Concept explainers
(a)
To describe: The two structural features required by a DNA molecule to maintain a negatively supercoiled state.
Introduction:
Supercoiling is important for packaging of circular DNA molecule referred as closed circular double helix DNA. DNA can be supercoiled in two ways, positive supercoiling and negative supercoiling. Positive supercoiling is the right-handed and double helical form of DNA, while negative supercoiling is the left-handed and double helical form of DNA.
(b)
To enlist: Three structural changes that become more favorable when a DNA molecule is negatively supercoiled.
Introduction:
Deoxyribonucleic acid (DNA) is a genetic material which is responsible for passing information from one generation to another. It is a double helical structure which consists of “two parallel strands” made up of
(c)
To determine: The enzyme that can generate negative superhelicity in DNA with the aid of ATP.
Introduction:
Topoisomerase II or DNA gyrase “reduces supercoiling” in the
(d)
To describe: The physical mechanism by which this enzyme acts.
Introduction:
In replication and transcription, DNA gyrase causes relaxing of positive supercoils and possess the ability to add negative supercoils within the DNA.

Want to see the full answer?
Check out a sample textbook solution
Chapter 24 Solutions
Lehninger Principles of Biochemistry (Instructor's)
- Show the fate of the proton on the 4-Oxygen molecule of F-1,6-BP. Please include a drawing showing the electron flow that occurs.arrow_forward1. Which one is the major organic product obtained from the following aldol condensation? O NaOH, H₂O heat A B C D Earrow_forwardAn organic chemist ordered the wrong item. She wanted to obtain 1-hydroxy-2-butanone, butinstead ordered 2-hydroxybutyraldehyde. As a good biochemist, show how the organic chemistcould use biological catalysis to make her desired compound. Please show the mechanism by drawing.arrow_forward
- Show the fate of the hydrogen on carbon-2 of glucose. Please draw out the structure using curve arrows to show electron flow.arrow_forward3. Which one of the compounds below is the major product formed by the reaction sequence shown here? CH3 + CH3NO2 NaOH H2, Ni ? nitromethane acetophenone OH OH HO HN- u x x x x Ph A HO -NH2 HO H Ph Ph Ph N- H B Ph NH2 D Earrow_forward4. Only ONE of the five compounds below can be prepared by an aldol condensation in which a single carbonyl compound is treated with base. Which one is it? To solve this problem, reverse the aldol condensation that formed each of these molecules to find out what two molecules came together to make the products. The one in which the two molecules are identical is the answer. Ph Ph ཚིག གནས ག ནཱ ཀ ན ཀནཱ A Ph H B Ph Ph H D Ph. Ph Ph E Harrow_forward
- 5. Which one is the major organic product obtained from the following reaction sequence? First, equimolar amounts of cyclopentanone and LDA are mixed at -78°C. Then propionaldehyde (propanal) is added. Addition of aqueous acid completes the process. LDA, -78°C. 1. 2. H₂O* H A B H 0 D H H Earrow_forward2. Which one is the major organic product obtained from the following reaction? NaOH, H₂O heat A B C D Earrow_forwardCH3CH2CHO + propanal PhCH2CHO 2-phenylacetaldehyde mixture of four products NaOH 10. In the crossed aldol reaction of propanal and 2-phenylacetaldehyde shown above, a mixture of four products will be formed. Which ONE of the compounds below will NOT be formed in this crossed aldol reaction? OH Ph A H OH OH Ph H B OH OH H H H Ph Ph C Ph D Earrow_forward
- An organic chemist ordered the wrong item. She wanted to obtain 1-hydroxy-2-butanone, butinstead ordered 2-hydroxybutyraldehyde. As a good biochemist, show how the organic chemistcould use biological catalysis to make her desired compound.arrow_forwardPredict the products of aldolase catalyzing the reaction with acetone and (S)-3-hydroxybutyraldehyde.arrow_forwardA cancer patient undergoing chemotherapy is taking a protein kinase inhibitor drug. The patientis an avid marathon runner and does not want to miss his upcoming race. Is it a good idea forthis patient to attempt a marathon while on this medication? Explain why or why not.arrow_forward
- BiochemistryBiochemistryISBN:9781319114671Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.Publisher:W. H. FreemanLehninger Principles of BiochemistryBiochemistryISBN:9781464126116Author:David L. Nelson, Michael M. CoxPublisher:W. H. FreemanFundamentals of Biochemistry: Life at the Molecul...BiochemistryISBN:9781118918401Author:Donald Voet, Judith G. Voet, Charlotte W. PrattPublisher:WILEY
- BiochemistryBiochemistryISBN:9781305961135Author:Mary K. Campbell, Shawn O. Farrell, Owen M. McDougalPublisher:Cengage LearningBiochemistryBiochemistryISBN:9781305577206Author:Reginald H. Garrett, Charles M. GrishamPublisher:Cengage LearningFundamentals of General, Organic, and Biological ...BiochemistryISBN:9780134015187Author:John E. McMurry, David S. Ballantine, Carl A. Hoeger, Virginia E. PetersonPublisher:PEARSON





