Mutations in the dnaA gene of E. coli are lethal. Therefore, we can only study such mutations if we are able to generate conditional mutations (mutations whose effect takes place only in certain conditions). One type of conditional mutation manifests the mutant phenotype at high temperatures and is thus called a temperature-sensitive mutation. Temperature-sensitive dnaA mutants grow and replicate their DNA at the permissive temperature of 25°C, but they do not grow or replicate their DNA at the restrictive (non-permissive) temperature of 37°C. Two observations helped to determine the function of the dnaA gene product: • First, in vitro studies using DNA templates that have been unwound do not require the DnaA protein for DNA synthesis. Second, if intact cells are grown at 25°C and then shifted to 37°C, DNA synthesis continues at this temperature until one round of replication is completed, and then DNA synthesis stops. a. What two conclusions can you draw from these observations about the role of the dnaA gene product? b. Explain your answers.

Human Anatomy & Physiology (11th Edition)
11th Edition
ISBN:9780134580999
Author:Elaine N. Marieb, Katja N. Hoehn
Publisher:Elaine N. Marieb, Katja N. Hoehn
Chapter1: The Human Body: An Orientation
Section: Chapter Questions
Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...
icon
Related questions
Topic Video
Question
Mutations in the dnaA gene of E. coli are lethal. Therefore, we can only study such mutations if
we are able to generate conditional mutations (mutations whose effect takes place only in certain
conditions). One type of conditional mutation manifests the mutant phenotype at high
temperatures and is thus called a temperature-sensitive mutation. Temperature-sensitive dnaA
mutants grow and replicate their DNA at the permissive temperature of 25°C, but they do not
grow or replicate their DNA at the restrictive (non-permissive) temperature of 37°C.
Two observations helped to determine the function of the dnaA gene product:
• First, in vitro studies using DNA templates that have been unwound do not require the
DnaA protein for DNA synthesis.
Second, if intact cells are grown at 25°C and then shifted to 37°C, DNA synthesis
continues at this temperature until one round of replication is completed, and then
DNA synthesis stops.
a. What two conclusions can you draw from these observations about the role of the dnaA
gene product?
b. Explain your answers.
Transcribed Image Text:Mutations in the dnaA gene of E. coli are lethal. Therefore, we can only study such mutations if we are able to generate conditional mutations (mutations whose effect takes place only in certain conditions). One type of conditional mutation manifests the mutant phenotype at high temperatures and is thus called a temperature-sensitive mutation. Temperature-sensitive dnaA mutants grow and replicate their DNA at the permissive temperature of 25°C, but they do not grow or replicate their DNA at the restrictive (non-permissive) temperature of 37°C. Two observations helped to determine the function of the dnaA gene product: • First, in vitro studies using DNA templates that have been unwound do not require the DnaA protein for DNA synthesis. Second, if intact cells are grown at 25°C and then shifted to 37°C, DNA synthesis continues at this temperature until one round of replication is completed, and then DNA synthesis stops. a. What two conclusions can you draw from these observations about the role of the dnaA gene product? b. Explain your answers.
Expert Solution
steps

Step by step

Solved in 2 steps

Blurred answer
Knowledge Booster
Gene expression
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.
Similar questions
Recommended textbooks for you
Human Anatomy & Physiology (11th Edition)
Human Anatomy & Physiology (11th Edition)
Biology
ISBN:
9780134580999
Author:
Elaine N. Marieb, Katja N. Hoehn
Publisher:
PEARSON
Biology 2e
Biology 2e
Biology
ISBN:
9781947172517
Author:
Matthew Douglas, Jung Choi, Mary Ann Clark
Publisher:
OpenStax
Anatomy & Physiology
Anatomy & Physiology
Biology
ISBN:
9781259398629
Author:
McKinley, Michael P., O'loughlin, Valerie Dean, Bidle, Theresa Stouter
Publisher:
Mcgraw Hill Education,
Molecular Biology of the Cell (Sixth Edition)
Molecular Biology of the Cell (Sixth Edition)
Biology
ISBN:
9780815344322
Author:
Bruce Alberts, Alexander D. Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter Walter
Publisher:
W. W. Norton & Company
Laboratory Manual For Human Anatomy & Physiology
Laboratory Manual For Human Anatomy & Physiology
Biology
ISBN:
9781260159363
Author:
Martin, Terry R., Prentice-craver, Cynthia
Publisher:
McGraw-Hill Publishing Co.
Inquiry Into Life (16th Edition)
Inquiry Into Life (16th Edition)
Biology
ISBN:
9781260231700
Author:
Sylvia S. Mader, Michael Windelspecht
Publisher:
McGraw Hill Education