G.H. Hardy and W. Weinberg together proposed the Hardy-Weinberg principle, which states that if a population is not undergoing any kind of evolutionary change, it is said to be in genetic equilibrium. The term “genetic equilibrium” means that the frequency of occurrence of alleles of a gene remains fixed and same throughout generation to generation. It implies that allele frequencies in a population are stable and the gene pool (total genes and their alleles) of a population remains constant. This principle also states that the sum total of all the allelic frequencies of a gene is 1.
Hardy and Weinberg used an algebraic equation to explain this:
P2 + 2pq + q2 = 1
Where, p = frequency of the dominant allele
q = frequency of the recessive allele
pq = frequency of heterozygotes
This equation is a binomial expansion of (p + q)2.
Five factors affect the Hardy-Weinberg equilibrium:
Any change in frequency of alleles in a population results in evolution.
In prokaryotes, DNA is not scattered throughout the cell although they do not have a defined nucleus. DNA is found lying centrally in the cytoplasm in a condensed form. The coiled DNA is maintained in place by non-histone basic proteins having positive charge. DNA being negatively charged is held by these basic polyamines and this region is termed as nucleoid or genophore. The DNA is packed in large loops in the nucleoid.
A PROKARYOTIC CELL SHOWING NUCLEOID
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