1. The diagram below illustrates the
growth of E. coli cells on a medium containing small amounts of both
glucose and lactose as the only C-sources.
(a) Which sugar (if any) is being utilized
during time A? Time B? Time C?
(b) In which
region(s) (A, B, C) is catabolite repression occurring?
(c) Is the intracellular concentration of
cyclic AMP high or low in region A? In region
C?
(d) Is lac repressor bound to DNA in region
A? B? C?
2. How do eukaryotes differ from
bacteria with respect to the following:
(a) size
of RNA polymerase?
__________________________
(b) rate of DNA
replication? ___________________________
(c)
frequency of introns?
____________________________
(d) coupling of
transcription/translation? _________________
(e)
organization of genes into operons? ___________________
Bonus Question: A cell mutates so that the gene coding for adenyl cyclase (the enzyme that converts ATP into cyclic AMP) is lost. Draw a graph similar to the figure in question 1 above that would accurately predict how this cell would behave in a medium containing both glucose and lactose.