DNA molecule having the length of 68Å, contains 10\% Adenine. How many number of hydrogen bonds are present between nitrogen bases totally in that DNA?
In a DNA molecule, hydrogen bonds are formed between nitrogenous bases as follows:
- Adenine (A) forms two hydrogen bonds with Thymine (T).
- Guanine (G) forms three hydrogen bonds with Cytosine (C). Given that the DNA contains 10\% Adenine, and accordingly 10\% Thymine due to base-pairing rules, 20\% of the bases are A and T. The remaining 80\% are equally divided between Guanine and Cytosine. Calculating the total number of base pairs: \[ \text{Total base pairs} = \frac{68 \text{ Å}}{3.4 \text{ Å/base pair}} = 20 \text{ base pairs}. \]
Hydrogen bonds calculations: - Number of A-T pairs: \( 10\% \times 20 \text{ base pairs} = 2 \text{ A-T pairs} \). - Hydrogen bonds from A-T pairs: \( 2 \text{ pairs} \times 2 \text{ bonds} = 4 \text{ bonds} \). - Number of G-C pairs: \( 40\% \times 20 \text{ base pairs} = 8 \text{ G-C pairs} \). - Hydrogen bonds from G-C pairs: \( 8 \text{ pairs} \times 3 \text{ bonds} = 24 \text{ bonds} \).
Total hydrogen bonds: \( 4 + 24 = 28 \times 2 = 56 \). This reflects that each pair (A-T and G-C) accounts for two strands, hence the hydrogen bonds calculated per pair are doubled for the entire double helix structure, providing a total of 56 hydrogen bonds, aligning with option (2).
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Assertion (A): Endosperm is haploid in Gymnosperms
Reason (R): Female gametophytic tissue acts as endosperm in Gymnosperms
In the following group of plants, sporophytes are dependent on gametophytes.
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