Deoxyribonucleic Acid [ DNA] Flashcards
Who discovered the specific ratios of : nitrogenous bases in DNA in 1951?
Erwin Chargaff
What does Chargaff’s rule state about : the nitrogenous bases in DNA?
The amount of adenine is equal to thymine, and guanine is equal to cytosine.
What is the ratio of total purines to total pyrimidines in DNA according to Chargaff’s rule?
1:1
Who conducted X-ray diffraction analysis of DNA that contributed to the understanding of its structure?
Maurice Wilkins and Rosalind Franklin
What structure did Wilkins and Franklin claim DNA had?
A duplex (double helix) molecule
What is the width of the DNA duplex?
2nm
What is the length of each turn of the:
DNA duplex?
3.4nm
Who proposed the Watson and Crick model of DNA in 1953?
Francis Crick and James Watson
What does the Watson and Crick model state about the structure of DNA?
DNA is made up of two polynucleotide chains attached by base pairs.
How are the two polynucleotide chains’
in DNA oriented?
They are opposite in direction
+
(antiparallel).
What is the direction of one of the polynucleotide chains in DNA?
5’ to 3’ downward
What is the direction of the other polynucleotide chain in DNA?
5’ to 3’ upward
What is the width of both polynucleotide chains in DNA?
2nm
What is the specificity of base pairing: in DNA?
Adenine pairs with thymine, and guanine pairs with cytosine.
How many hydrogen bonds are between guanine and cytosine?
Three hydrogen bonds