The DNA alpha-helix structure has 566900 complete turns. The average molar mass of one base pair of nucleotides in DNA is approximately 469 g/mol. If the spacing between successive base pairs is about 0.69 nm, and a complete turn in the helical structure of DNA occurs every 6.9 nm, calculate molar mass of DNA molecule. [Answer: 2.66 x 10^9 g/mol]
I just need the steps on how to solve problems like this. Please help and thanks in advance.
Yuh
To solve this problem, follow these steps:
Step 1: Find the number of base pairs in one complete turn of the DNA alpha-helix:
Since the spacing between successive base pairs is about 0.69 nm, and a complete turn in the helical structure of DNA occurs every 6.9 nm, divide the spacing of a complete turn (6.9 nm) by the spacing between successive base pairs (0.69 nm) to find the number of base pairs in one complete turn:
Number of base pairs in one complete turn = 6.9 nm / 0.69 nm = 10 base pairs
Step 2: Calculate the number of complete turns in the DNA alpha-helix:
Given that the DNA alpha-helix structure has 566900 complete turns, we can skip this step.
Step 3: Find the total number of base pairs in the DNA alpha-helix:
Multiply the number of base pairs in one complete turn by the number of complete turns:
Total number of base pairs = Number of base pairs in one complete turn x Number of complete turns
Total number of base pairs = 10 base pairs/turn x 566900 turns = 5,669,000 base pairs
Step 4: Calculate the molar mass of the DNA molecule:
The average molar mass of one base pair of nucleotides in DNA is approximately 469 g/mol. To find the molar mass of the DNA molecule, multiply the number of base pairs by the molar mass of one base pair:
Molar mass of DNA molecule = Total number of base pairs x Average molar mass of one base pair
Molar mass of DNA molecule = 5,669,000 base pairs x 469 g/mol = 2.66 x 10^9 g/mol
Therefore, the molar mass of the DNA molecule is approximately 2.66 x 10^9 g/mol.