Skip to content
OperonBiology
Put in orderDifficulty 2/5 · StandardOlympiadRepresenting dataConcept explanation

Following the label out of the cell

Topic: Organelles & compartmentalisation

In the 1960s James Jamieson and George Palade gave slices of guinea-pig pancreas a 3-minute pulse of radioactive leucine, then a chase with ordinary leucine. The acinar cells in these slices make digestive enzymes for export. Samples were fixed at intervals over the next hour or two and autoradiography showed which compartments held the radioactive, newly made protein.

Experimental setup

Question
Which route do newly made secretory proteins take through the cell?
Independent variable
Time after the end of the pulse
Dependent variable
Location of radioactively labelled protein
Kept constant
Same tissue (guinea-pig pancreas slices) · Pulse length (3 min) · Excess unlabelled leucine in the chase
Groups
  • Pulse: 3 min with radioactive leucine
  • Chase: Unlabelled leucine; samples taken at increasing times

Put these compartments in the order in which most of the labelled protein reaches them, from the end of the pulse to secretion. The list combines what the autoradiographs showed with what is known today about the route.

Drag the items, or use the arrow buttons, so the first event is at the top.

  1. 1Mature secretory (zymogen) granules near the apical surface
  2. 2Cis face of the Golgi apparatus
  3. 3Lumen of the acinus, outside the cell
  4. 4Lumen of the rough endoplasmic reticulum
  5. 5Trans face of the Golgi apparatus
  6. 6Small transport vesicles between the ER and the Golgi

Ready when you are.