201hw5 - Biology 201. Homework, Chapter 8 1. You go to buy...

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Biology 201. Homework, Chapter 8 1. You go to buy tomatoes at the supermarket, and find several that are mushy. The person you’re shopping with wonders out loud, “I wonder what makes tomatoes mushy”. What’s your explanation, focusing on the molecular level? Pectin is a polysaccharide present in cell walls and middle lamella of plants. In the middle lamella, it helps bind cells together. Bacteria each pectin, weakening the bonds between cells and making the tomatoes mushy. 2. Imagine that someone is born with a mutation making them deficient in integrin proteins. What problems exactly would this cause in terms of the extracellular matrix? Be specific. Name specific cells/proteins/other molecules that might be impacted and how. Integrins are intermembrane proteins that link inner cell components like actin to components in the extra cellular matrix like fibronectin. They mediate cell-to-cell interactions and communications and help link cells. Reducing the number of integrins would make cell connections “looser”, and this could result in more space between cells. Concentrations of ECM components would then decrease, meaning ECM reactions would take longer and messages sent to cells throughout the ECM would take much longer to reach their destinations. Furthermore, cells would be less able to receive messages. 3. In epithelial cells of the intestine, there are active glucose transport proteins on the side of the cell facing the intestinal lumen that transport glucose into the cells. On the side facing the underlying capillary beds there are facilitated glucose transporters that move glucose from the cells to the blood. These epithelial cells are connected by tight junctions. Remembering that the membranes are “fluid” and that proteins can move in the lipid bilayer, why are the tight
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This note was uploaded on 04/26/2011 for the course BIO 201 taught by Professor Hofkin during the Spring '06 term at New Mexico.

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201hw5 - Biology 201. Homework, Chapter 8 1. You go to buy...

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