This has been confirmed also in D. Overall, it seems that the GC composition of highly and poorly expressed genes in specific tissues affects the mRNA GC content to a small extent and a global compensation between them may exist. Recent works conducted on DS subjects showed typical alterations of the metabolome and whole transcriptome [ 46 , 47 ]. Chromosome 21 GC content is one of the closest to the mean genomic GC content, thus the presence of a third copy of chromosome 21 would not cause a great change in GC composition at genomic level.
For example, a recent work showed a high expression of high-GC-content mRNAs in psoriasis lesion transcriptome, while resolving lesions had a low expression of these mRNAs [ 49 ].
More in-depth analysis will be needed to validate the use of these indexes as indicators in the comparison of disease versus normal conditions. Genomic, mRNA and transcriptomic GC content determination can be useful in DNA and RNA sequencing analyses where GC content bias for the Illumina sequencing technology has been documented as likely introduced at the library preparation step, resulting in confounding DNA copy number studies and expression fold-change estimates [ 50 ].
In conclusion, we provide an update on fundamental human genome parameters and a first characterisation of the mRNA and transcriptome GC contents. Our results may represent a solid basis for further investigations on human structural and functional genomics [ 29 , 51 ] while also providing a framework for the comparative analysis of other genomes.
Determination of the length, weight and relative GC content of genome is subjected to the accuracy of the genome assembly and to the variability existing among individuals [ 41 ]. Regarding mtDNA, although its sequence has been exactly determined, the mtDNA molecule copy number per cell is of difficult estimation [ 52 ].
Regarding GC content at mRNA and transcriptomic levels, the analysis is limited to genes for which an expression value together with the corresponding longest mRNA nucleotide sequence is publicly available.
Strachan T, Read A. Human Molecular Genetics. Garland science. Google Scholar. Sequence and organization of the human mitochondrial genome. Initial sequencing and analysis of the human genome. The sequence of the human genome. Evaluation of GRCh38 and de novo haploid genome assemblies demonstrates the enduring quality of the reference assembly. Genome Res. Improvements and impacts of GRCh38 human reference on high throughput sequencing data analysis. Molecular biology of the cell. New York: Garland Science; Ross DW.
The human genome: information content and structure. Hosp Pract Histones and histone modifications. Curr Biol. Venter C, Cohen D. The century of biology. New Perspect Q. Article Google Scholar. Ram M. Fundamentals of cytogenetics and genetics. Clayton J, Dennis C. UK: Palgrave Macmillan; Divan A, Royds J. Molecular biology: a very short introduction. Oxford: Oxford University Press; Book Google Scholar. Determination of the base composition of deoxyribonucleic acid from its buoyant density in CsCl.
J Mol Biol. Evolutionary genomics in Metazoa: the mitochondrial DNA as a model system. Microbiol Res. Genome size and metabolic intensity in tetrapods: a tale of two lines.
Proc Biol Sci. The bat genome: GC-biased small chromosomes associated with reduction in genome size. Both selective and neutral processes drive GC content evolution in the human genome. BMC Evol Biol. Compositional pressure and translational selection determine codon usage in the extremely GC-poor unicellular eukaryote Entamoeba histolytica. A simple model based on mutation and selection explains trends in codon and amino-acid usage and GC composition within and across genomes. Genome Biol.
GC skew is a conserved property of unmethylated CpG island promoters across vertebrates. Nucleic Acids Res. Composition-sensitive analysis of the human genome for regulatory signals. Silico Biol. The next galaxy? The end of the Universe? Let's start out with people. Each human cell has around 6 feet of DNA. Let's say each human has around 10 trillion cells this is actually a low ball estimate.
This would mean that each person has around 60 trillion feet or around 10 billion miles of DNA inside of them. The Earth is about 93 million miles away from the sun.
So your DNA could stretch to the sun and back 61 times. When we multiply 10 billion miles of DNA by 6. Something like 6. DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Mitochondria are structures within cells that convert the energy from food into a form that cells can use. Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people.
The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.
Each base is also attached to a sugar molecule and a phosphate molecule. They have their own set of genes because they are thought to have evolved from bacteria that were engulfed by eukaryotic cells cells containing a nucleus some 1. That's how many feet long the DNA from one of your cells would be if you uncoiled each strand and placed them end to end. Do this for all your DNA, and the resulting strand would be 67 billion miles long—the same as about , round trips to the Moon.
That's the length in inches across a cell's nucleus, which holds your DNA. If you sliced human hair into tenths lengthwise, each slice would be about that big around. To keep the space tidy, DNA spools around a group of proteins called histones.
The resulting taut package of wound-up DNA is called chromatin, which winds up even tighter to form your chromosomes. The DNA of any two people on Earth is But 0. Our environment also contributes to our individuality. That's the fraction of human genes estimated to be regulated by microRNAs. These genetic "micromanagers" consist of only about 22 RNA units called nucleotides, but they can stop a gene from producing the protein it encodes.
Scientists have identified hundreds of microRNAs in people and have linked disruptions in some of them to certain cancers.
0コメント