The experiment shown in Figure 12.10 was done using cytoplasm. What could the investigators do to determine whether the regulatory molecule was present in the cytosol or in a cytoplasmic organelle?
A- Use radioactive isotope labeling to separate the organelles and cytosol from M-phase cells and microinject only the organelles into the frog oocytes
B- Use fluorescent labels to separate the organelles and cytosol from M-phase cells and microinject only the organelles into the frog oocytes.
C- Use differential centrifugation to separate the organelles and cytosol from M-phase cells and microinject only the organelles into the frog oocytes.
D- Use gel electrophoresis to separate the organelles and cytosol from M-phase cells and microinject only the organelles into the frog oocytes.
HYPOTHESIs: Cytoplasmic regulatory molecules control entry into M phase. NULL HYPOTHESIS: M-phase regulatory molecules are not in the cytoplasm or do not exist. EXPERIMENTAL SETUP: ,-M-phase cytoplasnm Interphase cytoplasm Microinject cytoplasm from M-phase cell into one frog oocyte and cytoplasm from interphase cell into another frog oocyte. PREDICTION: Only the oocyte injected with M-phase cytoplasm will begin M phase. PREDICTION OF NULL HYPOTHESIS: Neither oocyte will begin M phase. RESULTS Oocyte is driven into M phase (nuclear envelope begins to break down, spindle apparatus forms). Oocyte remains in G2 phase. CONCLUSION: M-phase cytoplasm contains a regulatory molecule that induces M phase in interphase cells.
