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.
1. At which of the following times was the transcription rate of Gene 2 the greatest?
Your Answer is
Correct Answer is D
Explanation
Look at figure 2, the slope of the line segment of Gene 2 is larger than before at 6 hr, so the transcription rate is larger at this time