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Chapter 4 Blog: General Features of Cells (Kimberly)

Page history last edited by Kimberly Balao 13 years, 8 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


9/22/10: We had no phone polls today. We basically talked about the similarities and differences between eukaryotes and prokaryotes. They both have a place where they store their DNA and a plasma membrane. Often they vary in size too. Dr. Weber also stressed the idea that all cells are different because they express different proteomes. All cells are identical when it comes to genome, but he explained to us why there are different types of cells such as cardiac cells or neurons. He told us that the proteome can be affected by gene regulation, amount of protein or a frequency of a specific amino acid sequence. We talked a little bit of protein synthesis too, but it was basically review from our freshman year of bio. Lastly we talked about an experiment that wanted to track proteins and how they travel through their cell before they reached their destination. This experiment was called the pulse-chase experiment. In this experiment, they tracked down radioactive proteins in pancreatic cells. They chose the pancreas because the main function of the pancreas is to secrete proteins. But the jist of the experiment ended with the support that proteins are synthesized in the Rough ER before going anywhere else. 


9/24/10: Today, we touched upon the subject of protein trafficking. When proteins are made the first 20 amino acids or so contains the N-terminus which is targeted by the SRP (Signal Recognition Protein) which is basically the most important part of protein trafficking. SRP determines where the protein goes whether it be the rough ER, the cytoplasm or the semi-autonamus organelles (Mitochondria or Chloroplasts). To my surprise, i learned that SRP actually binds to the hydrophobic part of the protein. The N-terminus is an ER tagging sequence that is at the beginning of each amino acid sequence. Today we also talked about how if translation of a protein goes wrong and it loses its first 20 amino acids, it becomes dis-functional and the cell is at risk of becoming diseased. This happens because the N-terminus is at the beginning of the amino acid sequence, without it, the protein cannot go where it is destined to go and floats in the cytoplasm.  


B.  Useful Materials


http://www.scientificamerican.com/article.cfm?id=rare-victory-melanoma---> This article is about about biotechnology helped create a new drug that could people with advanced melanoma. They are hopeful that such a drug would be able to extend patients lives with advanced melanoma, who normally would live only a year after being diagnosed. In this study, they claimed that more than 60% of the patients with melanoma carried gene mutations that created a protein called "B-RAF". The mutations signaled a pathway that supported the growth of cancer cells. They began experimenting with this and created a new drug called PLX4032, the drug is fairly new and it is yet to show very promising results. 



This video talks more in depth about SRP. This video actually helped me a lot. The visual actually makes very good sense and elaborates on what Dr. Weber was talked about. So the SRP actually binds to the peptide AS translation is occurring. Then the SRP binds to its receptor in the ER and the ribosome making the protein binds to its receptor there also. The protein goes through a translocater on the outside of the ER membrane and translation occurs. When it is done, a signal peptidase actually cuts of the signal peptide.



http://www.ncbi.nlm.nih.gov/pubmed/17632513----> This article talks about how a genetic variation in Mon1a affects protein trafficking. They are trying to present evidence that Mon1a is is involved in the trafficking of ferroportin a major iron exporter in mammals. Differences in ferroportin actually relate to the differences in iron content in cells. 






Comments (1)

Derek Weber said

at 12:59 am on Nov 23, 2010

Good summary of SRP video.

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