29 Questions
Which scientist published the double helical model of the DNA structure in 1953?
Watson & Crick
What is the main reason protein is considered rich in nitrogen?
High nitrogen content
What is the function of a nucleoside in DNA?
Carry genetic information
What was the organism used in the Hershey-Chase experiment to study DNA replication?
Phage T2
What did Erwin Chargaff's research reveal about DNA bases?
Variation among different species
What was the transforming material identified as in the 1944 experiment conducted by Oswald Avery, Colin MacLeod, and Maclyn McCarty?
DNA
Which analytical tool was used to determine the high molecular weight of the transforming material?
Ultracentrifugation
What characteristic of DNA helped differentiate it from proteins in the experiment?
Nitrogen/phosphorus ratio
Which wavelength of light absorption is most strongly associated with DNA?
260 nm
What did the average nitrogen/phosphorus ratio of 1.67 suggest about the transforming material?
It's DNA
Which analytical tool was used to match the absorption spectrum of the transforming material to that of DNA?
UV absorption spectrophotometry
Which technique did Maurice Wilkins and Rosalind Franklin use to analyze the three-dimensional structure of DNA?
X-ray diffraction
What does the arrangement of spots in an X-shape in X-ray diffraction analysis of DNA indicate?
Simple structure
Why is DNA considered simple when analyzed using X-ray diffraction?
Its large size implies a regular repeating structure
According to Crick and Watson, why are purines paired with pyrimidines in DNA?
To ensure uniform base pairs in double-stranded DNA
What is the significance of the spacing between adjacent spots in the X-ray diffraction pattern of DNA?
Correlates with overall helix length
How did Rosalind Franklin's X-ray results contribute to understanding DNA?
Gave information about DNA size and shape
Which of the following nitrogenous bases is found in DNA but not in RNA?
Thymine
What is the major structural difference between ribose and deoxyribose sugars?
Deoxyribose has an oxygen atom on the 2nd carbon atom while ribose doesn't.
Which of the following statements is true about nucleotides?
Thymidic acid is a pyrimidine nucleotide.
What structural feature gives nucleotide chains polarity?
Phosphate group location
Which scientist was known for discovering the Chargaff's rules for DNA base pairing?
Erwin Chargaff
What does Chargaff's rule regarding DNA structure state?
'A+T' equals 'G+C'
What is the correct number of hydrogen bonds between adenine and thymine in DNA?
2 hydrogen bonds
What type of bonding occurs between guanine and cytosine in DNA?
Hydrogen bonding
What is the distance between base pairs in the DNA molecule?
3.4 Å
How many base pairs are there approximately per turn of the DNA helix?
10 base pairs
What is the approximate diameter of the DNA molecule?
20 Å
In DNA, why must one strand have a 5'-3' polarity if the other has a 3'-5’ polarity?
To allow for complementary base pairing
Test your knowledge on the transformation process in bacteria and the discovery of DNA as the transforming material. Learn about Oswald Avery, Colin MacLeod, and Maclyn McCarty's experiment in 1944.
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