Bis 104 etzler Q - Page 4

Bis 104 etzler Q - Page 4 - (D) The organelles in the...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: (D) The organelles in the pellet fro m step (C) were separated from one another by sedimentation equilibrium in a sucrose densit y gradient. Each of the above fractions was treated with detergent and then co mbined with ant ibodies against carboxypept idase Y, a vacuolar yeast protein. The immunoprecipitates fro m each fract ion were counted in a gamma counter and the cpm obtained for the immunoprecipitates fro m each fract ion at each time interval are listed in the table below. __________________CHASE TIME______________________ CELL FRACTION 5 min 10 min Cell medium Golgi Microsomes Mitochondria Vacuoles 0 100 24,800 0 0 0 22,000 100 0 0 15 min 0 2,114 27 0 23,500 25 min 0 53 0 0 24,857 Answer the fo llowing quest ions: a) How long does it take newly synt hesized carboxypept idase Y to reach the vacuo les? On the basis of the above data, name the organelles, in order, through which carboxypept idase Y passes from its site of synt hesis on the ribosomes en route to the vacuo les. b) Why was sucrose included in steps B, C and D above? 10. A patch of membrane containing b­adrenergic receptors and other relevant membrane proteins was pulled fro m a cell using a glass pipette, similar to the process used in a patch clamping technique. As shown in the diagram below, the external surface of the membrane is in contact with the solution in the pipette and the cytoplasmic surface o f the membrane is immersed in a small well. The well contains + + buffer that is equivalent to the salt composit ion (Mg +, Ca +, etc.) of the cytosol and contains ATP, but does not contain other small mo lecules such as other nucleotides. pipette ­ intact cell De mo pipette ­ ­ well outer solution inner solution ...
View Full Document

Ask a homework question - tutors are online