The graph below shows a growth curve of E. coli growing in a defined medium containing equal molar amounts of glucose and lactose.
 - Word.jpg)
Based on your knowledge of the regulation of the lac operon, the best explanation of these results is that
A) early on, due to the presence of lactose, the bacteria utilize the lac operon. Glucose is used later.
B) the bacteria are utilizing both sugars simultaneously.
C) the presence of glucose causes the formation of cAMP catabolic repressor protein (CRP) complexes, which shut down the lac operon until the glucose is used up.
D) glucose is used first. Once glucose becomes limiting, intracellular cAMP increases, forming cAMP-CRP complexes that activate the lac operon to use lactose.
E) none of the above
D) glucose is used first. Once glucose becomes limiting, intracellular cAMP increases, forming cAMP-CRP complexes that activate the lac operon to use lactose.
You might also like to view...
Which of the following is the best example of how we can separate the effects of genes and the environment on the expression of a complex trait?
A. About 80% of an individual's height is determined by genes and 20% by environment. B. For identical twins raised in the same environment, height should not differ by more than 20%. C. In a group of individuals of the same sex, about 80% of the variation in height among individuals is due to genetic differences and 20% is due to environmental differences. D. If one individual is 60 inches tall and another is 70 inches tall, they differ in about 80% of their genes. E. None of these choices accurately illustrate how we can separate the effects of genes and the environment on the expression of a complex trait.
The metal atom bound to the heme group of hemoglobin is
A. sodium. B. copper. C. zinc. D. iron. E. manganese.
Gene flow can either speed or slow adaptation, depending on whether beneficial or deleterious alleles enter a population
a. true b. false
Asbestos is a material that was once used extensively in construction. One risk from working in a building that contains asbestos is the development of asbestosis caused by the inhalation of asbestos fibers. Cells will phagocytize asbestos, but are not able to degrade it. As a result, asbestos fibers accumulate in _____.
A) mitochondria
B) ribosomes
C) peroxisomes
D) lysosomes