17.1 Genomes can be mapped both genetically and physically.
Genome Maps
• Genetic maps show the relative location of genes on a chromosome as determined by recombination frequencies. Genetic maps measure distance in centimorgans. (p. 344)
• Physical maps show relative positions of landmarks within specific DNA sequences and measure distance in base-pairs. (p. 344)
17.2 Genome sequencing produces the ultimate physical map.
Sequencing
• Large-scale genome sequencing relies on an automated sequencer and computer analysis, but to reduce errors, genomes are cut into short segments for replication. (p. 346)
• Clone-by-clone sequencing starts by constructing a physical map with many landmarks and then sequencing known sites. (p. 347)
• Shotgun cloning sequences cloned fragments, and then uses computational analysis to determine the whole sequence from the overlapping sequences. (p. 347)
17.3 Being more complex does not necessarily require more genes.
Human Genome Project
• The Human Genome Project originated in 1990, and success was announced in 2001. (p. 348)
• Eukaryotic genomes appear to be larger than prokaryotic genomes, but the size of the organism does not appear to play a determining role. (p. 348)
Genome Geography
• Bioinformatic approaches can be used to identify gene sequences. (p. 349)
• Alternative splicing yields different proteins that can have different functions. (p. 349)
• Four different classes of protein-encoding genes found in eukaryotic genomes are (1) single-copy genes, (2) segmental duplications, (3) multigene families, and (4) tandem clusters. (p. 349)
• Only about 1% of the human genome is devoted to protein-encoding genes. (p. 350)
• Six major sorts of noncoding human DNA are (1) noncoding DNA within genes, (2) structural DNA, (3) simple sequence repeats, (4) segmental duplications, (5) pseudogenes, and (6) transposable elements. (p. 350)
Comparative Genomics
• Synteny refers to the conserved arrangements of segments of DNA in related genomes. (p. 352)
• Comparisons with the sequenced syntenous segment in another species can help in determining evolutionary relationships. (p. 352)
17.4 Genomics is opening a new window on life.
Functional Genomics
• Genomics is shifting toward functional genomics, the study of the function of genes and their products. (p. 354)
• DNA microarrays can screen large numbers of genes very rapidly. (p. 355)
Proteomics
• Proteins are much more difficult to study than DNA because of the posttranslational modification and formation of protein complexes. (p. 356)
• Proteonomics is an effort to identify and study proteins coded for by the genome, and is distinguished from traditional protein biochemistry by the use of new methods to quickly identify and characterize large numbers of proteins. (p. 356)
Using Genomic Information
• The potential of genomics to improve human health through medical diagnostics and to improve nutrition through agriculture is enormous. (p. 357)
• Genomic science is also a source of ethical challenges and dilemmas, such as patient rights and personal privacy issues. (p. 358)