Chapter 1Evolution of the Cell
2 Variation in nucleic acids provided the variation in organisms upon which
natural selection could act.
5 The increase in size of eukaryotic cells was possible because of the
development of intracellular compartments and transport systems.
Each gene contains many separate exons separated by large introns, so that only a small proportion of the region shown (< 5%) actually encodes protein.
The region between the two genes contains several regulatory elements (not individually identified), which control whether the gene will be transcribed or not.