Genes and genomes

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Transcript Genes and genomes

A gene is a particular sequence (a string) of
nucleotides on a particular site of a
chromosome. It is made up of combinations
of A, T, C, and G. These unique combinations
code for a particular amino acid, much as
letters join together to form words.
A chromosome is nature’s great packaging
experiment – it contains tightly coiled DNA
around special proteins. The DNA of a human
being’s 23 chromosomes, when uncoiled, is 2
meters long!!
A genome is made up of all of the DNA in an
organism’s chromosomes—it is all of its genetic
An analogy to the human genome stored on
DNA is that of instructions stored in a library.
The library would contain
46 books (chromosomes).
The books range in size from 400 to 3340
pages (genes), which is 48 to 250 million
letters (A,C,G,T) per book.
So, the library contains over six billion letters
The library fits into a cell nucleus the size of
a pinpoint;
A copy of the library (all 46 books) is
contained in almost every cell of our body.
A 13-year project (1990-2003) that
discovered all estimated 20,000 to 25,000
human genes.
The project also discovered the complete
sequence of all 3 billion DNA bases (A,T,C,G).
All the information in
stored in databases.
Why bother? Just a few reasons….
Improved disease diagnosis
Determining genetic predisposition to disease
Developing gene therapy
Designing custom drugs