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Lecture 10

BIO241 Lecture 10.doc

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Jennifer Harris

Thursday February 5 2009 So far weve been looking at movement within the cell how proteins move around the cell how membranes are formed its mainly been dealing with movement within the cell Todays lecturethe next ones will deal with cell communicationthis involves how does a cell perceive its extracellular environment It needs to stay in touch with its environmentrespond accordinglyYou can think of organisms into 2 major categories unicellular organisms that are made up of one cellthese organisms generally act on their own there may be communication bw the different unicellular organisms but they generally need to respond that one cell needs to respond to its extracellular environment so it needs to sense signals in the environment for example when its time to grow divide when the nutrients are good etcyou dont want to be reproducing when youre in an environment that might be too stressful for youyour offspring so unicellular organisms need to sense their environment what type of environment theyre inthen regulate their metabolism or their biology accordingly but that requires that that unicellular organism be able to perceive specific signals in the environment that indicate what type of environment its in Ex of unicellular organism yeast model organism Multicellular organisms have many different cell types The environment might be a cell type thats in your body for example In multicellular organisms the cell still needs to respond to differences in their extracellular environments but that extracellular environment might be within an organism or multicellular organism so the cells within an organism need to be very carefully regulated so they can benefit the entire organismwere going to see how different complex signaling networks can integrate multiple signals that are coming into a specific cell into a specific output so how does a cell perceive an extracellular signal Diagram This would be a plasma membrane with a specific receptorit detects a specific signal molecule on the outside of the cell this could be a hormone for example a neurotransmitter some type of nutrient in the environment or small molecule in the environmentthat perception of that signal needs to be transmitted to the inside of the cellthis is through signaling networksthen there needs to be the appropriate output from that organism in order to survive in that environmentthat might lead to altered metabolism to be able to use a certain nutrient in an environment altered gene expression to regulate the synthesis of specific proteins that are required in the environment or even alter the cell shape or the movement of specific cells
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