Final answer:
The sequencing of the first human genome utilized chromosome walking by the Human Genome Project and shotgun sequencing by the Celera group, with the latter proving to be faster. Pairwise-end sequencing, an advancement of shotgun sequencing, was particularly useful in sequencing complex genomes such as the human genome. This led to the complete sequence being published in 2003.
Step-by-step explanation:
Sequencing the First Human Genome
The first human genome was sequenced through the efforts of an international research group called the Human Genome Project (HGP). They used an approach that involved sequencing individual genes and aligning them along the genome, also known as chromosome walking. On the other hand, the Celera group led by Craig Venter employed a different approach, known as shotgun sequencing, which was faster than the HGP's method.
Chromosome Walking vs. Shotgun Sequencing
Chromosome walking involves sequencing short, adjacent pieces of a genome in a linear fashion. It is a methodical process that incrementally moves across the chromosome, from one cloned DNA fragment to the next overlapping fragment. In contrast, in shotgun sequencing, the DNA is randomly cut into numerous small pieces, which are sequenced individually.
The sequences are then assembled using computer algorithms that identify overlaps between the fragments, creating a continuous sequence known as a contig. The pairwise-end sequencing, an advanced form of shotgun sequencing, was developed to sequence complex genomes like that of humans, where both ends of the fragments are sequenced to aid in the reconstruction of the DNA sequence.
In 2003, with the advancement of these techniques, the first complete human genome sequence was published. The efforts of sequencing the human genome have brought along various ethical discussions, including concerns about genetic discrimination.