LS23L final Exam Questions and Answers
with Verified Solutions | Latest Updated 2026
Why is it important to know including the cell density readings allow
the cell density at both the 20 us to normalize by cell density. This is
minute and 70 minute time important because the cells are actively
points? growing during this experiment, so there
will be more cells present at the 70
minute time point than there are at the 20
minute time point.
How would NOT knowing the If you didn't have the cell density
cell density affect your readings you might think that the increase
calculation of the Miller units? in b-gal activity at the 70 minute time
point is due to increased number of cells
(this is NOT TRUE, since we do normalize
for cell density!)
Based on your data, is the Yes, you should be able to see that b-gal
level of b-galactosidase activity is induced by lactose but not by
activity influenced by the type glucose.
of sugar present in the growth
medium?
, For the tube(s) that had high You should only see a high level of
levels of enzymatic activity, activity at the 70 minute time point. This is
did you see a high level of NOT due to increase in cells (see Q1). The
activity at the 20 minute time difference in b-galactosidase activity
point, the 70 minute time between 20 and 70 minutes reflects the
point, or both? time that it takes to induce b-
galactosidase synthesis after exposure to
lactose
In what direction is the reverse 5' to 3'
primer ("R") conventionally
read?
Which strand of the DNA (top Bottom
or bottom) will the forward
primer ("F") hybridize to during
the PCR reaction?
Will the DNA synthesized Top
starting from the forward
primer be the same sequence
as the top strand or the
bottom strand?
Will the DNA synthesized Bottom
starting from the reverse
primer be the same sequence
as the top strand or the
bottom strand?
with Verified Solutions | Latest Updated 2026
Why is it important to know including the cell density readings allow
the cell density at both the 20 us to normalize by cell density. This is
minute and 70 minute time important because the cells are actively
points? growing during this experiment, so there
will be more cells present at the 70
minute time point than there are at the 20
minute time point.
How would NOT knowing the If you didn't have the cell density
cell density affect your readings you might think that the increase
calculation of the Miller units? in b-gal activity at the 70 minute time
point is due to increased number of cells
(this is NOT TRUE, since we do normalize
for cell density!)
Based on your data, is the Yes, you should be able to see that b-gal
level of b-galactosidase activity is induced by lactose but not by
activity influenced by the type glucose.
of sugar present in the growth
medium?
, For the tube(s) that had high You should only see a high level of
levels of enzymatic activity, activity at the 70 minute time point. This is
did you see a high level of NOT due to increase in cells (see Q1). The
activity at the 20 minute time difference in b-galactosidase activity
point, the 70 minute time between 20 and 70 minutes reflects the
point, or both? time that it takes to induce b-
galactosidase synthesis after exposure to
lactose
In what direction is the reverse 5' to 3'
primer ("R") conventionally
read?
Which strand of the DNA (top Bottom
or bottom) will the forward
primer ("F") hybridize to during
the PCR reaction?
Will the DNA synthesized Top
starting from the forward
primer be the same sequence
as the top strand or the
bottom strand?
Will the DNA synthesized Bottom
starting from the reverse
primer be the same sequence
as the top strand or the
bottom strand?
