#* The spots show mostly a yellow color at the first time point because cells have not reacted to the environmental change (i.e. available oxygen). More time is needed to determine if transcription was induced or repressed; therefore, no change is indicated by the yellow color.

#* The spots show mostly a yellow color at the first time point because cells have not reacted to the environmental change (i.e. available oxygen). More time is needed to determine if transcription was induced or repressed; therefore, no change is indicated by the yellow color.

# (Question 10, p. 118)  Go to the [http://www.yeastgenome.org ''Saccharomyces'' Genome Database] and search for the gene TEF4; you will see it is involved in translation.  Look at the time point labeled OD 3.7 in Figure 4.12, and find the TEF4 spot.  Over the course of this experiment, was TEF4 induced or repressed?  Hypothesize why TEF4’s change in expression was part of the cell’s response to a reduction in available glucose (i.e., the only available food).

# (Question 10, p. 118)  Go to the [http://www.yeastgenome.org ''Saccharomyces'' Genome Database] and search for the gene TEF4; you will see it is involved in translation.  Look at the time point labeled OD 3.7 in Figure 4.12, and find the TEF4 spot.  Over the course of this experiment, was TEF4 induced or repressed?  Hypothesize why TEF4’s change in expression was part of the cell’s response to a reduction in available glucose (i.e., the only available food).

#*

#* Looking at Figure 4.12 and observing the TEF4 spot over the course of this experiment, I would conclude that TEF4 is being repressed since the TEF4 spot began at a yellow color that eventually turns to a bright and bright green color. TEF4 is responsible for ''stimulating the binding of aminoacyl-tRNA (AA-tRNA) to ribosomes''' (from [http://www.yeastgenome.org ''Saccharomyces'' Genome Database]). With the consumption of glucose over time and the increase of cell density, I would hypothesize that the cell is conserving energy for the expression of other genes. Within the slide of OD 3.7, an observation of GLK1 shows a red color meaning that this gene is being induced; therefore, the repression of TEF4 may give way to the induction of other genes within the ''Saccharomyces'' cell.

# (Question, 11, p. 120)  Why would TCA cycle genes be induced if the glucose supply is running out?

# (Question, 11, p. 120)  Why would TCA cycle genes be induced if the glucose supply is running out?

#*

#* TCA cycle genes would be induced if the glucose supply is running out because the cell is in need of glucose to run other cellular activity; therefore, the TCA cycle would produce oxaloacetate that can be converted into glucose through a metabolic pathway called gluconeogenesis.

# (Question 12, p. 120)  What mechanism could the genome use to ensure genes for enzymes in a common pathway are induced or repressed simultaneously?

# (Question 12, p. 120)  What mechanism could the genome use to ensure genes for enzymes in a common pathway are induced or repressed simultaneously?