To analyze:
The ratio of purine to pyrimidine for the given set of deoxyribonucleic acid (DNA), observation of a pattern, and the relation of this pattern to the DNA structure.
Given:
The composition of DNA is different in different organisms. The composition of DNA bases in some organisms is tabulated as follows in Table 1:
Table 1: The composition of DNA bases in some organisms
Organism and the tissue from which DNA is extracted | The composition of DNA base (%) | |||
Adenine | Guanine | Cytosine | Thymine | |
Herring sperm | 27.8 | 22.2 | 22.6 | 27.5 |
Rat bone marrow | 28.6 | 21.4 | 21.5 | 28.4 |
Human sperm | 30.7 | 19.3 | 18.8 | 31.2 |
Escherichia coli | 26.0 | 24.9 | 25.2 | 23.9 |
Yeast | 31.3 | 18.7 | 17.1 | 32.9 |
Introduction:
Purines are the heterocyclic compounds, which contain carbon, hydrogen, and nitrogen atoms. They contain a double ring system. Pyrimidine is also heterocyclic compounds, but they contain a single ring. The concentration of both purines and pyrimidine are important to define the genetic code of an individual. The DNA consist of two types of purines, that are, guanine (G) and adenine (A) (remember ‘i’ in purine, adenine, and guanine), and two types of pyrimidine, that are, thymine (T) and cytosine (C) (remember ‘y’ in cytosine, thymine, and pyrimidine).
Explanation of Solution
Each purine is bonded to a pyrimidine with the help of hydrogen bonds. The adenine is bonded to thymine by two hydrogen bonds and cytosine is bonded to guanine by three hydrogen bonds. The rule of bonding of a pyrimidine with a purine is called as the Chargaff’s rule. The number of purines is always equal to the number of pyrimidines.
The ratio of purine to pyrimidine is calculated by dividing the total amount of purine with the total amount of pyrimidines and it can be seen in Table 2 given below:
Table 2: Ratio of purine to pyrimidine
Organism and the tissue from which DNA is extracted | Purines | Pyrimidines | Ratio | ||
A+G | C+T | ||||
Herring sperm pyrimidines ratio | |||||
Rat bone marrow | |||||
Human sperm | |||||
Escherichia coli | |||||
Yeast |
From Table 2, it is clear that the ratio of purine to pyrimidine is always equal to 1. This means that the DNA always occurs as a double helix structure in which one purine is always bonded to one pyrimidine.
Thus, it can be calculated from Tables 1 and 2 that each organism has a different composition of DNA bases but the ratio of purines to pyrimidine is always equal to 1 indicating that DNA is a double helix structure, in which each purine is hydrogen bonded to a pyrimidine.
Want to see more full solutions like this?
Chapter 4 Solutions
Life: The Science of Biology
- Which two species in this DNA sequence alignment are the most closely related? Explain your answer referring to specific nucleotide positions to justify the choice you made.arrow_forwardDraw the following structures and rate their relative solubilities in water (most soluble to least soluble): deoxyribose, guanine, phosphate. How are these solubilities consistent with the three-dimensional structure of double-stranded DNA?arrow_forward. In analyzing the number of different bases in a DNAsample, which result would be consistent with thebase-pairing rules?(A) A = G(B) A + G = C + T(C) A + T = G + C(D) A = Carrow_forward
- Considering the number of base pairs, compute for the actual length (in micrometers) of this DNA modelarrow_forwardIn isolating DNA in strawberries, can you isolate other biomolecules aside from DNA just by using commonly available household materials and chemicals? Elaborate on your answer.arrow_forwardA student has drawn an enlarged portion of a DNA “ladder” model to show two of the nucleotides in greater detail (in the same orientation as they would occur in the ladder model). Which two nucleotides did the student draw?arrow_forward
- What are the features that make the structure of the DNA stable? Explain why the DNA is the genetic material.arrow_forwardUse a drawing to illustrate the principle of DNA gel electrophoresis. Indicate roughly the comparative electrophoretic mobilities of DNAs with 150, 600, and 1200 bp.arrow_forwardIn each case, if 1 µg of DNA was digested by these enzymes, calculate the number of ng of DNA present in each fragment (complete the table).arrow_forward
- How 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_forwardRefer to the attached DNA model. In the spaces provided on the attached table, identify the nitrogenous bases for the first 5 base pairs from the top, and for the 5 base pairs from the bottom of the model. Use ‘A’, ‘G’, ‘C’, ‘T’ to indicate the proper base. Polarity does matter.arrow_forwardWith regard to Chargaff’s experiment described in Figure shown,answer the following:A. What is the purpose of paper chromatography?B. Explain why it is necessary to remove the bases in order todetermine the base composition of DNA.C. Would Chargaff’s experiments have been convincing if theyhad been done on DNA from only one species? Discuss.arrow_forward
- Human Anatomy & Physiology (11th Edition)BiologyISBN:9780134580999Author:Elaine N. Marieb, Katja N. HoehnPublisher:PEARSONBiology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStaxAnatomy & PhysiologyBiologyISBN:9781259398629Author:McKinley, Michael P., O'loughlin, Valerie Dean, Bidle, Theresa StouterPublisher:Mcgraw Hill Education,
- Molecular Biology of the Cell (Sixth Edition)BiologyISBN:9780815344322Author:Bruce Alberts, Alexander D. Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter WalterPublisher:W. W. Norton & CompanyLaboratory Manual For Human Anatomy & PhysiologyBiologyISBN:9781260159363Author:Martin, Terry R., Prentice-craver, CynthiaPublisher:McGraw-Hill Publishing Co.Inquiry Into Life (16th Edition)BiologyISBN:9781260231700Author:Sylvia S. Mader, Michael WindelspechtPublisher:McGraw Hill Education