Lecture_4,_2008

Lecture_4,_2008 - Bio 187, Fall 2008 Lecture 4, Sept 9...

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Bio 187, Fall 2008 Lecture 4, Sept 9 P ROTISTS AND THE E UKARYOTIC CELL The literature in the book is quite large for this section. Don’t panic – Know the basic phylogenetic relationships between the algae and the plants, as well as within the unikonts (as they relate to the tree shown in lecture). Don’t worry about the large list of different protests given in the table, but do make sure you understand the basic characteristics of our “highlighted” protests. They fall into different categories that illustrate diversity in ecology and complexity. Do read the sections on the infolding and endosymbiosis hypotheses more carefully – understand their basic arguments and how current data fit them. CH 27: 582-587 (for general info only); 588-590; 596-608 (emphasizing examples in class) E VOLUTION OF E UKARYOTES For simplicity, I’ve divided the Eukaryotes into 4 groups: Protists, Plants, Fungi, Animals. But these are no longer the “official” divisions. Genomic sequencing has produced a lot of new information on genetic diversification in this domain and as a result the phylogeny has gotten a lot more complicated. As evidence, the table on page xx. If we learn all of this in Bio 187, we will miss the major points needed to be made about the evolution of the Eukaryotes. So, we’ll look at only a few groups of protists as exemplars, and focus on some larger questions. These are: 1. What are the major defining characteristics of the Eukaryotic cell ? -its compartmentalization -the containment of chromosomes in a nucleus -the presence of certain organelles, particularly the mitochondrion 2. What is so special about compartmentalization? -it allows the cell to concentrate molecules where they are needed -it allows the cell to get bigger -it allows for more complexity - multicellularity 3. How did the compartmentalization of major organelles (mitochondrion, chloroplasts and nucleus) happen ? -the infolding hypothesis -the endosymbiosis hypothesis -there may be evidence that both were involved 4. How should we divide up the protists? -it looks like there are two functional groups -one contains the ancestral type for the Plantae -the other contains ancestors for the Fungi and the Animalia
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Compartmentalization and the Eukaryotes When we compared the Bacterial cell to a Eukaryote cell in class, one thing that jumped out right away is how much more complex and compartmentalized the Eukaryote cell is. Eukaryotes have an internal matrix that organizes the cell (cytoskeleton) and cellular organelles where processes such as metabolism or information (DNA) storage and utilization are concentrated. What are the benefits of compartmentalization? 1. Cell processes can be concentrated in local areas, including concentration of the molecules relevant for each process – everything in its place! This increases speed and efficiency , because the right molecules are more likely to contact each other for chemical reactions. 2. Concentrating molecules in the places they are needed reduces the diffusion time
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This note was uploaded on 01/07/2012 for the course BIO 187 taught by Professor Douglasgreen during the Fall '07 term at ASU.

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Lecture_4,_2008 - Bio 187, Fall 2008 Lecture 4, Sept 9...

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