Please explain your answers 7. Cells must maintain an appropriate level of fluid
ID: 202255 • Letter: P
Question
Please explain your answers
7. Cells must maintain an appropriate level of fluidity across their membranes. Hot temperatures lead to greater membrane fluidity. What might you then expect to find regarding the membrane composition of bacteria from very hot environments? You have a cell with a fluorescently labeled lipid in equal abundance on the inner and outer leaflets of the cell membrane. You then photobleach an area of membrane of this cell. What will happen next to the bleached area? 9. Phospholipid vesicles are made with two secondary transporters in their lipid bilayers: a sodium/calcium symporter and a sodium/potassium antiporter. The solution on the interionr of the vesicles contains 100 mM NaCl and 50 mM Cach. The vesicles are then placed in a solution containing 50 mM NaCl and 50 mM KCl. What will be the initial flow of ions into or out of these vesicles? 2 10. Grb-2 is a key adaptor protein in EGF signaling. What is the function of Grb-2 in EGF signaling? 11. What are the general properties of trimeric G-proteins? Of monomeric G-proteins? 12. An insulin receptor that is always a dimer is MOST LIKELY to cause what change in insulin signaling? 13. What is a zvmogen?Explanation / Answer
1) The fluidity of the cell membrane in thermophiles is maintained by the presence of thermophilic lipids with unique structural characterstics. But, a single lipid by itself is not responsible for the thermophilic ablility of the bacteria. The ether bonds of archaeal lipids are not broken down under conditions in which ester linkages are completely methanolyzed, So it is believed that the archaeal ether lipids are heat resistant, whicj maintains the fluidity of the cell membrane.