GENOME
A
genome is all the DNA in an organism, packaged in
46 pieces (for the human genome) including all its
genes. These 46 pieces of chromosomes consist of some
3 billion base pairs or bp arranged in a particular
order. There are approximately 30,000 genes in the
human genome.
The
four chemical bases are very much like the letters
of the English language in which a word is made up
of a specific arrangement of the 26 letters. Just
like the English language, the genome is made up of
the four letters A, T, C, G but this word is 3 billion
letters long! It goes something like this ATGCCTGCAGTC
…. 3 billion of it.
The
specific arrangement of the 4 "letters"
A, T, G and C is extremely important. The order underlies
all of life's diversity, even dictating whether an
organism is human or another species such as yeast,
rice, or fruit fly. Only specific stretches of the
genome are genes. If you took some letters and jumbled
them together, most of the resulting sequence would
be rubbish. Similarly, only specific stretches of
the genome are genes - as much as 97 per cent of it
is junk - with no known purpose.
