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Chapter 4 Blog: General Features of Cells (Larissa)

Page history last edited by Larissa-Helen Mahaga-Ajala 13 years, 2 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: This lecture's focus was the cell and its structures.  First, prokaryotic cells were discussed.  This type of cell has no organelles, no nucleus, is smaller than the typical eukaryote, and have cell walls.  There are two types of prokaryotes: Archaea and Bacteria.  Both are small however they have key differences.  Bacteria is abundant and most bacteria is not harmful.  (There is still some mystery surrounding bacteria.  Only 1-3% of bacteria has been identified.)  Archaea is less common and often found in extreme environments.  Next, the eukaryote was discussed.  The eukaryote has a nucleus and is compartmentalized with the help of organelles.  Organelles are membrane-bound compartments with their own unique structure and function.  The shape, size, and organization of cells vary considerably among different species, and even among diffeent cell types that are of the same species.  Then, proteomes were discussed.  Proteomes determine the cell characeristics.  All cells have the same DNA but different proteomes and expression.  Gene regulation, amount of protein, amino acid sequence of a particular protein, and protein modification can influence the cell's proteome.  The proteomes in cancerous cells are different from those in a healthy cell.  Subsequently, translation was discussed.  Translation is polypeptide synthesis, which is mediated by ribosomes.  Two types of RNA are mRNA and tRNA.  tRNA is concerned with quality control.  Then, the endomembrane system was covered.  Its goal is to keep everything out of the cytoplasm, therefore it must act as a shuttling system.  The nucleus, ER, Golgi, lysosomes, vacuoles, plasma membrane, and vesicles are part of the endomembrane system.  The two types of ER were then discussed: rough and smooth ER.  Rough ER does protein synthesis and is studded with ribososomes.  Smooth ER is used for detoxification and the production of lipids.  Lastly, he Golgi apparatus was discussed.  The Golgi apparatus is a stack of flattened, membrane-bounded compartments.  It is used for the secretion and processing.  It is not continuous, therefore vesicles transport materials between sacs.  This organelle is dynamic because it is constantly being rebuilt and broken down.  The cis side of the Golgi is where it accepts, but the trans side is the exit point. 


9/25/10: In this class, the fate of newly synthesized proteins was discussed.  The proteins end up in the cytosol, undergo co-translational sorting to the ER, or undergo post-translational sorting to other organelles.  During co-translational sorting, DNA in the nucleus undergoes transcription.  The end product is transported to the rough ER during translation.  For co-translational sorting to occur, the protein has an ER signalling sequence at N-terminus that is targeted by signal recognition proteins (SRP).  The ER signalling sequence is made up of 20 amino acids.  The SRP guides the protein to the channel protein.  Then signal sequence falls off.  Without the N-terminus, diseases like cystic fibrosis can occur.  In cystic fibrosis, the protein without its N-terminus floats around the cell doing nothing.  An abundance of these useless proteins floating around causes the cell to become hypertonic and soak up lots of water.  


B.  Useful Materials

Cis-regulatory mutations in human disease http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2742803/pdf/elp021.pdf

This journal article is basically about the role cis-regulatory genes play in gene mutation.  Single nucleotide polymorphisms (SNPs) that are found in non-coding genomes are associated with these mutations.  Beta thalassemia, hemophilia, and atherosclerosis are a good examples of diseases caused by cis-regulatory mutations.  The possibility for people to get different genetic diseases is caused by people having different genes.   


http://www.youtube.com/watch?v=H5udFjWDM3E This is a video excerpt from a NOVA Special called RNAi.  It includes an analogy of how protein synthesis occurs in the cell.  It's pretty short and actually simplifies the entire process.  


http://www.funtrivia.com/playquiz/quiz14606510ba900.html This link is an online quiz for the structure of the animal cell.  There are only ten questions and though they may seem simple, without some of this information, understanding biology will be very difficult.  

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