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Explore the wide distribution of gene sizes and the implications of polymorphisms at different levels in genomes. Discover the importance of RFLPs and SNPs for genetic mapping, personalized medicine, and linking genealogy. Learn how genetics influence human health and performance in exercise science. Understand the significance of genome size and genetic complexity, and the role of nonrepetitive and repetitive DNA sequences. Delve into the conservation of exons for gene coding and the unique characteristics of organelle genomes. Get insights from the Human Genome Project's findings on gene diversity and similarities across species.
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Ex Biochem c4-genome 3.6 Genes Show a Wide Distribution of Sizes • Most genes are uninterrupted in yeasts, but are interrupted in higher eukaryotes. Figure 3.10
Ex Biochem c4-genome 4.3 Individual Genomes Show Extensive Variation • Polymorphism多型性 may be detected: • at phenotypic level when a sequence affects gene function (phenotype 表現型) • at the restriction fragment level when it affects a restriction enzyme target site • at the sequence level by direct analysis of DNA (genotype 基因型) • The alleles of a gene show extensive polymorphism at the sequence level • Many sequence changes do not affect function.
Ex Biochem c4-genome Figure 4.1
Ex Biochem c4-genome 4.4 RFLPs and SNPs Can Be Used for Genetic Mapping • RFLP: Restriction fragment length polymorphism
Ex Biochem c4-genome Figure 4.3
Ex Biochem c4-genome Single nucleotide polymorphism (SNP)單核甘酸多型性 • can affect how humans develop diseases, respond to pathogens, chemicals, drugs, vaccines... • Personalized medicine • comparing regions of the genome between cohorts
Ex Biochem c4-genome RFLPs and SNPs • RFLPs and SNPs: • can be the basis for linkage maps • are useful for establishing parent–progeny relationships
Ex Biochem c4-genome Application to exercise science • Identification of performance-related genes • Identification of performance-related genotypes • Talent scouting at molecular level • Practical application?
Ex Biochem c4-genome Genes may affect performance, fitness Rankinen T, MSSE, 2006
Ex Biochem c4-genome Bray MS, MSSE, 2009
Ex Biochem c4-genome 4.5 Why Are Genomes So Large? • There is no good correlation between genome size and genetic complexity. Figure 4.5
Ex Biochem c4-genome 4.5 Why Are Genomes So Large? • increase in the minimum genome size required to make organisms of increasing complexity. • wide variations in the genome sizes of organisms within many phyla. Figure 4.6
Ex Biochem c4-genome 4.6 Eukaryotic Genomes Contain Nonrepetitive & Repetitive DNA Sequence • The kinetics of DNA reassociation after a genome has been denatured distinguish sequences by their frequency of repetition in the genome. • Genes are generally coded by sequences in nonrepetitive DNA.
Ex Biochem c4-genome • Larger genomes within a phylum do not contain more genes. • They do have large amounts of repetitive DNA. • A large part of repetitive DNA may be made up of transposons. Figure 4.8
Ex Biochem c4-genome 4.7 Genes Can Be Isolated by the Conservation of Exons • Conservation of exons can be used as the basis for identifying coding regions: • By identifying fragments whose sequences are present in multiple organisms Figure 4.10
Ex Biochem c4-genome 4.9 Organelles Have DNA • Mitochondria and chloroplasts have genomes that show non-Mendelian inheritance. • Typically they are maternally inherited. Figure 4.15
Ex Biochem c4-genome • Organelle genomes may undergo somatic segregation in plants. • Comparisons of mitochondrial DNA suggest that humans are descended from a single female who lived 200,000 years ago in Africa. Figure 4.14
Ex Biochem c4-genome 4.10 Organelle Genomes Are Circular DNAs That Code for Organelle Proteins • Organelle genomes are usually (but not always) circular molecules of DNA. • Organelle genomes code for some, but not all, of the proteins found in the organelle. Figure 4.16
Ex Biochem c4-genome 4.11 Mitochondrial DNA Organization Is Variable • Animal cell mitochondrial DNA is extremely compact and typically codes for: • 13 proteins • 2 rRNAs • 22 tRNAs Figure 4.17
Ex Biochem c4-genome 4.13 Mitochondria Evolved by Endosymbiosis Figure 4.20
Ex Biochem c4-genome Results from Human Genome Project人類基因體計畫 • The human genome contains 3164.7 million chemical nucleotide bases (A, C, T, and G). • The average gene consists of 3000 bases, but sizes vary greatly, with the largest known human gene being dystrophin at 2.4 million bases. • The total number of genes is estimated at 30,000 • much lower than previous estimates of 80,000 to 140,000 • Almost all (99.9%) nucleotide bases are exactly the same in all people. • The functions are unknown for over 50% of discovered genes.
Ex Biochem c4-genome Results from Human Genome Project • Humans share most of the same protein families with worms, flies, and plants • but the number of gene family members has expanded in humans, especially in proteins involved in development and immunity • about 1.4 million locations where single-base DNA differences (SNPs) occur in humans