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Blog 14: Mutations

Page history last edited by Patrick Racine 13 years, 5 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

     In this chapter we discussed mutations and their effect on cells and DNA. A mutation can be simply defined as a change in DNA. These changes are typically small, but could potentially have major effects on cells. There are 3 basic types of mutations. Point mutations occur when there is a change in only one base pair in the sequence. Base substitutions occur when a single base in the DNA is exchanged with another base. There are three types of base substitutions: missense, silent and nonsense. Missense mutations occur when the base substitution causes a single amino acid in a polypeptide sequence to change. Silent mutations are gene mutations that do not alter the polypetide sequence, but rather the nucleotide sequence. Nonsense mutations occur when normal codons are changed to stop codons causing premature termination of transcription and ultimately the production of shorter polypeptides. Lastly, the final type of mutation is a frameshift mutation. This entails the removal or addition of nucleotides that are not in groups of three. This is the most harmful type of mutation. Mutations occur in both somatic cells and sex cells. When mutations occur in somatic cells, the mutation is not passed on to the offspring. However, when a mutation occurs in a gamete, then the mutation will be passed on.

     There are two types of DNA repair: direct and base/nucleotide excision repair. Direct repair involves enzymes finding incorrect DNA structures and coverting it back to its proper structure. Base/nucleotide excision involves the removal and repair of the damaged DNA region.

     Cancer is a disease characterized by uncontroallable cell division. Most cancers are caused by carcinogens, which are usually mutagens. Cancer derives from a single mutated cell in the organism and all of the cells that divided from it. In early stages, the mutated cells form tumors that are either benign or malignant (cancerous). If malignant tumors are left untreated, they will spread to other healthy parts of the body in process called metastasis. Tumor suppressor genes are genes that, when left unaffected by mutation, encode for proteins that prevent cancer.        

B.  Useful Materials

 

 

 

Comments (1)

Derek Weber said

at 12:36 am on Feb 16, 2011

no useful materials. Need way more detail in the chapter summary. Please see comments in chapter 13.

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