A simple working definition that is widely used is " All the information that is encoded in DNA or RNA and is capable of being passed on to an offspring"

So for example, in humans, the genome is all of the nuclear DNA in a haploid cell (sperm or egg) i.e., DNA that is inherited by the next generation. So a normal somatic cell in humans actually has two genomes, a maternal genome and a paternal genome

I suggest to read the article entitled "What is a genome?" by Stencel and Crespi, published in Molecular Ecology (2013) 22, 3437–3443.

As a concept the singular genome per species or organism is useful, but I think one aspect is often missed within this definition. We know that different individuals within species such as humans do not actually share a single genome, so the human genome project produced a reference genome representative of the species but not necessarily any single individual.

Why not also consider the notion of multiple genomes per individual (variable genetic material among different cells within a single multi-cellular organism such as a human)? The genomes of some types of cells such as erythrocytes or megakaryocytes are radically altered by removal or amplification of nuclear material, respectively, during maturation. B cells and T cells can be clonal (generating unique genomes) after undergoing somatic hypermutation. Also, as mutations inevitably accumulate in essentially all cells (both somatic and germ cells) throughout an organism's lifespan, the organism becomes a composite of many genomes. This actually has implications for treatment for diseases such as cancer.

See Terrence Wong's excellent talk at ASH 2013 showing pre-existing p53 mutations in rare cells being selected upon in therapy-related AML.

http://web.oncoletter.ch/files/cto_layout/Kongressdateien/ASH2013%20Oral%20Sessions/ASH13Plen5Wong.pdf

Totality of the genes present in an organism is the genome.

I am with Arun Jugran... The whole sum of DNA or RNA Which is Present in Cell is Genome whether it is coding or non-coding.

Read this article. I think you might find it useful. Link below

Stencel and Crespi. what is a genome? Molecular Ecology (2013) 22, 3437–3443

http://onlinelibrary.wiley.com/doi/10.1111/mec.12355/pdf

Dear Dacguin,

may be you have overlooked, but I have already suggested to read this article a day ago. Please read all the previous answers, before you add yours!

Indeed, I did not see your early answer; it is not a issue though

Andrei, we are talking about the genome, not the genes - it seems to be quite different items!

The genome is the complete set of genes in an organism. In other words, the total amount of genetic information in the chromosomes of an organism, including its genes and DNA sequences. The genome of eukaryotes is made up of a single, haploid set of chromosomes that is contained in the nucleus of every cell and exists in two copies in the chromosomes of all cells except reproductive and red blood cells. The human genome is made up of about 25,000-35,000 genes.

An organism's genome is made up of molecules of deoxyribonucleic acid (DNA) that form long strands that are tightly wound into chromosomes, which are found in the nucleus of eukaryotic organisms and in the cytoplasm of prokaryotic organisms. Chromosomes that are unique to certain organelles within a cell, such as mitochondria or chloroplasts, are also considered a part of an organism's genome. A genome includes all the coding regions (regions that are translated into molecules of protein) of DNA that form discrete genes, as well as all the noncoding stretches of DNA that are often found in the areas of chromosomes between genes. The sequence, structure, and chemical modifications of DNA not only provide the instructions needed to express the information held within the genome, but also provide the genome with the capability to replicate, repair, package, and otherwise maintain itself. The human genome contains approximately 25,000 genes within its 3,000,000,000 base pairs of DNA, which form the 46 chromosomes found in a human cell. In contrast, Nanoarchaeum equitans, a parasitic prokaryote in the domain Archaea, has one of the smallest known genomes, consisting of 552 genes and 490,885 base pairs of DNA. The study of the structure, function, and inheritance of genomes is called genomics. Genomics is useful for identifying genes, determining gene function, and understanding the evolution of organisms.

According to the head of the European Molecular Biology Laboratory, E. Furlong, the genome encodes the genetic blueprint that coordinates all cellular processes, which ultimately give rise to phenotype. The expression of genetic information is tightly regulated in both time and space at multiple steps, including transcriptional, post-transcriptional and post-translational. The Genome Biology Unit takes a systems biology approach to unravel these complex processes at all scales, integrating wet-lab and computational approaches.

In eukaryotes, many steps of gene expression, such as transcription and RNA processing, take place in the structurally complex environment of the nucleus and often involve remodelling of chromatin into active and inactive states. Messenger RNAs, once exported from the nucleus, undergo additional regulatory steps.

