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DNA质量-摩尔量转换
Accurately measuring the quantity of your DNA is imperative for a range of
molecular biology applications, including
vector cloning, PCR, and transfection. VectorBuilder’s DNA calculator allows you to
easily retrieve molecular weight and amount of your DNA (mass or moles) to
ensure correct setup of your experiment. (Note: Nucleic acid molecular weight
calculations assume deprotonated phosphate hydroxyl groups.)
Molecular weight calculation
Knowing the molecular weight of your compound is important for biology applications ranging from simple molecular biology processes like gel electrophoresis to clinical drug development. Molecular weight is determined by summing the weights of the protons, neutrons, and electrons in a molecule. To convert between mass and moles of a biomolecule, the molecular weight of a biomolecule must first be obtained. To determine the molecular weight of a stretch of DNA, sum the molecular weights of each nucleotide in the DNA sequence. Example calculations are shown below for the DNA base deoxy-adenosine. Alternatively, if just the sequence length is entered, the average nucleotide molecular weight is multiplied by the length for an approximation.
Figure 1. Chemical structure of deoxy-adenosine and example calculation of molecular weight.
Mass - moles converter
In chemistry, a mole represents a quantity of substance containing Avogadro's number of particles (6.02214076 × 1023), typically atoms or molecules. After obtaining the molecular weight of a biomolecule by summing the molecular weights of its components, the mass and moles of a substance can be calculated using the following equation:
Moles DNA (mol) = Mass DNA (g) / Molecular Weight (g/mol)
Figure 2. Equation used to convert between moles and mass of a substance with known molecular weight.
Copy number determination
To calculate the copy number of DNA from the number of moles, multiply the number of moles by Avogadro’s number (6.02214076 × 1023). This calculation is the same for single-stranded and double-stranded molecules as the calculation is based on the number of molecules, not the individual nucleotides.
Copy Number (copies of molecules) = Moles DNA (mol) x 6.022 x 1023
molecules/mol
Figure 3. Equation to determine the copy number for single- and double-stranded DNA.
Moles 3'/5' ends calculation
To calculate the moles of 3' and 5' ends of DNA, it is important to distinguish between single-stranded (ssDNA) and double-stranded DNA (dsDNA). In ssDNA, each molecule has one 3' end and one 5' end, so the moles of 3' ends and 5' ends are equal to the moles of ssDNA present. In contrast, dsDNA consists of two complementary strands, each with a 3' and a 5' end. Therefore, the following equations can be used to determine the moles of 3'/5' ends given that the state of the DNA molecule is known.
Moles 3'/5' Ends (mol) = Moles ssDNA (mol)
Moles 3'/5' Ends (mol) = Moles dsDNA (mol) x 2
Figure 4. Equations to determine the moles of 3'/5' ends for single- and double-stranded DNA.
