Useful Conversion in Molecular Biology

PART I

 


Micrograms of Double-Stranded DNA to picomoles

How long is your DNA (in base pairs)?
How many micrograms of DNA do you have?
You have pmol of DNA
µg DNA x pmol x 106pg x 1 = pmol DNA
660pg 1µg N

N is the number of nucleotides and
660pg/pmol is the average molecular weight of a nucleotide pair

Picomoles of Double-Stranded DNA to micrograms and nanograms

How long is your DNA (in base pairs)?
How many pmol of DNA do you have?
You have
µg of DNA
ng of DNA
pmol DNA x 660pg x µg x N = µg DNA
pmol 106pg

or

pmol DNA x 660pg x ng x N = ng DNA
pmol 103pg

N is the number of nucleotides and
660pg/pmol is the average molecular weight of a nucleotide pair

Micrograms per milliliter of oligonucleotides (Single-Stranded DNA) to picomoles per microliter

How long is your oligo (in nucleotides)?
What is the concentration (in µg/ml)?
You have pmol/µl of DNA
µg DNA x ml x pmol x 106pg x 1 = pmol DNA
ml 1000µl 330pg 1µg N µl

N is the number of nucleotides and
330pg/pmol is the average molecular weight of a nucleotide

Picomoles per microliter of oligonucleotides (Single-Stranded DNA) to micrograms per milliliter

How long is your oligo (in nucleotides)?
What is the concentration (in pmol/µl)?
You have µg/ml of DNA
pmol DNA x 1000µl x 330pg x µg x N = µg DNA
µl ml pmol 106pg ml

N is the number of nucleotides and
330pg/pmol is the average molecular weight of a nucleotide

Micrograms of linear DNA to picomoles of ends

Amount of DNA (in µg)?
Size of DNA (in kb)?
You have pmol of ends
µg DNA x pmol x 106pg x 1 x 2 x kb = pmol DNA
660pg 1µg N 1000bp

N is the number of nucleotides (in kb),
660pg/pmol is the average molecular weight of a single nucleotide pair,
2 is the number of ends in a linear DNA molecule, and
kb/1000bp is a conversion factor from kilobases to base pairs

Molar ratio of insert to vector for ligations
(Generally ligations are tested at 1:3, 1:1, and 3:1 insert:vector molar ratios)

Length of insert (in kb)?
Amount of vector (in ng)?
Length of vector (in kb)?
. You need ng of insert for a 1:1 molar ratio
length of insert (in kb) x ng of vector = ng of insert needed for a 1:1 ratio
length of vector (in kb)

Conversion factors for metric prefixes

Prefix Factor
kilo 103
centi 10-2
milli 10-3
micro 10-6
nano 10-9
pico 10-12
femto 10-15
atto 10-18
zepto 10-21

Temperature Conversions

°F=°C = °K

°C = 5/9 (°F-32)

°F = 9/5 °C +32

°K = °C + 273.16

Oligonucleotide Melting Temperature Calculations

There are a number of different ways to calculate the melting temperature of an oligonucleotide. All of these methods will give different results. Please bear in mind that all of these calculations are theoretical! Exact melting temperatures must be determined empirically.

Enter your oligonucleotide sequence in the box below(Characters other than "G", "A", "T",and "C" will be ignored.)

OR select from the following Primers

What is the combined concentration of K+ and Na+ (in mM) in your reaction?
(note Promega's standard PCR buffers contain 50mM K+)
Promega's Access RT-PCR system was used.

The oligonucleotide is % GC The oligonucleotide is bases long
The molecular weight of the oligonucleotide is daltons.
The basic melting temperature is °C
The salt adjusted melting temperature of your sequence is °C
The melting temperature of your sequence using base stacking calculations is °C

LAST UPDATE

March 9, 2008

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