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.

What is a gene?

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!!

Back to chromosomes and genes

A genome is made up of all of the DNA in an organism’s chromosomes—it is all of its genetic information.

Genome

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.

Genome=library

So, the library contains over six billion letters total;

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.

The Human Genome Project 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.

The Human Genome Project Why bother? Just a few reasons….

Improved disease diagnosis Determining genetic predisposition to

disease Developing gene therapy Designing custom drugs