(image courtesy Pat Brown)
This experiment compared gene expression for yeast cells grown under two different conditions: constant supply of glucose and gradually decreasing supply of glucose.
In the raw data above, a red spot indicates a gene that has been induced and a green spot represents a gene that has been repressed.
RNA samples were obtained from the the growing cells at different time points as indicated by the increasing density of cells (in OD units).
1) Why would most spots be yellow at the first time point?
2) Go to Function Junction <http://genome-www.stanford.edu/cgi-bin/SGD/functionJunction> and look up TEF4. What role does the encoded protein play in the cell?
3) If you look at the frame from the time point labeled OD 3.7, you will see that TEF4 has been labeled. Over the course of this experiment, was TEF4 induced or repressed?
4) Can you hypothesize how the cell is responding to a reduction in available glucose (the only available food in this experiment)?
5) You can search other genes that have been labeled and deduce how the cell is responding to the gradual loss of food.
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