GATE Genetics, Cell and Molecular Biology formula sheet

For two independent events, e.g. the genotype at one unlinked locus combined with the genotype at another unlinked locus.

For mutually exclusive outcomes, e.g. two different genotypes that give the same phenotype.

t₁ and t₂ are the times of entry (minutes after mixing) of two markers transferred by the same Hfr strain in the same direction. Distances from different Hfr strains are compared only after aligning each strain's order on the circular map.

C is a fraction (multiply by 100 for a percentage). Select for one donor marker, then score the unselected marker. Cotransformation frequency is defined the same way among transformants.

$p$ = frequency of allele $A$, $q$ = frequency of allele $a$ in the gene pool.

Valid whether or not the population is in Hardy-Weinberg equilibrium: each heterozygote carries one copy of each allele.

Here $N_0$ is the initial cell count, $N$ the count after time $t$, and $t_d$ the doubling time. It holds only while every cell is cycling with the same doubling time, with no cell death and outside any lag or stationary phase.

This follows directly from the exponential-growth formula under the same conditions.

For a simple 1:1 interaction. $K_d$ has units of concentration ($k_{off}$ in ${\text{s}}^{-1}$, $k_{on}$ in ${\text{M}}^{-1}{\text{s}}^{-1}$). A smaller $K_d$ means tighter (higher-affinity) binding. The association constant is $K_a=1/K_d$.

At $[L]=K_d$, $\theta =0.5$. Rearranged, $[L]=K_d\frac{\theta }{1-\theta }$, so moving from 10% to 90% occupancy needs an 81-fold rise in $[L]$ (from $K_d/9$ to $9K_d$). Valid only for one independent binding site per receptor.

$G$ = genome (or region) length in bp and $\ell$ = average Okazaki fragment length in nt. Every base pair is copied by exactly one fork, and each fork makes one strand continuously and the other discontinuously. So the total lagging-strand DNA equals $G$ nt, whatever the number of origins. Primer lengths and end effects at origins and termini are ignored.

4 bases in 3 positions give 64 codons: 61 sense codons (including AUG) and 3 stop codons (UAA, UAG, UGA).