Passage I
Figure 1 depicts some of the steps of protein synthesis in eukaryotes.
In yeast, the genes that are expressed at a given time depend on environmental conditions, such as the glucose
concentration in the environment.
Saccharomyces cerevisiae, a type of yeast, was grown for 12 hours on a growth medium containing glucose. The
transcription rates of 4 genes (Genes 1—4) were determined. The relative transcription rate (RTR) of each gene was then calculated using the following formula:
The results appear in Figure 2.
Figure 3 shows the glucose concentration of the medium during the experiment.
Figures 2 and 3 adapted from Joseph L. DeRisi, Vishwanath Riyer, and Patrick O. Brown,“Exploring the Metabolic and Genetic Control of Gene Expression on a Genomic Scale." ©1997 by the American Association for the Advancement of Science.
5. According to Figures 2 and 3, when the glucose concentration of the medium was 12 g/L, the RTR of Gene 4 was closest to which of the following?
Your Answer is
Correct Answer is B
Explanation
Look at figure 3 first, when the ordinate glucose concentration is 12, the abscissa is about 6.5 hr;
Back to figure 2, the abscissa corresponding to Gene 4 is 6.5, and the ordinate RTR is about 0.5