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Approximately how long is a double-stranded DNA molecule with a molecular weight of 3x10^9 g/mol? Assume the molecular weight of one nucleotide is 333 g/mol, and that there are 10 base pairs for each turn of the DNA helix equalling 3.4nm in length.

Let's begin by assessing the molecule. If we divide the molecular weight by two, that will give us the weight for one strand of the helix. Knowing that one nucleotide is 333 g/mol, then dividing the weight o...
AV
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If a solution, contained in a 1cm cuvette, has an absorbance value of of 0.865 A.U, and concentration value of 2mM. What is the value regarding the molar extinction coeffient?

Firstly, using Beer-Lambert's equation. It is noted, that absorption is equal to the molar extinction coefficient, multiplied by the path length of light, multiplied by the concentration of the solution.Ther...
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Answered by Aaron V. • Chemistry tutor
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Why does tanx = sinx/cosx ?

This identity can easily be shown by asking the student to draw a right-angled triangle, with one of the remaing two angles labelled x, and labelling the respective oppposite, adjacent and hypotenuse sides O...
SR
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How do I improve my QR score?

The greatest problem with the quantitative reasoning section is without a doubt the time pressure. One of the ways to tackle this is to be able to quickly ascertain which questions will take too much of your...
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Answered by Dan V. • UCAT tutor
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How do I know when to use avoir and when to use être in the passé composé - the perfect tense?

The passé composé - the perfect tense - is used for talking about completed events in the past, such as 'I bought an apple', and it is formed using an auxiliary verb the present tense and a past participle. ...
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Answered by Isobel M. • French tutor
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