# GATE2020: 44

$E$ coli was grown in $^{15}N$ medium for several generations. Cells were then transferred to $^{14}N$ medium, allowed to grow for $4$ generations and $DNA$ was isolated immediately. The proportion of total $DNA$ with intermediate density is ___________ (round off to $2$ decimal places).
in Others
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## Related questions

1
The number of molecules of a nucleotide of molecular weight $300\:g$/mol present in $10$ picomoles is ____________ $\times10^{12}$ (round off to $2$ decimal places).
2
To facilitate mass transfer from a gas to a liquid phase, a gas bubble of radius $r$ is introduced into the liquid. The gas bubble then breaks into $8$ bubbles of equal radius. Upon this change, the ratio of the interfacial surface area to the gas phase volume for the system changes from $3/r$ to $3n/r$. The value of $n$ is _____________________.
A variable $Y$ is a function of $t$. Given that $Y\left ( t=0 \right )=1$ and $Y\left ( t=1 \right )=2,\dfrac{dY}{dt}$ in the interval $t=\left [ 0,1 \right ]$ can be approximated as _________________.
The sequence of a $1$ $Mb$ long $DNA$ is random. This $DNA$ has all four bases occurring in equal proportion. The number of nucleotides, on average, between two successive $EcoRI$ recognition site $GAATTC$ is ____________.
A batch reactor is inoculated with $1 \:g/L$ biomass. Under these conditions, cells exhibit a lag phase of $30$ min. If the specific growth rate in the log phase is $0.00417\;min^{-1}$, the time taken for the biomass to increase to $8 \:g/L$ is ________________ min (round off to $2$ decimal places).