a) Briefly describe three key differences between the genomes of prokaryotes and the genomes of multicellular eukaryotes. b) Chromosome inversions can have a major impact on evolutionary processes. Describe how chromosome inversions arise and the effect chromosome inversions have on the process of meiosis. What is the potential evolutionary significance of chromosome inversions? Solution a) Genomes of prokaryotes Genomes of eukaryotes Composed with single nacked, circular DNA. Composed with many linear DNA molecules, number varies from species to species. Chromosome organization is absent. Chromosome organization is present. Introns are absent. Introns are present. Centromeres, telomeres are absent Centromeres, telomeres are present. B) Chromosome inversion: Rearrangement of a chromosome segment. Inversion occurs when a single chromosome undergoes breakage and rearrangement within itself. These are two types includes pericentric inversions include a centromere, while paracentric inversions do not. Effect chromosome inversions have on the process of meiosis: A major or key evolutionary effect of inversions is that they suppress recombination in heterozygotes. This follows from the loss of unbalanced gametes that result from recombination. Large inversions show very low (but still positive) rates of recombination as heterozygotes, which results from double cross-overs and gene conversion, but the rates are orders of magnitude smaller than those in homozygotes. Evolutionary significance: Like other types of mutations, inversions evolve under selection and random drift. Many inversions, particularly small ones in intergenic regions, are likely to evolve neutrally (by drift alone). Selection can result in three ways. Inversions can generate structural problems with meiosis, as with some pericentric inversions. Alternatively, a breakpoint can disrupt an open reading frame or alter gene expression. The consequences can be deleterious, as in some human genetic diseases [6], but in other cases could cause an adaptive mutation. Finally, selection can act on an inversion when it carries one or more selected alleles. Genomes of prokaryotes Genomes of eukaryotes Composed with single nacked, circular DNA. Composed with many linear DNA molecules, number varies from species to species. Chromosome organization is absent. Chromosome organization is present. Introns are absent. Introns are present. Centromeres, telomeres are absent Centromeres, telomeres are present..

1. a) Briefly describe three key differences between the genomes of prokaryotes and the genomes
of multicellular eukaryotes.
b) Chromosome inversions can have a major impact on evolutionary processes. Describe how
chromosome inversions arise and the effect chromosome inversions have on the process of
meiosis. What is the potential evolutionary significance of chromosome inversions?
Solution
a)
Genomes of prokaryotes
Genomes of eukaryotes
Composed with single nacked, circular DNA.
Composed with many linear DNA molecules, number varies from species to species.
Chromosome organization is absent.
Chromosome organization is present.
Introns are absent.
Introns are present.
Centromeres, telomeres are absent
Centromeres, telomeres are present.
B) Chromosome inversion: Rearrangement of a chromosome segment. Inversion occurs when a
single chromosome undergoes breakage and rearrangement within itself.
These are two types includes pericentric inversions include a centromere, while paracentric
inversions do not.
Effect chromosome inversions have on the process of meiosis:
A major or key evolutionary effect of inversions is that they suppress recombination in
heterozygotes. This follows from the loss of unbalanced gametes that result from
recombination. Large inversions show very low (but still positive) rates of recombination as
heterozygotes, which results from double cross-overs and gene conversion, but the rates are
orders of magnitude smaller than those in homozygotes.
Evolutionary significance:
Like other types of mutations, inversions evolve under selection and random drift. Many
inversions, particularly small ones in intergenic regions, are likely to evolve neutrally (by drift
alone). Selection can result in three ways. Inversions can generate structural problems with
meiosis, as with some pericentric inversions. Alternatively, a breakpoint can disrupt an open
reading frame or alter gene expression. The consequences can be deleterious, as in some human

2. genetic diseases [6], but in other cases could cause an adaptive mutation. Finally, selection can
act on an inversion when it carries one or more selected alleles.
Genomes of prokaryotes
Genomes of eukaryotes
Composed with single nacked, circular DNA.
Composed with many linear DNA molecules, number varies from species to species.
Chromosome organization is absent.
Chromosome organization is present.
Introns are absent.
Introns are present.
Centromeres, telomeres are absent
Centromeres, telomeres are present.