Question

A hypothetical plant gene ADSH22 is encoded by the nuclear genome. The length of the mature mRNA for ADSH22 is 2150 nucleotides (nts). This mRNA has a 270 nts long 5' UTR and 200 nts long 3' UTR. Taking average molecular weight of an amino acid as 115 Dalton (Da), the calculated molecular weight of ADSH22 protein is ________ kDa (round off to 1 decimal place).

Hint:

To calculate the molecular weight of a protein, determine the number of amino acids, then multiply by the average molecular weight of an amino acid.

Answer 1

Correct Answer: 64.2

To calculate the molecular weight of the ADSH22 protein, we need to find the length of the coding region of the mRNA. The total length of the mRNA is 2150 nts, of which 270 nts are the 5' UTR and 200 nts are the 3' UTR. Thus, the length of the coding region is: \[ \text{Coding region length} = 2150 - 270 - 200 = 1680 \, \text{nts}. \] Each amino acid corresponds to approximately 3 nucleotides in the coding region. Therefore, the number of amino acids in the protein is: \[ \text{Number of amino acids} = \frac{1680}{3} = 560. \] The average molecular weight of an amino acid is 115 Da. Therefore, the molecular weight of the protein is: \[ \text{Molecular weight} = 560 \times 115 = 64400 \, \text{Da}. \] Since 1 kDa = 1000 Da, the molecular weight of the protein in kDa is: \[ \text{Molecular weight in kDa} = \frac{64400}{1000} = 64.4 \, \text{kDa}. \] Thus, the calculated molecular weight of ADSH22 protein is \( \boxed{64.2} \, \text{kDa} \).