Page 47 - Genetics_From_Genes_to_Genomes_6th_FULL_Part3

PART III Analysis of Genetic Information
10

chapter

Genome

Annotation

Once the sequence of a genome has been determined, research-
ers need to determine where functional elements such as genes
reside within these billions of base pairs.
© fredex/Shutterstock RF

chapter outline

• 10.1 Finding the Genes in Genomes
• 10.2 Genome Architecture and Evolution
• 10.3 Bioinformatics: Information Technology
and Genomes
DETERMINATION OF THE 3 BILLION BASE PAIR • 10.4 A Comprehensive Example: The Hemoglobin
SEQUENCE of the human genome, although an amazing Genes
achievement, was only the first step of the Human
Genome Project. The nucleotide sequence by itself does
not answer several key questions: Where are the genes?
How many are there? What are their products? What lies in the genome other than
genes? How are the genes and other genomic elements organized along the chromo-
somes? Without these answers, we cannot begin to understand how the human gen-
otype (that is, the sequence) determines the complexity of the human phenotype.
In this chapter, we describe the annotation of the human genome; that is, the
process of parsing out which sequences of DNA do which tasks. The process of
annotation requires the compilation of data from diverse methods of investigation,
including a variety of molecular experiments as well as complex computer algo-
rithms to analyze the vast amount of data obtained. One lesson of this discussion is
that the genomes of species other than humans provide important clues to the anno-
tation of the human genome. We further describe some of the key findings from the
Human Genome Project so that you can picture in a general fashion how these
3 billion nucleotides are organized.
A key feature of this chapter is an introduction to Internet-based resources, par-
ticularly a large database based at the National Center for Biotechnology Informa-
tion (NCBI) at the U.S. National Institutes of Health, that you yourself can use to
explore the human genome and other sequenced genomes. The chapter concludes
with a comprehensive example illustrating how the sequence of the human genome
has helped us to understand the nature of genetic diseases called hemoglobinopa-
thies that disrupt our blood’s ability to carry oxygen.

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