18 Questions
What is the backbone of the double-helix structure of DNA made of?
Sugar-phosphate
How are the two polynucleotide chains in DNA arranged with respect to polarity?
Antiparallel
What type of bonds pair the bases in the two strands of DNA?
Hydrogen bonds
Which of the following nucleotide base pairs with Thymine in DNA?
Adenine
In the double helix structure of DNA, what is the approximate distance between each base pair?
$0.34$ nm
How many base pairs are there approximately in each turn of the DNA double helix?
$10$ bp
What confers stability to the helical structure of DNA, in addition to H-bonds?
Distance between polynucleotide chains
Which scientist proposed the Central dogma in molecular biology, stating the flow of genetic information from DNA to RNA to Protein?
Francis Crick
What is the name of the reverse flow of genetic information in some viruses, from RNA to DNA?
Reverse transcription
How is the length of a DNA double helix typically calculated in a mammalian cell?
By multiplying the number of base pairs with the distance between them
What is the approximate length of a DNA double helix in a typical mammalian cell?
2.2 meters
In prokaryotes like E.coli, where is the DNA packaged despite the absence of a defined nucleus?
Throughout the cell
What did the Watson-Crick model suggest about the genetic material?
It would act as a template for synthesis of new strands.
Which term best describes the replication process proposed by the Watson-Crick model?
Semiconservative DNA replication
In the Meselson-Stahl experiment, what was used as the heavy isotope for nitrogen?
^15NH4Cl
How did Meselson and Stahl distinguish between heavy DNA and normal DNA in their experiment?
By centrifugation in a cesium chloride density gradient.
Which organism was first used to demonstrate semiconservative DNA replication according to the text?
Escherichia coli (E.coli)
What did the Meselson-Stahl experiment prove about DNA replication?
DNA replicates semiconservatively.
Test your knowledge on the salient features of the double-helix structure of DNA including its polynucleotide chains and sugar-phosphate backbone. Understand how the structure of DNA impacts its genetic implications.
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