearly shows which enzymes are used and what each protein does.

 

http://www.nature.com/emboj/journal/vaop/ncurrent/full/emboj201110a.html

This PubMed article discusses how, by using nucleotide excision repair, scientists are able to regulate DNA division at the checkpoints more accurately. The DNA checkpoints were altered by radioactivity, and so researchers injected genes that could be expressed that would increase checkpoint activity. 

Comments (1)

Derek Weber said

at 12:49 am on Feb 16, 2011

Be a bit more descriptive in your item summaries.

Use the learning objectives as a guide when writing the chapter summaries.

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