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Chapter 4 Blog: General Features of Cells (John T)

Page history last edited by John Tamanas 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

9/22/2010: Captain's log. Bio-lecture day 6. We began our expedition across the vast lands of chapter 4. We began the discussion by first going over the differences between prokaryotes and eukaryotes. Prokaryotes are cute little cells that have a cell wall, but no endomembrane system. It is like a warehouse because everything is in just one "room". Eukaryotes, on the other hand, are big cells. Unlike the prokaryotes, eukaryotes have an endomembrane system and even have semiautonomous organelles. Eukaryotes are much like a city. It has specific "buildings" for power, information, cleanup, and many other things. We then went on to discuss the translation of proteins. When a protein is being translated 1 of two things can occur. The ribosome can either stay in the cytosol or attach itself to the ER halfway through translating. What happens all depends on trackers embedded in the polypeptide chain. We finished the discussion with the experiment of how proteins moved from the ER, to the Golgi, out of the cell. The scientists injected a pancreas with an isotope of sulfur and then with the normal nutrients and watched how the cell created proteins in the ER, transported them to the Gogli, and then transported them out of the cell. It was so cool! Captain out.


9/24/2010: Captain's log. Bio-lecture day 7. Class began with a discussion of protein trafficking. Protein trafficking is basically where a protein goes before, during, and after translation. In most, if not all cases, proteins start in the cytoplasm. Then, depending on the presence or lack of presence of a protein signaling sequence the protein can be released in the enzyme, pause translation and move to the rough ER, or continue translation and move to a semi-autonomous organelle. If the protein signal sequence tells the ribosome to send it to the rough ER, the SRP, signal recognition particle, then binds to the signal sequence and attaches it to the rough ER. The SRP then leaves the protein and ribosome attached to the rough ER where it will continue translation. In most cases, the protein moves to the golgi where it will be modified further and then released to where it needs to go. This stuff is pretty interesting. Captain out.


B.  Useful Materials


Submitted 9/27/2010:   http://www.ncbi.nlm.nih.gov/pubmed/20862215


From what I understood from the article, these scientists discovered the trafficking of APL-1(amyloid precursor-like protein). They also found that this is helpful in understanding the role of APL-1.



BACKGROUND: Alzheimer's disease (AD) is a neurodegenerative disorder primarily characterized by the deposition of β-amyloid plaques in the brain. Plaques are composed of the amyloid-β peptide derived from cleavage of the amyloid precursor protein (APP). Mutations in APP lead to the development of Familial Alzheimer's Disease (FAD), however, the normal function of this protein has proven elusive. The organism Caenorhabditis elegans is an attractive model as the amyloid precursor-like protein (APL-1) is the single ortholog of APP, and loss of apl-1 leads to a severe molting defect and early larval lethality.

METHODOLOGY/PRINCIPAL FINDINGS: We report here that lethality and molting can be rescued by full length APL-1, C-terminal mutations as well as a C-terminal truncation, suggesting that the extracellular region of the protein is essential for viability. RNAi knock-down of apl-1 followed by drug testing on the acetylcholinesterase inhibitor aldicarb showed that loss of apl-1 leads to aldicarb hypersensitivity, indicating a defect in synaptic function. The aldicarb hypersensitivity can be rescued by full length APL-1 in a dose dependent fashion. At the cellular level, kinesins UNC-104/KIF-1A and UNC-116/kinesin-1 are positive regulators of APL-1 expression in the neurons. Knock-down of the small GTPase rab-5 also leads to a dramatic decrease in the amount of apl-1 expression in neurons, suggesting that trafficking from the plasma membrane to the early endosome is important for apl-1 function. Loss of function of a different small GTPase, UNC-108, on the contrary, leads to the retention of APL-1 in the cell body.

CONCLUSIONS/SIGNIFICANCE: Our results reveal novel insights into the intracellular trafficking of APL-1 and we report a functional role for APL-1 in synaptic transmission.



Submitted 9/27/2010:    oembed errorPlugin error: This URL is not valid for embedding: http://www.youtube.com/watch?v=rvfvRgk0MfA


This video is a quick overview of protein trafficking. It shows proteins moving from the rough ER to the Golgi and how they are being sorted there. 



Submitted 9/27/2010:



This website goes over the differences between prokaryotes and eukaryotes. It even has a cute story discussing the formation  of a mitochondria. 


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