The "human genome" was sequenced by the Human Genome Project around 2000. But I don't understand what was done and what its significance is. Questions:

  1. Wasn't a single person's genome sequenced? I.e. we have the 3.3 billion base pairs for some individual, right? So how does that pertain to me since I undoubtedly have different alleles than that person.
  2. Isn't most of our DNA so-called "junk DNA?" Did the human genome project distinguish the portions that code for proteins from this junk area?
  3. What determines a "gene"? How do we know where one gene begins and ends, especially given that a gene can comprise up to 2 million base pairs?
  4. Suppose I have the 3.3 billion base pairs for some individual. What can I do with that information? Don't I need to know much much more in order to make any use of those data?
  • 1
    $\begingroup$ We welcome new contributors to SE Biology, but expect them to check out what questions are appropriate on this site, even if they have used other SE sites. This section of the help should make it clear that posters are expected to ask specific questions and show evidence of having researched them themselves before posting. Yours is a set of four basic questions, for which you show no evidence of having consulted the obvious source. I have therefore voted to close. $\endgroup$ – David Sep 17 '18 at 10:48

Okay, a quick answer since I don't have time to go into all the details:

1) As correctly mentioned in the comments already the human genome project had multiple DNA donors, however up 70% of the final genome assembly was from a single person. In order to gt a deeper understanding of the genomic variance in the human population we now have the 1000 genomes project.

2) The fact a such a large portion of the human genome is not gene-coding (the term junk-DNA is not really correct/misleading since quite a bit of it does have unknown or regulatory functions) was not really known before the completion of the human genome project - only after we knew the full genome sequence this became obvious.

3) Genes can either be detected experimentally by doing transcriptome sequencing and comparing the recovered RNA sequences to the genome. This tells us which parts of the genome are in fact transcribed (and includes more than just protein coding genes). It's also possible to find genes just by analysing the genome sequence and looking for open reading frames (in exons), transcription start sites and other known elements. However, this method is only good for finding protein coding genes, other genes (i.e. miRNA or lincRNA) will most likely not be found.

4) Yes, the full genome sequence of an individual alone doesn't tell you anything. In order to get interpretable / useful information out of it you need to compare it with other database sources, such as the SNP-database.

  • $\begingroup$ The answer to 1. is wrong: The HGP sequenced a small number of individuals from european descent. Without doing so, they wouldn't have been able to find differences between different allels in the individuals. Celera on the other hand sequenced mostly the DNA of Craig Venter. $\endgroup$ – Chris Sep 17 '18 at 8:22
  • $\begingroup$ @Chris — "The answer to 1…". Quite. The poster has four questions. That is what needs addressing in my opinion. When the answer is a book chapter, people here will provide "quick answers" of limited utility. $\endgroup$ – David Sep 17 '18 at 10:51
  • $\begingroup$ @Chris Yep, I didn't check the sources there properly. I edit my answer. $\endgroup$ – Nicolai Sep 17 '18 at 12:23

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