Stockholm Bioinformatics Center, SBC
Lecture notes: Molecular Bioinformatics 2001,
Lecture 26 Jan 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 life?
If one looks at a specific, and yet fundamental, component such as the
ribosome and the protein synthesis, can one say anything about whether
this system has changed fundamentally through evolution, or has it
stayed basically the same throughout? Have there been
inventions during evolution in such a fundamental
Which genes are necessary for multicellular life
forms; which set of genes are only found in multicellular organisms
but not in unicellular ones?
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 species?
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: 2001/01/24 10:18:58 $