Human Genome Sequencing Completed

Arthur Dent '99 writes "According to this article at Reuters, the last chromosome in the human genome has finally been sequenced, taking 150 British and American scientists 10 years to complete. The sequenced chromosome, Chromosome 1, is the largest chromosome, with nearly twice as many genes as the average chromosome, making up eight percent of the human genetic code. The Human Genome Project has published the sequence online in the journal Nature, according to the article. It contains 3,141 genes (over 1,000 of them newly discovered), and 4,500 new SNPs -- single nucleotide polymorphisms -- which are the variations in human DNA that make people unique."

Comments

Re:A simple question

[FTL]

> Why do one chromosone have more genes than others?

Same reason some source code files contain more lines of code than others. They do different things.

SNPs

[Michael Woodhams]

From the fine article:
"The scientists also identified 4,500 new SNPs -- single nucleotide polymorphisms -- which are the variations in human DNA that make people unique."

There are other variations which make us unique.
Alternate alleles*
Indels (insertions/deletions)
Variable numbers of repeats.*

The genetic code uses 4 letters, but I'll use English for explaination.
A SNP is a single letter which has different values in different individuals: "The cat and the dog" vs "the hat and the dog".
An indel is where letters have been inserted into one sequence or deleted from another (without additional data, we can't distinguish these possibilities.)
"The cat and the dog" vs "the cat and the big dog".
In alternate alleles there are a bunch of changes which always stick together, e.g. we observe "the cat and the big dog" and "the cat and the small mouse", but never (or exceedingly rarely) "the cat and the big mouse" or "the cat and the small dog."
Variable repeats are a special case of indels, but common enough to warrant a category of their own. "The cat and and and the dog" vs "the cat and and and and and the dog".