How long is a dna molecule in humans

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. As it turns out, some of this "junk DNA" has other jobs. So far, scientists have learned that it can help organize the DNA within the nucleus and help turn on or off the genes that do code for proteins.

That's the number of chromosomes in the nuclei of a person with Down syndrome and certain other genetic conditions. Most human cells have 46 chromosomes, but occasionally, a glitch in cell division results in a cell with too few or too many chromosomes. When this happens in egg or sperm cells, the child can have an abnormal number of chromosomes. People with Down syndrome have an extra copy of chromosome 21, one of the smallest chromosomes in the genome.

That's the year when scientists uncovered the double-helical structure of DNA. Until then, scientists knew that traits were passed down to offspring in predictable ways, but they didn't understand how.

All that changed when James Watson and Francis Crick showed that DNA is shaped like a spiral staircase that can be split, copied and passed on to future generations. Watson and Crick received a Nobel Prize in for their discovery.

Toggle navigation Toggle Search. It looks like your browser does not have JavaScript enabled. Please turn on JavaScript and try again. Highlight Header. This translates to around.

So all the bacteria in the world have about 3. How far is 3. Well, it is about billion light years of DNA. The end of the observable Universe is about 14 billion light years away. So if we stretched out bacterial DNA it would go to the end of the Universe and back around 23 times.

Of course it would be incredibly thin and so actually doesn't take up much space in the Universe. So that's just human and bacterial DNA. Well, mostly bacterial since human is so piddly in comparison. I haven't added all of the rest of the DNA out there.

I'll leave that to you. Search-Icon Created with Sketch. KQED is a proud member of. Always free. The sum of these values related to each transcriptome map gives the transcriptomic GC content Table 3.

In this work we have determined, to the best of our knowledge, basic parameters describing the normal human reference genome: the length, expressed in terms of both bp and unit of length cm, m , weight in unit of mass, pg and relative GC content expressed in percentages, for the whole human nuclear genome, for each chromosome and for mtDNA. We have based our calculations on the GRCh38 assembly, which is longer and more contiguous than previous reference assembly versions and provides a sequence-based representation for genomic features such as centromeres and telomeres for the first time [ 5 ], which, although variable among cell types and ages, would affect our estimates to a small extent.

However, the human genetic diversity ranges from the single-nucleotide variation to large chromosomal events [ 41 , 42 ]. Our results are not far from previous rough estimates Table 1 , however the more accurate determination of the human genome length and weight might offer interesting possibilities. Applying our analysis to other genomes would be useful to update these indexes.

Another interesting possibility offered by the knowledge of human nuclear genome length is the derivation of the total human DNA volume, in order to estimate the efficiency of DNA in data storage, resulted to be in the order of 10 4 fold superior in comparison to the most currently advanced hard disks Additional file 7 : Discussion.

The genome weight is a parameter useful for the correlation with the DNA extraction yields through different methods [ 45 ]. Regarding GC content analysis at genomic level, our results are in agreement with a recent study [ 6 ].

Through the implementation of TGCA software we have also determined the GC content at mRNA and transcriptomic levels for the first time, a novel concept we propose here, which is the GC percentage calculated in the mRNA amount actually expressed in a tissue. 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.

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