When gene frequencies stay relatively constant, Hardy-Weinberg equilibrium occurs. HW equilibrium occurs in large populations with random mating, with no migration, mutation, or natural selection. In this case, the proportion of dominant homozygous equals the square of the frequency of the dominant allele (p2), the proportion of recessive homozygous equals the square of the frequency of the recessive allele (q2<span>) and the proportion of heterozygotes equals 2pq.</span>
Synapse pruning is the process when the synapses are eliminated and it occurs usually in the early childhood. Synapses that are eliminated are the ones that organism no longer needs. Synaptic pruning process is regulated and influenced by environmental factors.
