BIO 201 Lecture Notes - Lecture 8: George Emil Palade, Endoplasmic Reticulum, Secretion
18 Feb 2017
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Sheets of membrane covered with blobs (ribosomes) Ribosomes are on outside of rough er. Not interconnected with er, but similar structure. Divided into cis- (nearest to er and nucleus), medial (middle), and trans- (nearest to plasma membrane) stacks. Vesicles fusing or budding off of golgi. Produce and secrete copious amounts of digestive enzymes in rough er. Secretory proteins hung out in secretory granules (vesicles) Label newly-synthesized proteins with radioactive isotopes and watch labeled. Track proteins through cell until they were secreted. New proteins synthesized aren"t radioactive after radioactivity is washed out. Labeled proteins should be found in different organelles at regular time intervals after labeling. 1-3 min later: radioactive proteins are near rough er. 10-20 min later: radioactive proteins in golgi. 120+ min later: radioactive proteins over secretory vesicles then going out of cell membrane. Rer drops quickly since you"re labelling in a very small time frame. After 120+ min, proteins are still stuck in secretory vesicles.
