If Adenine makes 30% of the DNA molecule, what will be the percentage of Thymine, Guanine and Cytosine in it ?
T : 20 ; G : 25 ; C : 25
T : 20 ; G : 30 ; C : 20
T : 20 ; G : 20 ; C : 30
T : 30 ; G : 20 ; C : 20
The Correct Option is D
Solution and Explanation
To solve the question of determining the percentages of Thymine, Guanine, and Cytosine in a DNA molecule where Adenine makes up 30%, we should understand the structure of DNA.
DNA is composed of four types of nitrogenous bases: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C). The amount of Adenine is always equal to the amount of Thymine, and the amount of Guanine is always equal to the amount of Cytosine. This is known as Chargaff's rule.
- Since Adenine (A) makes up 30% of the DNA, by Chargaff's rule, Thymine (T), which pairs with Adenine, must also make up 30%.
- Since the total percentage of all the bases in DNA must equal 100%, the combined percentage of Guanine (G) and Cytosine (C) must account for the remaining percentage. Therefore, G + C = 100% - (A + T).
- Substituting the known values: G + C = 100% - (30% + 30%) = 40%.
- Because Guanine and Cytosine are equal, we have G = C. Therefore, G + C = 2G = 40%.
- Solving for G: 2G = 40% implies G = 20%. Therefore, C = 20%.
Thus, the percentages of Thymine, Guanine, and Cytosine in the DNA molecule are:
- Thymine (T): 30%
- Guanine (G): 20%
- Cytosine (C): 20%
Therefore, the correct answer is: T : 30 ; G : 20 ; C : 20.
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Concepts Used:
Discovery of DNA
DNA - Discovery
Many individuals believe that American biologist - "James Watson" and English physicist - “Francis Crick” discovered DNA in the 1950s. Actually, this is not the case. Preferably, DNA was first recognized in the late 1860s by Swiss chemist - “Friedrich Miescher”.
Read More: Structure of DNA
What actually DNA is?
DNA is self-replicating material that exists in every living organism. In easiest terms, it is a carrier of all genetic information. It contains the instructions required for organisms to develop, grow, survive, and reproduce. It’s one of the longest molecules that contain our genetic “code,” or recipe. This recipe is the initial point for our development, but DNA’s interaction with outside impacts such as our lifestyle, environment, and nutrition ultimately forms human beings.
DNA is a composition of molecules known as nucleotides. Each nucleotide comprises a sugar and phosphate group, also nitrogen bases. These nitrogen bases are further tumbledown into four types, including:
- Adenine (A)
- Cytosine (C)
- Guanine (G)
- Thymine (T)