Conclusion From Genome Maps / Sequences -1. In general, there is conservation of linkage order among related species. For example, tomato and potato linkage maps differ with respect to five inversions involving complete chromosome arms.

A remarkable degree of conservation of linkage order has been observed in organisms as different as rice and maize. The conservation of linkage order in linkage maps of different species is known as synteny.

2. Eukaryotic genomes contain considerable extent (-5% of euchromatic DNA) of duplications of considerably large DNA segments.

5. In human genome, over 50% of the DNA consists of repeated sequences: 45% of the DNA is made-up of four classes of parasitic transposon, 3% is repeat of just a few bases, and about 5% is recent duplication of large segments of DNA.

6. The genome has G.C-rich and A.T-rich regions; the genes are more densely distributed in G.C-rich regions and their average intron size is smaller than those in the A.T-rich regions.

7. About 1,278 protein families are encoded by only -5% of the human genome. Of these, only 94 families are specific to vertebrates. The most elementary of cellular functions, e.g., basic metabolism, DNA replication, transcription and translation, have remained pretty well fixed since the evolution of bacteria and yeast.

8. Hundreds of human genes seem to have come directly by horizontal transfer from bacteria, rather than having evolved from bacterial genes. Further, dozens of genes appear to have been derived from transposons.

9. The pericentromeric and subtelomeric regions of chromosomes are filled with large recent segmental duplications of sequences from elsewhere in the genome.

10. The mutation rate is twice as high in male as in female meiosis.

11. Cytogenetic analysis of the sequenced clones confirms that large G.C-poor regions are strongly correlated with 'dark G-bands' in karyotypes.

12. Recombination rates tend to be much higher in distal regions of chromosomes and on shorter arms.

13. More than 104 million single nucleotide polymorph isms (SNPs) have been identified in the human genome.