Their translation results in the production of proteins, whose functions define the characteristics of different cell types, or cellular phenotypes. Not all RNAs are translated, however. In recent years, multiple types of non-coding RNAs have been discovered that display diverse functionality. Genetic variation in non-coding and protein-coding genes alike, as well as the regulatory elements that govern their expression, can adversely affect the function of these genes, leading to diseases such as cancer. Groups within the Unit are investigating various aspects of genome biology in order to understand these processes leading from genotype to phenotype.

A notable strength of the Unit is its ability to address questions at different scales, ranging from detailed mechanistic studies (using biochemistry, genetics, microfluidics and chemistry) to genome-wide studies (using functional genomic, proteomic and computational approaches), often by developing new enabling technologies. For example, the development and integration of chemistry and microfluidic devices with the recent advances in next-generation sequencing will facilitate major advances in these areas in the coming years. Global, dynamic and quantitative measurements of biological molecules at all levels (DNA, RNA, proteins, cells, organisms, etc) as well as the integration of hypothesis and discovery-driven research characterise the Unit. The synergy between computational and wet-lab groups provides a very interactive and collaborative environment to yield unprecedented insights into how genetic information is ‘read’ and mediates phenotype through molecular networks.

Here are two definitions provided by a source that I am sure you are all anxious to cite, Google (searched 'genome definition'):

1) the haploid set of chromosomes in a gamete or microorganism, or in each cell of a multicellular organism.

2) the complete set of genes or genetic material present in a cell or organism.

My thoughts:

1) This indicates that we can microscopically see the genome in each cell (as paired chromosomes) upon making a chromosome spread and staining, and even localize individual genes/sequencing using tools such as FISH

2) Genomic sequencing is not conventionally done in a single cell manner, meaning that we receive a composite answer (90% or better being 'correct' depending upon technical issues such as resolving repetitive regions) for the sequence of the genome from the sample, and we may miss what may be important variations present between individual cells not only in cells in the sample but within the rest of the organism

I just feel that it is important to emphasize that the genome we each started with at conception is not exactly the one present currently within each and every cell of our bodies, even if it might appear similar/the same when sequencing a biopsy. I think that the emphasis on "in each cell within a multicellular organism" is important, as we can conceptually understand that while two haploid genomes come together during fertilization, and for the most part genetic material is faithfully copied, it is also the case that within each cell the genome is likely to evolve/mutate over years/decades, meaning that there can be something of a family tree present for genomic lineages present within an organism.

Here is an interesting post by the NIMH director on this topic:

http://www.nimh.nih.gov/about/director/2013/one-person-many-genomes.shtml

with accompanying references... Enjoy!

@ Dacquin Kasumba thank you Dacquin for reference

"haploid set of chromosomes of any species" ......that is referred as genome

Genome refers to the totality of genetic information possessed by an organism. The genome database organized in six major organism groups: eukaryotes, bacteria, archaea, viruses, viroids and plasmids.

Three domains of life; all living things grouped into three domains: eukaryotes, prokaryotes and archaea

The genome structure of prokaryotic and eukaryotic cells are remarkably different, and further variations found among species within each group. The size of eukaryotic genomes is vastly larger than those of prokaryotes. This is partly due to the complexity of eukaryotic organism compared to prokaryotes. However, the size of a particular eukaryotic genome is not directly correlated to the organism complexity because of the presence of a large amount of non-coding DNA.Viruses, although their status as living organisms is doubtful, contain units of genetic information that often also referred to as genomes.

Genomic DNA contains both coding and noncoding sequences. Coding DNA sequences give rise to all of the transcribed RNAs of the cell. Non coding sequences contain information that does not lead to the synthesis of an active RNA molecule or protein, the functions of these sequences are only partially understood and they suggested functioning in DNA packing, chromosome structure, and chromatin organization within the nucleus or in control of gene expression. Others sequences may just be present in the genome to serve as an evolutionary buffer able to withstand nucleotide mutation without disrupting the integrity of the organism.

A genome is an organism’s complete set of DNA, including all of its genes. Each genome contains all of the information needed to build and maintain that organism. In humans, a copy of the entire genome—more than 3 billion DNA base pairs—is contained in all cells that have a nucleus.

A genome is an organism’s complete set of DNA, including all of its genes. It refer to a haploid set of chromosomes of any species. Each genome contains all of the information needed to build and maintain that organism.

Human genome = 22 Autosomes chromosomes + 2 sex chromosomes （X and Y）+ one circular mitochondrial chromosome