From The Free On-line Dictionary of Computing (19 January 2023):
gigabyte
gig
<unit, data> (GB or colloquially "gig") A unit of data equal to
one billion bytes but see binary prefix for other definitions.
A gigabyte is 1000^3 bytes or 1000 megabytes.
A human gene sequence (including all the redundant codons)
contains about 1.5 gigabytes of data.
1000 gigabytes are one terabyte.
See prefix.
(http://bitesizebio.com/articles/how-much-information-is-stored-in-the-human-genome/).
(2013-11-03)