Question

Molecular weight of the genomic DNA of an organism is 3.96 x 10⁹ g/mol. The average molecular weight of nucleotide pair is 660 g/mol. If an average protein in this organism consists of a chain of 400 amino acids, the maximum number of proteins coded by DNA molecule will be ..............

Hint:

To find the number of proteins coded by a DNA molecule, divide the total number of codons by the number of codons required for each protein.

Answer 1

Correct Answer: 4995

Step 1: Calculate the total number of nucleotide pairs in the DNA.
The molecular weight of the DNA is 3.96 x 10⁹ g/mol, and the molecular weight of one nucleotide pair is 660 g/mol. The total number of nucleotide pairs is: \[ \text{Number of nucleotide pairs} = \frac{\text{Molecular weight of DNA}}{\text{Molecular weight of one nucleotide pair}} = \frac{3.96 \times 10^9}{660} = 6.0 \times 10^6. \]

Step 2: Calculate the number of codons in the DNA.
Since each codon consists of 3 nucleotide pairs, the number of codons is: \[ \text{Number of codons} = \frac{6.0 \times 10^6}{3} = 2.0 \times 10^6. \]

Step 3: Calculate the maximum number of proteins coded by the DNA.
Each protein consists of 400 amino acids, and each codon codes for one amino acid, so the maximum number of proteins coded by the DNA is: \[ \text{Maximum number of proteins} = \frac{2.0 \times 10^6}{400} = 3.0 \times 10^6. \]

Step 4: Conclusion.
The maximum number of proteins coded by the DNA molecule is 3.0 x 10⁶.