Final answer:
HSF1-GFP normally resides in the cytoplasm and under heat shock, it relocates to the nucleus. The correct answer to the question is A) Cytoplasm; Nucleus.
Step-by-step explanation:
Heat Shock Factor 1 (HSF1) and GFP under Normal and Heat Shock Conditions
In its inactive form, Heat Shock Factor 1 (HSF1) is located in the cytoplasm. Under normal conditions, HSF1 forms a complex with heat shock proteins such as HSP70, which keeps it in an inactive state. Upon exposure to stress conditions like heat shock, HSF1 dissociates from the heat shock proteins and translocates to the nucleus, where it can bind to heat shock elements (HSEs) in the DNA and activate the transcription of heat shock proteins.
When tagged with GFP (Green Fluorescent Protein), the mobility and location of HSF1 can be easily observed using fluorescence microscopy. Under normal conditions, HSF1-GFP can be predominantly seen in the cytoplasm. However, when cells are subjected to heat shock, HSF1-GFP relocates to the nucleus to perform its function.
Therefore, the correct answer to where HSF1-GFP normally resides, and then under heat shock is A) Cytoplasm; Nucleus.