To analyse:
The structure of the molecule by postulating a model, which is consistent with the given observations.
Given:
The discovery of a primitive eukaryote with a unique
(a) X-ray diffraction studies show a general pattern resembling DNA (deoxyribonucleic acid), but has somewhat different dimensions and is more irregular.
(b) On heating and monitoring the UV (ultraviolet) absorption at 260 nm (nanometer), a major hypochromic shift is observed.
(c) Base-composition analysis shows four bases with proportions given below:
(1) Adenine is 8%
(2) Hypoxanthine is 18%
(3) Guanine is 37%
(4) Xanthine is 37%
(d) About 25 percent of the sugars are ribose and 75 percent are deoxyribose.
Introduction:
Watson and Crick proposed the double-stranded structure of DNA using X-ray diffraction. Four nitrogenous bases were discovered in DNA, out of which two were purines and two were pyrimidines. Purines are guanine and adenine while pyrimidines are thymine and cytosine in DNA. In RNA (ribonucleic acid), uracil is present instead of thymine. Hyperchromicity is the increase in the absorption of UV light by any
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Essentials of Genetics - Masteringgenetic
- Name and discuss using a representative example, the non-covalent interactions that maintains stability of the double helical structure of DNA.arrow_forwardGiven the structures of the nitrogenous bases below, draw the structure of a part of DNA with the sequence: 5'-GTTCA-3'.arrow_forwardA duplex DNA molecule contains a random sequence of the four nucleotides with equal proportions of each. What is the average spacing between consecutive occurrences of the sequence 5'-ATGC-3'? Between consecutive occurrences of the sequence 5'-TACGGC-3'?arrow_forward
- According to Chargaff's rule of nitrogenous base pairing, which of the following statements is correct? If all adenine bonds to thymine and all cytosine pairs with guanine, then the sum of all adenine will never be equal to the sum of all thymine in a DNA molecule. If all adenine bonds to thymine and all cytosine pairs with guanine, then the sum of all adenine will never be equal to the sum of all thymine in an RNA molecule. If all adenine bonds to thymine and all cytosine pairs with guanine, then the sum of all adenine equals the sum of all thymine in a DNA molecule. If all adenine bonds to uracil and all cytosine pairs with guanine, then the sum of all adenine will never be equal to the sum of all uracil in an RNA molecule.arrow_forwardHow do we know that the structure of DNA is in the form of a right-handed double-helical molecule?arrow_forwardWhen an aromatic hydrocarbon intercalates between two stacked base pairs, what effect may there be on DNA structure?arrow_forward
- Assuming the average weight of a deoxynucleotide monophosphate (dNMP) is 327.0 g/mol, how many picomoles of DNA are present in 500ng of a 1000bp DNA fragment?arrow_forwardWhich one of these facts would NOT be needed in order to determine the correct base sequence from the image of DNA in the question above? Adenine and guanine are purines with a two-ring chemical structure. Cytosine and thymine are pyrimidines with a one-ring chemical structure. Adenine pairs only with thymine using two hydrogen-bonds. Cytosine pairs only with guanine using three hydrogen-bonds. All of the facts above are needed.arrow_forwardTo create a DNA:RNA hybrid from a short stretch of DNA with the sequence 5'-GGCTAAGTATGCCTAGTAGC-3', design the corresponding RNA sequence. Indicate the sequence in a 5' to 3' manner. What type of helix (A, B or Z) will this double-stranded nucleic acid form?arrow_forward
- When Chargaff was performing his experiments, the tetranucleotide hypothesis, which stated that DNA was composed of GACT nucleotide repeats, was the most widely accepted view of DNA’s composition. How did Chargaff disprove this hypothesis?arrow_forwardHow many possible nucleotide sequences are there for a stretch of DNA that is N nucleotides long, if it is (a) single- stranded or (b) double-stranded?arrow_forwardWhich of the following (A through E ) would you expect to find in a nucleotide chain constructed for Sanger sequencing?arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning