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Both the number of base pairs and the number of genes vary widely from one species to another, and there is little connection between the two (an observation known as the C-value paradox ). At present, the highest known number of genes is around 60,000, for the protozoan causing trichomoniasis (see List of sequenced eukaryotic genomes ), almost three times as many as in the human genome .

Note that a genome does not capture the genetic diversity or the genetic polymorphism of a species. For example, the human genome sequence in principle could be determined from just half the information on the DNA of one cell from one individual. To learn what variations in genetic information underlie particular traits or diseases requires comparisons across individuals. This point explains the common usage of "genome" (which parallels a common usage of "gene") to refer not to the information in any particular DNA sequence, but to a whole family of sequences that share a biological context.

Although this concept may seem counter intuitive, it is the same concept that says there is no particular shape that is the shape of a cheetah . Cheetahs vary, and so do the sequences of their genomes. Yet both the individual animals and their sequences share commonalities, so one can learn something about cheetahs and "cheetah-ness" from a single example of either.

Comparison of different genome sizes

Organism Genome size ( base pairs ) Note
Virus , Bacteriophage MS2 3,569 First sequenced RNA-genome [3]
Virus , SV40 5,224 [4]
Virus , Phage Φ-X174; 5,386 First sequenced DNA-genome [5]
Virus , Phage λ 48,502
Bacterium , Haemophilus influenzae 1,830,000 First genome of living organism, July 1995 [6]
Bacterium , Carsonella ruddii 160,000 Smallest non-viral genome. [7]
Bacterium , Buchnera aphidicola 600,000
Bacterium , Wigglesworthia glossinidia 700,000
Bacterium , Escherichia coli 4,600,000 [8]
Amoeba , Amoeba dubia 670,000,000,000 Largest known genome. [9]
Plant , Arabidopsis thaliana 157,000,000 First plant genome sequenced, Dec 2000. [10]
Plant , Genlisea margaretae 63,400,000 Smallest recorded flowering plant genome, 2006. [10]
Plant , Fritillaria assyrica 130,000,000,000
Plant , Populus trichocarpa 480,000,000 First tree genome, Sept 2006
moss , Physcomitrella patens 480,000,000 First genome of a bryophyte , January 2008 [11]
Yeast , Saccharomyces cerevisiae 12,100,000 [12]
Fungus , Aspergillus nidulans 30,000,000
Nematode , Caenorhabditis elegans 98,000,000 First multicellular animal genome, December 1998 [13]
Insect , Drosophila melanogaster aka Fruit Fly 130,000,000 [14]
Insect , Bombyx mori aka Silk Moth 530,000,000
Insect , Apis mellifera aka Honey Bee 1,770,000,000
Fish , Tetraodon nigroviridis , type of Puffer fish 385,000,000 Smallest vertebrate genome known
Mammal , Homo sapiens 3,200,000,000
Fish , Protopterus aethiopicus aka Marbled lungfish 130,000,000,000 Largest vertebrate genome known

Lecture 13. living organisms share common genes

All organisms store genetic information in the same molecules - DNA or RNA. Written in the genetic code of these molecules is compelling evidence of the shared ancestry of all living things. Evolution of higher life forms requires the development of new genes to support different body plans and types of nutrition. Even so, complex organisms retain many genes that govern core metabolic functions carried over from their primitive past.

Questions & Answers

I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
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Source:  OpenStax, Genetics. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10782/1.1
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