Lecture28_patterns

Lecture28_patterns - Announcement Pattern formation during...

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1 Pattern formation during Development Bis2A Lecture 28 Announcement • No large overflow exam room available for our final • EVERYONE will be in here. – Move to the centers of the rows – Nearly every seat will be filled – Be sure to keep your eyes on your own exam! Dramatic New Discovery! • Yesterday (12/2/10) NASA announced the discovery of an organism with novel biochemistry • In the lab, can use arsenic in place of phosphorous – In DNA, RNA, NADH, ATP, etc – Presumably does the same in the wild – Thought to be an adaptation allowing the organism to live in a high arsenic environment – Bacterium found in Mono Lake, CA Scientists expected to find such an organism (eventually) • Why? Scientists expected to find such an organism (eventually) • Why? – Phosphorous and arsenic have similar chemical properties (same number of unoccupied orbitals) – Thus, they can perform the same fundamental functions within a cell
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2 • What element could organisms elsewhere in the universe use in the same way Earth’s organisms use carbon? How does a body get its shape? • What causes the formation of a distinctive shape (and symmetry) -- PATTERN FORMATION – During development, the cells in multicellular organisms must begin to organize to form a distinctive shape Figure 19.1 From Fertilized Egg to Adult (Part 1) All cells in the body are derived from a single zygote , and are genetically identical During embryonic development, they must assume different cell fates that will allow them to perform different functions in the adult organism. How does this happen? Development: from egg to adult Determination sets the fate of the cell. Cells in a multicellular organism all have the same genome; they differ from one another because of differential gene expression. In early embryos, every cell has potential to develop in many different ways. A cell’s fate , the type of cell it will ultimately become, is a function of differential gene expression and morphogenesis . Differentiation is the process by which different types of cells arise. Once a cell’s fate is determined, it must turn on a battery of genes
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Lecture28_patterns - Announcement Pattern formation during...

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