First Stage: Separation
Speciation usually begins when a part of a population becomes separated from the rest of their species.
Second Stage: Adaptation
Adaptation in speciation is quite similar, though the groups may evolve different sets of traits if the environmental conditions differ for each group.
Third Stage: Reproductive Isolation
Reproductive isolation is when groups of a same species are reunited and cannot interbreed with each other anymore, so they are now identified as different species.
Cell differentiation is the process by which cells specialize to achieve their required functions. In order for a cell to differentiate, it will express specific genes. ... Importantly, mitosis produces cells that are identical to each other (clones).
I think the apparent weakness that exists in applying this model of nucleic acid structures are; If it was single tetramer of 4 then it would not be able to have the complexity of the linear sequence, and also it could account for significant quantity if there were enough individual tetramers.
DNA molecule is a made up of nucleotides bases, that are linked together in long chains. Each nucleotide is made up of a sugar (deoxyribose sugar), a nitrogenous base, and a phosphate group. The nucleotides bases on one strand of the DNA pairs with the nucleotide on the other strand (adenine pairs with Thyamine and guanine with Cytosine). The secondary structure of the polymer is responsible for the shape that the nucleic acid assumes.
