Stockholm Bioinformatics Center, SBC
Lecture notes: Structural biochemistry and bioinformatics 2001
Lecture 23 Nov 2001,
5. Comparing genomes
One of the most interesting new fields that the availability of the
complete genomes has created is the science of genome
comparison. Comparing complete genomes can give deep insights about
the relationship between organisms, as well as shedding light on the
function of specific genes in each single genome. It is clear that
this field has just begun, and that there are many discoveries waiting
to be made.
Some examples of issues that have been investigated to some degree:
It is now possible to investigate which sets of genes are common to
many different organisms, or groups of organisms. Is there a common
core of genes necessary for all life? Is that core sufficient for
Are all the ribosomal proteins really similar between all known
species, or have there been inventions during the course of evolution
in this specific, but fundamental system?
Which genes are necessary for multicellular life forms; which set of
genes are only found in multicellular organisms but not in unicellular
The rate of horizontal gene transfer (genes that have jumped the
species barrier) among bacteria can now be investigated. How often,
and under what circumstances do bacteria exchange genes? Has anything
similar happened with higher organisms?
Where and how have new genes emerged in evolutionary history? Can
precursors of some gene families be found in distant relatives of a
The problem of identifying and characterizing orthologous genes versus
paralogous genes becomes easier to address (but not necessarily
Warning: The term orthologous and paralogous are
sometimes used to denote functional equivalence, and similarity
without functional equivalence, respectively, but this is frowned upon
by evolutionary biologists.
- Orthologues are genes that have diverged from a common
ancestor because of a speciation event.
- Paralogues are genes that have diverged as the result of
a gene duplication event.
Copyright © 2001
$Date: 2001/11/19 13:49:36 $