GENOMES
TABLE OF CONTENTS
1. Introduction to Genomes
 Genomes of Eucaryotes
 Genomes of Procaryotes (Bacteria & Archeae)
2. Genome Projects
(MOST RECENT INFORMATION WILL BE ADDED WEEK 7 & 8)
1. Genomes of Eucaryotes:
 Genome sizes are very different if different in different eucaryotes. The size range
coincides to a certain extent with the complexity of the organism. Simple
eucaryotes (e.g. fungi) have smaller genomes and higher eucaryotes (e.g.
verterbrates & flowering plants) have larger genomes. (See table below).
Genome sizes of eucaryotes
Genome Size (Mb)
Organism
Fungi:
Saccharomyces cerevisiae
Aspergillus nidulans
12.1
25.4
Protozoa:
Tetrahymena pyriformis
190
Inverterbrates:
Caenorhabditis elegans (nematode worm)
Drosophila melanogaster (fruit fly)
Bombyx mori (silk worm)
Stronglyocentrotus purpuratus (sea urchin)
Locusta migratoria (locust)
100
140
490
845
5000
Verterbrates:
Fugu rubripes (pufferfish)
Homo sapiens (humans)
Mus musculus (mouse)
400
3000
3300
Plants:
Arabidiopsis thalania
Oryzae sativa (rice)
Pisum sativum (pea)
Zea mayis (maize)
Triticum aestivum (wheat)
Fritillaria assyricia (fritillary)
100
565
4800
5000
17000
120000

Human genomes is made of two distinct components:
 Nuclear genome contains 24 chromosomes (22 autosomes, and X & Y sex
chromosomes) totaling 3,000 Mb (3 million kb); the shortest is 55 Mb and
the longest 250 Mb.
 Mitochondrial genome is circular, totaling 16,569 bp. Note that plants
also have third genome located in the chloroplast.

Gene pool is not directly related to genome size. Human genome is 250 times the
size of the yeast genome and contains 80,000 genes. Accordingly, yeast genome
should only contain 320 genes but this is not the case as it contains 6,000 genes. It
is now recogonised that the genetic organisation of the yeast genome is much
more economical than the human genome: (a) The genes are much more compact
having fewer introns, (b) the spaces between the genes aka intergenic regions, are
much shorter and (c) the numbers of repeats and non-coding regions is much less.
It is remarkable that as the genome size increases so do the numbers of repeats.
You can observe this concept from comparing a 50 kb region from genomes of
human, yeast, maize and E.coli as shown below.
2. Genomes of Procaryotes